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Configuring vPCs
This chapter describes how to configure virtual port channels (vPCs) on Cisco NX-OS devices.
You can use any of the interfaces of the Nexus 9000 device for the vPC peer link.
The port channel compatibility parameters must be the same for all the port channel members on the physical
switch.
You cannot configure shared interfaces to be part of a vPC.
Note
The port channel compatibility parameters must also be the same for all vPC member ports on both peers
and therefore you must use the same type of module in each chassis.
• Information About vPCs, page 1
• Licensing Requirements for vPCs, page 34
• Guidelines and Limitations, page 34
• Default Settings, page 36
• Configuring vPCs, page 36
• Verifying the vPC Configuration, page 64
• Monitoring vPCs, page 65
• Configuration Examples for vPCs, page 65
• Related Documents, page 67
Information About vPCs
vPC Overview
A virtual port channel (vPC) allows links that are physically connected to two different Cisco Nexus 9000
Series devices to appear as a single port channel by a third device (see figure). The third device can be a
switch, server, or any other networking device that supports port channels. A vPC can provide Layer 2
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multipathing, which allows you to create redundancy and increase the bisectional bandwidth by enabling
multiple parallel paths between nodes and allowing load balancing traffic.
Figure 1: vPC Architecture
You can use only Layer 2 port channels in the vPC. A vPC domain is associated to a single Virtual Device
Context (VDC), so all vPC interfaces belonging to a given vPC domain must be defined in the same VDC.
You configure the port channels by using one of the following:
• No protocol
• Link Aggregation Control Protocol (LACP)
When you configure the port channels in a vPC—including the vPC peer link channel—without using LACP,
each device can have up to eight active links in a single port channel. When you configure the port channels
in a vPC—including the vPC peer link channels—using LACP, each device can have eight active links and
eight standby links in a single port channel. (See the “vPC Interactions with Other Features” section for more
information on using LACP and vPCs.)
Note
You must enable the vPC feature before you can configure or run the vPC functionality.
The system automatically takes a checkpoint prior to disabling the feature, and you can roll back to this
checkpoint.
After you enable the vPC functionality, you create the peer-keepalive link, which sends heartbeat messages
between the two vPC peer devices.
You can create a vPC peer link by configuring a port channel on one Cisco Nexus 9000 Series chassis by
using two or more 10-Gigabit Ethernet ports or 40-Gigabit Ethernet ports. To ensure that you have the correct
hardware to enable and run a vPC, enter the show hardware feature-capability command. If you see an X
across from the vPC in your command output, your hardware cannot enable the vPC feature.
We recommend that you configure the vPC peer link Layer 2 port channels as trunks. On another Cisco Nexus
9000 Series chassis, you configure another port channel again using two or more 10-Gigabit Ethernet ports
or 40-Gigabit Ethernet ports in the dedicated port mode. Connecting these two port channels creates a vPC
peer link in which the two linked Cisco Nexus devices appear as one device to a third device. The third device,
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or downstream device, can be a switch, server, or any other networking device that uses a regular port channel
to connect to the vPC. If you are not using the correct module, the system displays an error message.
We recommend that you configure the vPC peer links on dedicated ports of different modules to reduce the
possibility of a failure. For the best resiliency scenario, use at least two modules.
If you must configure all the vPC peer links and core-facing interfaces on a single module, you should configure
a track object that is associated with the Layer 3 link to the core and on all the links on the vPC peer link on
both vPC peer devices. Once you configure this feature and if the primary vPC peer device fails, the system
automatically suspends all the vPC links on the primary vPC peer device. This action forces all the vPC traffic
to the secondary vPC peer device until the system stabilizes.
You can create a track object and apply that object to all links on the primary vPC peer device that connect
to the core and to the vPC peer link. See the Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration
Guide for information about the track interface command.
The vPC domain includes both vPC peer devices, the vPC peer-keepalive link, the vPC peer link, and all of
the port channels in the vPC domain connected to the downstream device. You can have only one vPC domain
ID on each device.
In this version, you can connect each downstream device to a single vPC domain ID using a single port channel.
Note
Always attach all vPC devices using port channels to both vPC peer devices.
A vPC (see figure) provides the following benefits:
• Allows a single device to use a port channel across two upstream devices
• Eliminates Spanning Tree Protocol (STP) blocked ports
• Provides a loop-free topology
• Uses all available uplink bandwidth
• Provides fast convergence if either the link or a device fails
• Provides link-level resiliency
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• Assures high availability
Figure 2: vPC Interfaces in One VDC
vPC Terminology
The terminology used in vPCs is as follows:
• vPC—The combined port channel between the vPC peer devices and the downstream device.
• vPC peer device—One of a pair of devices that are connected with the special port channel known as
the vPC peer link.
• vPC peer link—The link used to synchronize states between the vPC peer devices. Both ends must be
on 10-Gigabit Ethernet or 40-Gigabit Ethernet interfaces.
• vPC member port—An interface that belongs to a vPC.
• Host vPC port—A Fabric Extender host interfaces that belongs to a vPC.
• vPC domain—This domain includes both vPC peer devices, the vPC peer-keepalive link, and all of the
port channels in the vPC connected to the downstream devices. It is also associated to the configuration
mode that you must use to assign vPC global parameters.
• vPC peer-keepalive link—The peer-keepalive link monitors the vitality of a vPC peer Cisco Nexus 9000
Series device. The peer-keepalive link sends configurable, periodic keepalive messages between vPC
peer devices.
We recommend that you associate a peer-keepalive link to a separate virtual routing and forwarding
(VRF) instance that is mapped to a Layer 3 interface in each vPC peer device. If you do not configure
a separate VRF, the system uses the management VRF by default. However, if you use the management
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interfaces for the peer-keepalive link, you must put a management switch connected to both the active
and standby management ports on each vPC peer device (see figure).
Figure 3: Separate Switch Required to Connect Management Ports for vPC Peer-Keepalive Link
No data or synchronization traffic moves over the vPC peer-keepalive link; the only traffic on this link
is a message that indicates that the originating switch is operating and running a vPC.
• vPC member port—Interfaces that belong to the vPCs.
• Dual-active— Both vPC peers act as primary. This situation occurs when the peer-keepalive and peer-link
go down when both the peers are still active. In this case, the secondary vPC assumes that the primary
vPC is inactive and acts as the primary vPC.
• Recovery—When the peer-keepalive and the peer-link come up, one switch becomes the secondary
vPC. On the switch that becomes the secondary vPC, the vPC links go down and come back up.
vPC Peer Link Overview
You can have only two devices as vPC peers; each device can serve as a vPC peer to only one other vPC peer.
The vPC peer devices can also have non-vPC links to other devices.
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See the following figure for invalid vPC peer configurations.
Figure 4: vPC Peer Configurations That Are Not Allowed
To make a valid configuration, you first configure a port channel on each device and then configure the vPC
domain. You assign the port channel on each device as a peer link, using the same vPC domain ID. For
redundancy, we recommend that you should configure at least two of the dedicated ports into the port channel
because if one of the interfaces in the vPC peer link fails, the device automatically falls back to use another
interface in the peer link.
Note
We recommend that you configure the Layer 2 port channels in trunk mode.
Many operational parameters and configuration parameters must be the same in each device connected by a
vPC peer link (see the “Compatibility Parameters for vPC Interfaces” section). Because each device is completely
independent on the management plane, you must ensure that the devices are compatible on the critical
parameters. vPC peer devices have separate control planes. After configuring the vPC peer link, you should
display the configuration on each vPC peer device to ensure that the configurations are compatible.
Note
You must ensure that the two devices connected by the vPC peer link have certain identical operational
and configuration parameters. For more information on required configuration consistency, see the
“Compatibility Parameters for vPC Interfaces” section.
When you configure the vPC peer link, the vPC peer devices negotiate that one of the connected devices is
the primary device and the other connected device is the secondary device (see the “Configuring vPCs” section).
The Cisco NX-OS software uses the lowest MAC address to elect the primary device. The software takes
different actions on each device—that is, the primary and secondary—only in certain failover conditions. If
the primary device fails, the secondary device becomes the new primary device when the system recovers,
and the previously primary device is now the secondary device.
You can also configure which of the vPC devices is the primary device. Changing the priority of the vPC peer
devices can cause the interfaces in your network to go up and down. If you want to configure the role priority
again to make one vPC device the primary device, configure the role priority on both the primary vPC device
with a lower priority value and the secondary vPC device with the higher value. Then, shut down the port
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channel that is the vPC peer link on both devices by entering the shutdown command, and finally reenable
the port channel on both devices by entering the no shutdown command.
Note
We recommend that you use two different modules for redundancy on each vPC peer device on each vPC
peer link.
The software keeps all traffic that forwards across the vPC peer devices as local traffic. A packet that ingresses
the port channel uses one of the local links rather than moving across the vPC peer link. Unknown unicast,
multicast, and broadcast traffic (including STP BPDUs) are flooded across the vPC peer link. The software
keeps the multicast forwarding state synchronized on both of the vPC peer devices.
You can configure any of the standard load-balancing schemes on both the vPC peer link devices and the
downstream device (see the “Configuring Port Channels” chapter for information about load balancing).
Configuration information flows across the vPC peer links using the Cisco Fabric Services over Ethernet
(CFSoE) protocol. (See the “vPC and Orphan Ports” section for more information about CFSoE.)
All MAC addresses for those VLANs configured on both devices are synchronized between vPC peer devices.
The software uses CFSoE for this synchronization. (See the “vPC and Orphan Ports” section for information
about CFSoE.)
If the vPC peer link fails, the software checks the status of the remote vPC peer device using the peer-keepalive
link, which is a link between vPC peer devices that ensures that both devices are up. If the vPC peer device
is up, the secondary vPC device disables all vPC ports on its device, to prevent loops and disappearing or
flooding traffic. The data then forwards down the remaining active links of the port channel.
Note
We recommend that you create and configure a separate VRF and configure a Layer 3 port on each vPC
peer device in that VRF for the vPC peer-keepalive link. The default ports and VRF for the peer-keepalive
are the management ports and VRF.
The software learns of a vPC peer device failure when the keepalive messages are not returned over the
peer-keepalive link.
Use a separate link (vPC peer-keepalive link) to send configurable keepalive messages between the vPC peer
devices. The keepalive messages on the vPC peer-keepalive link determines whether a failure is on the vPC
peer link only or on the vPC peer device. The keepalive messages are used only when all the links in the peer
link fail. See the “Peer-Keepalive Link and Messages” section for information about the keepalive message.
Features That You Must Manually Configure on the Primary and Secondary Devices
You must manually configure the following features to conform to the primary/secondary mapping of each
of the vPC peer devices:
• STP root—Configure the primary vPC peer device as the STP primary root device and configure the
vPC secondary device to be the STP secondary root device. See the “vPC Peer Links and STP” section
for more information about vPCs and STP.
◦We recommend that you configure the vPC peer link interfaces as STP network ports so that Bridge
Assurance is enabled on all vPC peer links
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◦We recommend that you configure Rapid per VLAN Spanning Tree plus (PVST+) so that the
primary device is the root for all VLANs and configure Multiple Spanning Tree (MST) so that the
primary device is the root for all instances.
• Layer 3 VLAN network interface—Configure Layer 3 connectivity from each vPC peer device by
configuring a VLAN network interface for the same VLAN from both devices.
• HSRP active—If you want to use Hot Standby Router Protocol (HSRP) and VLAN interfaces on the
vPC peer devices, configure the primary vPC peer device with the HSRP active highest priority. Configure
the secondary device to be the HSRP standby and ensure that you have VLAN interfaces on each vPC
device that are in the same administrative and operational mode. (See the “vPC Peer Links and Routing”
section for more information on vPC and HSRP.)
We recommend that you configure Unidirectional Link Detection (UDLD) on both sides of the vPC peer link.
See the “Configuring the UDLD Mode” section for information about configuring UDLD.
Configuring Layer 3 Backup Routes on a vPC Peer Link
You can use VLAN network interfaces on the vPC peer devices to link to Layer 3 of the network for such
applications as HSRP and PIM. However, we recommend that you configure a separate Layer 3 link for
routing from the vPC peer devices, rather than using a VLAN network interface for this purpose.
Ensure that you have a VLAN network interface configured on each peer device and that the interface is
connected to the same VLAN on each device. Also, each VLAN interface must be in the same administrative
and operational mode. For more information about configuring VLAN network interfaces, see the “Configuring
Layer 3 Interfaces” chapter.
If a failover occurs on the vPC peer link, the VLAN interfaces on the vPC peer devices are also affected. If
a vPC peer link fails, the system brings down associated VLAN interfaces on the secondary vPC peer device.
You can ensure that specified VLAN interfaces do not go down on the vPC secondary device when the vPC
peer link fails.
Use the dual-active exclude interface-vlan command to configure this feature.
Note
When you attach a Layer 3 device to a vPC domain, the peering of routing protocols using a VLAN also
carried on the vPC peer link is not supported. If routing protocol adjacencies are needed between vPC
peer devices and a generic Layer 3 device, you must use physical routed interfaces for the interconnection.
Use of the vPC peer-gateway feature does not change this requirement.
Peer-Keepalive Link and Messages
The Cisco NX-OS software uses the peer-keepalive link between the vPC peers to transmit periodic,
configurable keepalive messages. You must have Layer 3 connectivity between the peer devices to transmit
these messages; the system cannot bring up the vPC peer link unless the peer-keepalive link is already up and
running.
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Note
We recommend that you associate the vPC peer-keepalive link to a separate VRF mapped to a Layer 3
interface in each vPC peer device. If you do not configure a separate VRF, the system uses the management
VRF and management ports by default. Do not use the peer link itself to send and receive vPC
peer-keepalive messages.
If one of the vPC peer devices fails, the vPC peer device on the other side of the vPC peer link senses the
failure by not receiving any peer-keepalive messages. The default interval time for the vPC peer-keepalive
message is 1 second, and you can configure the interval between 400 milliseconds and 10 seconds.
You can configure a hold-timeout value with a range of 3 to 10 seconds; the default hold-timeout value is 3
seconds. This timer starts when the vPC peer link goes down. During this hold-timeout period, the secondary
vPC peer device ignores vPC peer-keepalive messages, which ensures that network convergence occurs before
a vPC action takes place. The purpose of the hold-timeout period is to prevent false-positive cases.
You can also configure a timeout value with a range of 3 to 20 seconds; the default timeout value is 5 seconds.
This timer starts at the end of the hold-timeout interval. During the timeout period, the secondary vPC peer
device checks for vPC peer-keepalive hello messages from the primary vPC peer device. If the secondary
vPC peer device receives a single hello message, that device disables all vPC interfaces on the secondary vPC
peer device.
The difference between the hold-timeout and the timeout parameters is as follows:
• During the hold-timeout, the vPC secondary device does not take any action based on any keepalive
messages received, which prevents the system taking action when the keepalive might be received just
temporarily, such as if a supervisor fails a few seconds after the peer link goes down.
• During the timeout, the vPC secondary device takes action to become the vPC primary device if no
keepalive message is received by the end of the configured interval.
See the “Configuring vPCs” section for information about configuring the timer for the keepalive messages.
Note
Ensure that both the source and destination IP addresses used for the peer-keepalive messages are unique
in your network and these IP addresses are reachable from the VRF associated with the vPC peer-keepalive
link.
Use the command-line interface (CLI) to configure the interfaces you are using the vPC peer-keepalive
messages as trusted ports. Leave the precedence at the default (6) or configure it higher. The following is an
example of configuring an interface as a trusted port:
(config)# class-map type qos match-all trust-map
(config-cmap-qos)# match cos 4-7
(config)# policy-map type qos ingresspolicy
(config-pmap-qos)# class trust-map
(config)# interface Ethernet 8/11
(config-if)# service-policy type qos input ingresspolicy
vPC Peer-Gateway
You can configure vPC peer devices to act as the gateway even for packets that are destined to the vPC peer
device’s MAC address.
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Use the peer-gateway command to configure this feature.
Note
You can use the mode auto command to automatically enable this feature. See the “Enabling Certain vPC
Commands Automatically” section for more information about using this command.
Note
The peer-gateway exclude-vlan variation of the command that specifies VLANs to be excluded from
peer-gateway functionality is not supported.
Some network-attached storage (NAS) devices or load balancers might have features that help to optimize
the performances of particular applications. These features enable the device to avoid a routing-table lookup
when responding to a request that originated from a host that is not locally attached to the same subnet. Such
devices might reply to traffic using the MAC address of the sender Cisco Nexus 9000 Series device rather
than the common HSRP gateway. This behavior is noncomplaint with some basic Ethernet RFC standards.
Packets that reach a vPC device for the nonlocal router MAC address are sent across the peer link and could
be dropped by the built in vPC loop avoidance mechanism if the final destination is behind another vPC.
The vPC peer-gateway capability allows a vPC switch to act as the active gateway for packets that are addressed
to the router MAC address of the vPC peer. This feature enables local forwarding of packets without the need
to cross the vPC peer link. In this scenario, the feature optimizes use of the peer link and avoids potential
traffic loss.
Configuring the peer-gateway feature must be done on both primary and secondary vPC peers and is
nondisruptive to the operations of the device or to the vPC traffic. The vPC peer-gateway feature can be
configured globally under the vPC domain submode.
When you enable this feature, Cisco NX-OS automatically disables IP redirects on all interface VLANs
mapped over a vPC VLAN to avoid generation of IP redirect messages for packets switched through the peer
gateway router.
Packets that arrive at the peer-gateway vPC device have their Time to Live (TTL) decremented, so that packets
carrying a TTL of 1 might get dropped in transit due to TTL expiration. You should take this situation into
account when the peer-gateway feature is enabled and particular network protocols that source packets with
a TTL of 1 operate on a vPC VLAN.
vPC Domain
You can use the vPC domain ID to identify the vPC peer links and the ports that are connected to the vPC
downstream devices.
The vPC domain is also a configuration mode that you use to configure the keepalive messages and other
vPC peer link parameters rather than accept the default values. See the “Configuring vPCs” section for more
information about configuring these parameters.
To create a vPC domain, you must first create a vPC domain ID on each vPC peer device using a number
from 1 to 1000. You can have only one vPC domain per VDC.
You must explicitly configure the port channel that you want to act as the peer link on each device. You
associate the port channel that you made a peer link on each device with the same vPC domain ID to form a
single vPC domain. Within this domain, the system provides a loop-free topology and Layer 2 multipathing.
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You can only configure these port channels and vPC peer links statically. All ports in the vPC on each of the
vPC peer devices must be in the same VDC. You can configure the port channels and vPC peer links either
using LACP or no protocol. We recommend that you use LACP with the interfaces in active mode to configure
port channels in each vPC, which ensures an optimized, graceful recovery in a port-channel failover scenario
and provides configuration checks against configuration mismatches among the port channels themselves.
The vPC peer devices use the vPC domain ID that you configure to automatically assign a unique vPC system
MAC address. Each vPC domain has a unique MAC address that is used as a unique identifier for the specific
vPC-related operations, although the devices use the vPC system MAC addresses only for link-scope operations,
such as LACP. We recommend that you create each vPC domain within the contiguous Layer 2 network with
a unique domain ID. You can also configure a specific MAC address for the vPC domain, rather than having
the Cisco NX-OS software assign the address.
See the “vPC and Orphan Ports” section for more information about displaying the vPC MAC table.
After you create a vPC domain, the Cisco NX-OS software creates a system priority for the vPC domain. You
can also configure a specific system priority for the vPC domain.
Note
When manually configuring the system priority, you must ensure that you assign the same priority value
on both vPC peer devices. If the vPC peer devices have different system priority values, vPC does not
come up.
vPC Topology
The following figure shows a basic configuration in which the Cisco Nexus 9000 Series device ports are
directly connected to another switch or host and are configured as part of a port channel that becomes part of
a vPC.
Figure 5: Switch vPC Topology
In the figure, vPC 20 is configured on port channel 20, which has Eth1/10 on the first device and Eth2/1 on
the second as member ports.
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You can configure a vPC from the peer devices through Fabric Extenders (FEXs) as shown in the figure.
Figure 6: FEX Straight-Through Topology (Host vPC)
In the figure, each FEX is single-homed (straight-through FEX topology) with a Cisco Nexus 9000 Series
device. The host interfaces on this FEX are configured as port channels and those port channels are configured
as vPCs. Eth101/1/1 and Eth102/1/5 are configured as members of PO200, and PO200 is configured for vPC
200.
In both topologies, port channels P020 and P0200 must be configured identically on the peer switches and
configuration synchronization is used to synchronize the configurations of the vPC switches.
See the Cisco Nexus 2000 Series NX-OS Fabric Extender Configuration Guide for Cisco Nexus 9000 Series
Switches for more information about configuring FEX ports.
Compatibility Parameters for vPC Interfaces
Many configuration and operational parameters must be identical on all interfaces in the vPC. We recommend
that you configure the Layer 2 port channels that you use for the vPC peer link in trunk mode.
After you enable the vPC feature and configure the peer link on both vPC peer devices, Cisco Fabric Services
(CFS) messages provide a copy of the configuration on the local vPC peer device configuration to the remote
vPC peer device. The system then determines whether any of the crucial configuration parameters differ on
the two devices. (See the “vPC and Orphan Ports” section for more information about CFS.)
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Note
Enter the show vpc consistency-parameters command to display the configured values on all interfaces
in the vPC. The displayed configurations are only those configurations that would limit the vPC peer link
and vPC from coming up.
The compatibility check process for vPCs differs from the compatibility check for regular port channels.
See the “Configuring Port Channels” chapter for information about regular port channels.
Configuration Parameters That Must Be Identical
The configuration parameters in this section must be configured identically on both devices of the vPC peer
link; otherwise, the vPC moves fully or partially into a suspended mode.
Note
You must ensure that all interfaces in the vPC have the identical operational and configuration parameters
listed in this section.
Note
Enter the show vpc consistency-parameters command to display the configured values on all interfaces
in the vPC. The displayed configurations are only those configurations that would limit the vPC peer link
and vPC from coming up.
The devices automatically check for compatibility for some of these parameters on the vPC interfaces. The
per-interface parameters must be consistent per interface, and the global parameters must be consistent globally:
• Port-channel mode: on, off, or active (port-channel mode can, however, be active/passive on each side
of the vPC peer)
• Link speed per channel
• Duplex mode per channel
• Trunk mode per channel:
◦Native VLAN
◦VLANs allowed on trunk
◦Tagging of native VLAN traffic
• Spanning Tree Protocol (STP) mode
• STP region configuration for Multiple Spanning Tree
• Enable/disable state per VLAN
• STP global settings:
◦Bridge Assurance setting
◦Port type setting
◦Loop Guard settings
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• STP interface settings:
◦Port type setting
◦Loop Guard
◦Root Guard
• Maximum Transmission Unit (MTU)
If any of these parameters are not enabled or defined on either device, the vPC consistency check ignores
those parameters.
Note
To ensure that none of the vPC interfaces are in the suspend mode, enter the show vpc brief and show
vpc consistency-parameters commands and check the syslog messages.
Configuration Parameters That Should Be Identical
When any of the following parameters are not configured identically on both vPC peer devices, a
misconfiguration might cause undesirable behavior in the traffic flow:
• MAC aging timers
• Static MAC entries
• VLAN interface—Each device on the end of the vPC peer link must have a VLAN interface configured
for the same VLAN on both ends and they must be in the same administrative and operational mode.
Those VLANs configured on only one device of the peer link do not pass traffic using the vPC or peer
link. You must create all VLANs on both the primary and secondary vPC devices, or the VLAN will
be suspended.
• All ACL configurations and parameters
• Quality of Service (QoS) configuration and parameters
• STP interface settings:
◦BPDU Filter
◦BPDU Guard
◦Cost
◦Link type
◦Priority
◦VLANs (Rapid PVST+)
• Port security
• Cisco Trusted Security (CTS)
• Dynamic Host Configuration Protocol (DHCP) snooping
• Network Access Control (NAC)
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• Dynamic ARP Inspection (DAI)
• IP source guard (IPSG)
• Internet Group Management Protocol (IGMP) snooping
• Hot Standby Routing Protocol (HSRP)
• Protocol Independent Multicast (PIM)
• All routing protocol configurations
To ensure that all the configuration parameters are compatible, we recommend that you display the
configurations for each vPC peer device once you configure the vPC.
Consequences of Parameter Mismatches
You can configure the graceful consistency check feature, which suspends only the links on the secondary
peer device when a mismatch is introduced in a working vPC. This feature is configurable only in the CLI
and is enabled by default.
Use the graceful consistency-check command to configure this feature.
As part of the consistency check of all parameters from the list of parameters that must be identical, the system
checks the consistency of all VLANs.
The vPC remains operational, and only the inconsistent VLANs are brought down. This per-VLAN consistency
check feature cannot be disabled and does not apply to Multiple Spanning Tree (MST) VLANs.
vPC Number
Once you have created the vPC domain ID and the vPC peer link, you create port channels to attach the
downstream device to each vPC peer device. That is, you create one port channel to the downstream device
from the primary vPC peer device and you create another port channel to the downstream device from the
secondary peer device.
Note
We recommend that you configure the ports on the downstream devices that connect to a host or a network
device that is not functioning as a switch or a bridge as STP edge ports.
On each vPC peer device, you assign a vPC number to the port channel that connects to the downstream
device. You will experience minimal traffic disruption when you are creating vPCs. To simplify the
configuration, you can assign the vPC ID number to every port channel to be the same as the port channel
itself (that is, vPC ID 10 for port channel 10).
Note
The vPC number that you assign to the port channel that connects to the downstream device from the vPC
peer device must be identical on both vPC peer devices.
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Moving Other Port Channels into a vPC
Note
You must attach a downstream device using a port channel to both vPC peer devices.
To connect to the downstream device, you create a port channel to the downstream device from the primary
vPC peer device and you create another port channel to the downstream device from the secondary peer device.
On each vPC peer device, you assign a vPC number to the port channel that connects to the downstream
device. You will experience minimal traffic disruption when you are creating vPCs.
Configuring vPC Peer Links and Links to the Core on a Single Module
Note
We recommend that you configure the vPC peer links on dedicated ports of different modules to reduce
the possibility of a failure. For the best resiliency scenario, use at least two modules.
If you must configure all the vPC peer links and core-facing interfaces on a single module, you should configure,
using the command-line interface, a track object and a track list that is associated with the Layer 3 link to the
core and on all vPC peer links on both vPC peer devices. You use this configuration to avoid dropping traffic
if that particular module goes down because when all the tracked objects on the track list go down, the system
does the following:
• Stops the vPC primary peer device sending peer-keepalive messages, which forces the vPC secondary
peer device to take over.
• Brings down all the downstream vPCs on that vPC peer device, which forces all the traffic to be rerouted
in the access switch toward the other vPC peer device.
Once you configure this feature and if the module fails, the system automatically suspends all the vPC links
on the primary vPC peer device and stops the peer-keepalive messages. This action forces the vPC secondary
device to take over the primary role and all the vPC traffic to go to this new vPC primary device until the
system stabilizes.
You should create a track list that contains all the links to the core and all the vPC peer links as its object.
Enable tracking for the specified vPC domain for this track list. Apply this same configuration to the other
vPC peer device. See the Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide for information
about configuring object tracking and track lists.
Note
This example uses Boolean OR in the track list and forces all traffic to the vPC peer device only for a
complete module failure. If you want to trigger a switchover when any core interface or peer link goes
down, use a Boolean AND in the torack list below.
To configure a track list to switch over a vPC to the remote peer when all related interfaces on a single module
fail, follow these steps:
1 Configure track objects on an interface (Layer 3 to core) and on a port channel (vPC peer link).
switch(config-if)# track 35 interface ethernet 8/35 line-protocol
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switch(config-track)# track 23 interface ethernet 8/33 line-protocol
switch(config)# track 55 interface port-channel 100 line-protocol
2 Create a track list that contains all the interfaces in the track list using the Boolean OR to trigger when all
objects fail.
switch(config)# track
switch(config-track)#
switch(config-track)#
switch(config-track)#
switch(config-track)#
44 list boolean OR
object 23
object 35
object 55
end
3 Add this track object to the vPC domain:
switch(config)# vpc domain 1
switch(config-vpc-domain)# track 44
4 Display the track object:
switch# show vpc brief
Legend:
(*) - local vPC is down, forwarding via vPC peer-link
vPC domain id : 1
Peer status : peer adjacency formed ok
vPC keep-alive status : peer is alive
Configuration consistency status: success
vPC role : secondary
Number of vPCs configured : 52
Track object : 44
vPC Peer-link status
--------------------------------------------------------------------id Port Status Active vlans
-- ---- ------ -------------------------------------------------1 Po100 up 1-5,140
vPC status
---------------------------------------------------------------------id Port Status Consistency Reason Active vlans
-- ---- ------ ----------- -------------------------- -----------1 Po1 up success success 1-5,140
This example shows how to display information about the track objects:
switch# show track brief
Track Type Instance Parameter State Last
Change
23 Interface Ethernet8/33 Line Protocol UP 00:03:05
35 Interface Ethernet8/35 Line Protocol UP 00:03:15
44 List ----- Boolean
or UP 00:01:19
55 Interface port-channel100 Line Protocol UP 00:00:34
vPC Interactions with Other Features
vPC and LACP
LACP uses the system MAC address of the vPC domain to form the LACP Aggregation Group (LAG) ID
for the vPC. (See the “Configuring Port Channels” chapter for information about LAG-ID and LACP.)
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You can use LACP on all the vPC port channels, including those channels from the downstream device. We
recommend that you configure LACP with active mode on the interfaces on each port channel on the vPC
peer devices. This configuration allows you to more easily detect compatibility between devices, unidirectional
links, and multihop connection, and provides dynamic reaction to run-time changes and link failures.
We recommend that you manually configure the system priority on the vPC peer link devices to ensure that
the vPC peer link devices have a higher LACP priority than the downstream connected devices. A lower
numerical value system priority means a higher LACP priority.
Note
When manually configuring the system priority, you must ensure that you assign the same priority value
on both vPC peer devices. If the vPC peer devices have different system priority values, vPC does not
come up.
vPC Peer Links and STP
Although vPCs provide a loop-free Layer 2 topology, STP is still required to provide a fail-safe mechanism
to protect against any incorrect or defective cabling or possible misconfiguration. When you first bring up a
vPC, STP reconverges. STP treats the vPC peer link as a special link and always includes the vPC peer link
in the STP active topology.
We recommend that you set all the vPC peer link interfaces to the STP network port type so that Bridge
Assurance is automatically enabled on all vPC peer links. We also recommend that you do not enable any of
the STP enhancement features on vPC peer links. If the STP enhancements are already configured, they do
not cause any problems for the vPC peer links..
When you are running both MST and Rapid PVST+, ensure that the PVST simulation feature is correctly
configured.
See the Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide for information about STP
enhancement features and PVST simulation.
Note
You must configure a list of parameters to be identical on the vPC peer devices on both sides of the vPC
peer link. See the “Compatibility Parameters for vPC Interfaces” section for information about these
required matched settings.
STP is distributed; that is, the protocol continues running on both vPC peer devices. However, the configuration
on the vPC peer device elected as the primary device controls the STP process for the vPC interfaces on the
secondary vPC peer device.
The primary vPC device synchronizes the STP state on the vPC secondary peer device using Cisco Fabric
Services over Ethernet (CFSoE). See the “vPC and Orphan Ports” section for information about CFSoE.
The STP process for vPC also relies on the periodic keepalive messages to determine when one of the connected
devices on the peer link fails. See the “Peer-Keepalive Link and Messages” section for information about these
messages.
The vPC manager performs a proposal/handshake agreement between the vPC peer devices that set the primary
and secondary devices and coordinates the two devices for STP. The primary vPC peer device then controls
the STP protocol on both the primary and secondary devices. We recommend that you configure the primary
vPC peer device as the STP primary root device and configure the secondary VPC device to be the STP
secondary root device.
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If the primary vPC peer device fails over to the secondary vPC peer device, there is no change in the STP
topology.
The BPDUs uses the MAC address set for the vPC for the STP bridge ID in the designated bridge ID field.
The vPC primary device sends these BPDUs on the vPC interfaces.
You must configure both ends of vPC peer link with the identical STP configuration for the following
parameters:
• STP global settings:
◦STP mode
◦STP region configuration for MST
◦Enable/disable state per VLAN
◦Bridge Assurance setting
◦Port type setting
◦Loop Guard settings
• STP interface settings:
◦Port type setting
◦Loop Guard
◦Root Guard
Note
If any of these parameters are misconfigured, the Cisco NX-OS software suspends all interfaces in the
vPC. Check the syslog and enter the show vpc brief command to see if the vPC interfaces are suspended.
Ensure that the following STP interface configurations are identical on both sides of the vPC peer links or
you may see unpredictable behavior in the traffic flow:
• BPDU Filter
• BPDU Guard
• Cost
• Link type
• Priority
• VLANs (PVRST+)
Note
Display the configuration on both sides of the vPC peer link to ensure that the settings are identical.
You can use the show spanning-tree command to display information about the vPC when that feature is
enabled. See the Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide for an example.
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Note
We recommend that you configure the ports on the downstream devices as STP edge ports. You should
configure all host ports connected to a switch as STP edge ports. See the Cisco Nexus 9000 Series NX-OS
Layer 2 Switching Configuration Guide for more information about STP port types.
vPC Peer Switch
The vPC peer switch feature was added to Cisco NX-OS to address performance concerns around STP
convergence. This feature allows a pair of Cisco Nexus 9000 Series devices to appear as a single STP root in
the Layer 2 topology. This feature eliminates the need to pin the STP root to the vPC primary switch and
improves vPC convergence if the vPC primary switch fails.
To avoid loops, the vPC peer link is excluded from the STP computation. In vPC peer switch mode, STP
BPDUs are sent from both vPC peer devices to avoid issues related to STP BPDU timeout on the downstream
switches, which can cause traffic disruption.
This feature can be used with the pure peer switch topology in which the devices all belong to the vPC.
Note
Peer-switch feature is supported on networks that use vPC and STP-based redundancy is not supported.
If the vPC peer-link fail in a hybrid peer-switch configuration, you can lose traffic. In this scenario, the
vPC peers use the same STP root ID as well as the same bridge ID. The access switch traffic is split in
two with half going to the first vPC peer and the other half to the second vPC peer. With peer link failure,
there is no impact to the north/south traffic but the east/west traffic is lost.
See the Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide for information about STP
enhancement features and Rapid PVST+.
vPC and ARP or ND
A feature was added to Cisco NX-OS to address table synchronization across vPC peers using the reliable
transport mechanism of the Cisco Fabric Service over Ethernet (CFSoE) protocol. You must enable the ip
arp synchronize and ipv6 nd synchronize commands to support faster convergence of address tables between
the vPC peers. This convergence overcomes the delay that occurs in ARP table restoration for IPv4 or ND
table restoration for IPv6 when the peer link port channel flaps or when a vPC peer comes back online.
Note
You can use the mode auto command to automatically enable this feature. See the “Enabling Certain vPC
Commands Automatically” section for information about using this command.
vPC Multicast—PIM, IGMP, and IGMP Snooping
The Cisco NX-OS software for the Nexus 9000 Series devices does not support Product Independent Multicast
(PIM), Source-Specific Multicast (SSM) or Bidirectional (BIDR) on a vPC. The Cisco NX-OS software fully
supports PIM Any Source Multicast (ASM) on a vPC.
The software keeps the multicast forwarding state synchronized on both of the vPC peer devices. The IGMP
snooping process on a vPC peer device shares the learned group information with the other vPC peer device
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through the vPC peer link; the multicast states are always synchronized on both vPC peer devices. The PIM
process in vPC mode ensures that only one of the vPC peer devices forwards the multicast traffic to the
receivers.
Each vPC peer is a Layer 2 or Layer 3 device. Multicast traffic flows from only one of the vPC peer devices.
You might see duplicate packets in the following scenarios:
• Orphan hosts
• When the source and receivers are in the Layer 2 vPC cloud in different VLANs with multicast routing
enabled and a vPC member link goes down.
You might see negligible traffic loss in the following scenarios:
• When you reload the vPC peer device that is forwarding the traffic.
• When you restart PIM on the vPC peer device that is forwarding the traffic.
Ensure that you dual-attach all Layer 3 devices to both vPC peer devices. If one vPC peer device goes down,
the other vPC peer device continues to forward all multicast traffic normally.
The following outlines vPC PIM and vPC IGMP/IGMP snooping:
• vPC PIM—The PIM process in vPC mode ensures that only one vPC peer device forwards multicast
traffic. The PIM process in vPC mode synchronizes the source state with both vPC peer devices and
elects which vPC peer device forwards the traffic.
• vPC IGMP/IGMP snooping—The IGMP process in vPC mode synchronizes the designated router (DR)
information on both vPC peer devices. Dual DRs are available for IGMP when you are in vPC mode.
Dual DRs are not available when you are not in vPC mode, because both vPC peer devices maintain the
multicast group information between the peers.
Note
A PIM neighbor relationship between a vPC VLAN (a VLAN that is carried on a vPC peer link) and a
downstream vPC-attached Layer 3 device is not supported, which can result in dropped multicast packets.
If a PIM neighbor relationship is required with a downstream Layer 3 device, a physical Layer 3 interface
must be used instead of a vPC interface.
You should enable or disable IGMP snooping identically on both vPC peer devices, and all the feature
configurations should be identical. IGMP snooping is on by default.
Note
The following commands are not supported in vPC mode:
• ip pim spt-threshold infinity
• ip pim use-shared-tree-only
See the Cisco Nexus 9000 Series NX-OS Multicast Routing Configuration Guide for more information about
multicasting.
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Multicast PIM Dual DR (Proxy DR )
By default, a multicast router sends PIM joins upstream only if it has interested receivers. These interested
receivers can either be IGMP hosts (they communicate through IGMP reports) or other multicast routers (they
communicate through PIM joins).
In the Cisco NX-OS vPC implementation, PIM works in dual designated router (DR) mode. That is, if a vPC
device is a DR on a vPC SVI outgoing interface (OIF), its peer automatically assumes the proxy DR role.
IGMP adds an OIF (the report is learned on that OIF) to the forwarding if the OIF is a DR. With dual DRs,
both vPC devices have an identical (*,G) entry with respect to the vPC SVI OIFs as shown in this example:
VPC Device1:
-----------(*,G)
oif1 (igmp)
VPC Device2:
-----------(*,G)
oif1 (igmp)
IP PIM PRE-BUILD SPT
When the multicast source is in a Layer 3 cloud (outside the vPC domain), one vPC peer is elected as the
forwarder for the source. This forwarder election is based on the metrics to reach the source. If there is a tie,
the vPC primary is chosen as the forwarder. Only the forwarder has the vPC OIFs in its associated (S,G) and
the nonforwarder (S,G) has 0 OIFs. Therefore, only the forwarder sends PIM (S,G) joins toward the source
as shown in this example:
VPC Device1 (say this is Forwarder for Source 'S'):
-----------(*,G)
oif1 (igmp)
(S,G)
oif1 (mrib)
VPC Device2:
-----------(*,G)
oif1 (igmp)
(S,G)
NULL
In the case of a failure (for example, a Layer 3 Reverse Path Forwarding (RPF) link on the forwarder becomes
inoperable or the forwarder gets reloaded), if the current nonforwarder ends up becoming the forwarder, it
has to start sending PIM joins for (S,G) toward the source to pull the traffic. Depending upon the number of
hops to reach the source, this operation might take some time (PIM is a hop-by-hop protocol).
To eliminate this issue and get better convergence, use the ip pim pre-build-spt command. This command
enables PIM send joins even if the multicast route has 0 OIFs. In a vPC device, the nonforwarder sends PIM
(S,G) joins upstream toward the source. The downside is that the link bandwidth upstream from the
nonforwarder gets used for the traffic that is ultimately dropped by it. The benefits that result with better
convergence far outweigh the link bandwidth usage. Therefore, we recommend that you use this command
if you use vPCs.
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vPC Peer Links and Routing
The First Hop Routing Protocols (FHRPs) interoperate with vPCs. The Hot Standby Routing Protocol (HSRP),
and Virtual Router Redundancy Protocol (VRRP) all interoperate with vPCs. We recommend that you
dual-attach all Layer 3 devices to both vPC peer devices.
The primary FHRP device responds to ARP requests, even though the secondary vPC device forwards the
data traffic.
To simplify initial configuration verification and vPC/HSRP troubleshooting, you can configure the primary
vPC peer device with the FHRP active router highest priority.
In addition, you can use the priority command in the if-hsrp configuration mode to configure failover thresholds
for when a group state enabled on a vPC peer link is in standby or in listen state. You can configure lower
and upper thresholds to prevent the interface from going up and down.
VRRP acts similarly to HSRP when running on vPC peer devices. You should configure VRRP the same way
that you configure HSRP.
When the primary vPC peer device fails over to the secondary vPC peer device, the FHRP traffic continues
to flow seamlessly.
We recommend that you configure routing adjacency between the two vPC peer devices to act as a backup
routing path. If one vPC peer device loses Layer 3 uplinks, the vPC can redirect the routed traffic to the other
vPC peer device and leverage its active Layer 3 uplinks.
You can configure the inter-switch link for a backup routing path in the following ways:
• Create a Layer 3 link between the two vPC peer devices.
• Use the non-VPC VLAN trunk with a dedicated VLAN interface.
• Use a vPC peer link with a dedicated VLAN interface.
We do not recommend that you configure the burnt-in MAC address option (use-bia) for HSRP or manually
configure virtual MAC addresses for any FHRP protocol in a vPC environment because these configurations
can adversely affect vPC load balancing. The HSRP use-bia option is not supported on vPCs. When you are
configuring custom MAC addresses, you must configure the same MAC address on both vPC peer devices.
You can use the delay restore command to configure a restore timer that delays the vPC coming back up
until after the peer adjacency forms and the VLAN interfaces are back up. This feature enables you to avoid
packet drops when the routing tables might not be converged before the vPC is once again passing traffic.
Use the delay restore command to configure this feature.
To delay the VLAN interfaces on the restored vPC peer device from coming up, use the interfaces-vlan
option of the delay restore command.
See the Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide for more information about
FHRPs and routing.
Best Practices for Layer 3 and vPC Configuration
This section describes best practices for using and configuring Layer 3 with vPC.
Layer 3 and vPC Configuration Overview
When a Layer 3 device is connected to a vPC domain through a vPC, it has the following views:
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• At Layer 2, the Layer 3 device sees a unique Layer 2 switch presented by the vPC peer devices.
• At Layer 3, the Layer 3 device sees two distinct Layer 3 devices (one for each vPC peer device).
vPC is a Layer 2 virtualization technology, so at Layer 2, both vPC peer devices present themselves as a
unique logical device to the rest of the network.
There is no virtualization technology at Layer 3, so each vPC peer device is seen as a distinct Layer 3 device
by the rest of the network.
The following figure illustrates the two different Layer 2 and Layer 3 views with vPC.
Figure 7: Different Views for vPC Peer Devices
Guidelines for Layer 3 and vPC Configurations
To connect Layer 3 devices to a vPC domain, use Layer 3 links from Layer 3 devices to connect each vPC
peer device.
Note
The vPC loop avoidance rule does not allow the attachment of a Layer 3 device to a vPC domain using a
vPC.
Layer 3 devices are able to initiate Layer 3 routing protocol adjacencies with both vPC peer devices.
One or multiple Layer 3 links can be used to connect a Layer 3 device to each vPC peer device. Cisco Nexus
9000 series devices support Layer 3 Equal Cost Multipathing (ECMP) with up to 16 hardware load-sharing
paths per prefix. Traffic from a vPC peer device to a Layer 3 device can be load-balanced across all the Layer
3 links interconnecting the two devices together.
Using Layer 3 ECMP on the Layer 3 device can effectively use all Layer 3 links from the device to the vPC
domain. Traffic from a Layer 3 device to the vPC domain can be load-balanced across all the Layer 3 links
interconnecting the two entities together.
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The supported connection model for a Layer 3 device to the vPC domain is illustrated in the following figure.
Figure 8: Using Separate Layer 3 Links to Connect L3 Device to a vPC Domain
Follow these guidelines when connecting a Layer 3 device to the vPC domain:
• Use separate Layer 3 links to connect Layer 3 devices to the vPC domain.
• Do not use a Layer 2 vPC to attach a Layer 3 device to a vPC domain unless the Layer 3 device can
statically route to the HSRP address configured on the vPC peer devices.
• When both routed and bridged traffic are required, use individual Layer 3 links for routed traffic and a
separate Layer 2 port-channel for bridged traffic when both routed and bridged traffic are required.
• Enable Layer 3 connectivity between vPC peer device by configuring a VLAN network interface for
the same VLAN from both devices or by using a dedicated Layer 3 link between the two peer devices
(for Layer 3 backup routing path purposes).
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Example Topologies for Layer 3 and vPC
This section contains examples of network topologies for Layer 3 and vPC.
Figure 9: Legend
Peering Between Routers
In this example, vPC is used as a Layer 2 transit path. Because there is no direct routing protocol peering
adjacency from the Layer 3 device to any vPC peer device, this topology is supported.
Figure 10: Peering Between Routers
Peering with an External Router Using Layer 3 Links
This example shows a topology that uses Layer 3 links to connect a Layer 3 device to the vPC domain.
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Note
Interconnecting the 2 entities together in this way is a best practice.
Figure 11: Peering with an External Router Using Layer 3 Links
Peering Between vPC Devices for a Backup Routing Path
This example shows peering between the two vPC peer devices with a Layer 3 backup routed path. If the
Layer 3 uplinks on vPC peer device 1 or vPC peer device 2 fail, the path between the two peer devices is used
to redirect traffic to the switch that has the Layer 3 uplinks in the up state.
The Layer 3 backup routing path can be implemented using a dedicated interface VLAN (such as SVI) over
the vPC peer-link or by using dedicated Layer 2 or Layer 3 links across the two vPC peer devices.
Figure 12: Peering Between vPC Devices for a Backup Routing Path
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Peering Between Two Routers with vPC Devices as Transit Switches
This example is similar to the Peering between Routers topology. The difference here is that the vPC domains
are only used as Layer 2 transit paths.
Figure 13: Peering Between Two Routers with vPC Devices as Transit Switches
Peering with an External Router on Parallel Interconnected Routed Ports
This example shows the Layer 3 device attached to the vPC domain through two different types of links,
Layer 2 links and Layer 3 links.
The Layer 2 links are used for bridged traffic (traffic staying in the same VLAN) or inter-VLAN traffic
(assuming vPC domain hosts the interface VLAN and associated HSRP configuration).
The Layer 3 links are used for routing protocol peering adjacency with each vPC peer device.
The purpose of this topology is to attract specific traffic to go through the Layer 3 device. Layer 3 links are
also used to carry routed traffic from a Layer 3 device to the vPC domain.
Figure 14: Peering with an External Router on Parallel Interconnected Routed Ports
Peering Over a vPC Interconnection on Parallel Interconnected Routed Ports
When routing protocol peering adjacency is required to be established between the two data centers, a best
practice is to add dedicated Layer 3 links between the two sites as shown in this example.
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The vPC link between the two data centers carry bridged traffic or inter-VLAN traffic while the dedicated
Layer 3 links carry the routed traffic across the two sites.
Figure 15: Peering Over a vPC Interconnection on Parallel Interconnected Routed Ports
Peering Over a PC Interconnection and Dedicated Interswitch Link Using non-vPC VLAN
This example shows when the Layer 3 device is single-attached to the vPC domain, you can use a non-vPC
VLAN with a dedicated inter-switch link to establish the routing protocol peering adjacency between the
Layer 3 device and each vPC peer device. However, the non-vPC VLAN must be configured to use a static
MAC that is different than the vPC VLAN.
Note
Configuring the vPC VLAN (and vPC peer-link) for this purpose is not supported.
Figure 16: Peering Over a PC Interconnection and Dedicated Interswitch Link Using non-vPC VLAN
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Virtualization Support
CFSoE
The Cisco Fabric Services over Ethernet (CFSoE) is a reliable state transport mechanism that is used to
synchronize the actions of the vPC peer devices. CFSoE carries messages and packets for many features linked
with vPC, such as STP and IGMP. Information is carried in CFS/CFSoE protocol data units (PDUs).
When you enable the vPC feature, the device automatically enables CFSoE, and you do not have to configure
anything. CFSoE distributions for vPCs do not need the capabilities to distribute over IP or the CFS regions.
You do not need to configure anything for the CFSoE feature to work correctly on vPCs.
The CFSoE transport is local to each VDC.
You can use the show mac address-table command to display the MAC addresses that CFSoE synchronizes
for the vPC peer link.
Note
Do not enter the no cfs eth distribute or the no cfs distribute command. You must enable CFSoE for
vPC functionality. If you do enter either of these commands with vPC enabled, the system displays an
error message.
When you enter the show cfs application command, the output displays “Physical-eth,” which shows the
applications that are using CFSoE.
CFS also transports data over TCP/IP. See the Cisco Nexus 9000 Series NX-OS System Management
Configuration Guide for more information about CFS over IP.
Note
The software does not support CFS regions.
vPC and Orphan Ports
When a device that is not vPC-capable connects to each peer, the connected ports are known as orphan ports
because they are not members of a vPC. The device’s link to one peer will be active (forwarding) and the
other link will be standby (blocking) due to STP.
If a peer link failure or restoration occurs, an orphan port’s connectivity might be bound to the vPC failure or
restoration process. For example, if a device’s active orphan port connects to the secondary vPC peer, the
device loses any connections through the primary peer if a peer link failure occurs and the vPC ports are
suspended by the secondary peer. If the secondary peer were to also suspend the active orphan port, the device’s
standby port becomes active, provides a connection to the primary peer, and restores connectivity. You can
configure in the CLI that specific orphan ports are suspended by the secondary peer when it suspends its vPC
ports and are restored when the vPC is restored.
Virtualization Support
All ports in a given vPC must be in the same VDC. This version of the software supports only one vPC domain
per VDC. You can use the numbers from 1 to 4096 in each VDC to number the vPC.
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vPC Recovery After an Outage
vPC Recovery After an Outage
In a data center outage, both of the Cisco Nexus 9000 Series devices that include a vPC get reloaded.
Occasionally only one peer can be restored. With no functioning peer-keepalive or peer link, the vPC cannot
function normally, but depending on your Cisco NX-OS release, a method might be available to allow vPC
services to use only the local ports of the functional peer.
Autorecovery
You can configure the Cisco Nexus 9000 Series device to restore vPC services when its peer fails to come
online by using the auto-recovery command. You must save this setting in the startup configuration. On
reload, if the peer link is down and three consecutive peer-keepalive messages are lost, the secondary device
assumes the primary STP role and the primary LACP role. The software reinitializes the vPCs, bringing up
its local ports. Because there are no peers, the consistency check is bypassed for the local vPC ports. The
device elects itself to be the STP primary regardless of its role priority and also acts as the master for LACP
port roles.
Note
You can use the mode auto command to automatically enable this feature. See the“Enabling Certain vPC
Commands Automatically” section for information about using this command.
vPC Peer Roles After a Recovery
When the other peer device completes its reload and adjacency forms, the following process occurs:
1 The first vPC peer maintains its current role to avoid any transition reset to other protocols. The peer
accepts the other available role.
2 When an adjacency forms, consistency checks are performed and appropriate actions are taken.
High Availability
During an In-Service Software Upgrade (ISSU), the software reload process on the first vPC device locks its
vPC peer device by using CFS messaging over the vPC communications channel. Only one device at a time
is upgraded. When the first device completes its upgrade, it unlocks its peer device. The second device then
performs the upgrade process, locking the first device as it does so. During the upgrade, the two vPC devices
temporarily run different releases of Cisco NX-OS, however the system functions correctly because of its
backward compatibility support.
Note
See the Cisco Nexus 9000 Series NX-OS High Availability and Redundancy Guide for complete information
about high-availability features.
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Configuring vPCs
vPC Forklift Upgrade Scenario
vPC Forklift Upgrade Scenario
The following describes a scenario for migrating from a pair of Cisco Nexus 9000 Series switches in a vPC
topology to a different pair of Cisco Nexus 9000 Series switches. Typically the scenario might be migrating
from a pair of Cisco Nexus 9508 vPC peer nodes to a pair of Cisco Nexus 9516 switches.
Considerations for a vPC forklift upgrade:
• vPC Role Election and Sticky-bit
When the two vPC systems are joined to form a vPC domain, priority decides which device is the vPC
primary and which is the vPC secondary. When the primary device is reloaded, the system comes back
online and connectivity to the vPC secondary device (now the operational primary) is restored. The
operational role of the secondary device (operational primary) does not change (to avoid unnecessary
disruptions). This behavior is achieved with a sticky-bit, where the sticky information is not saved in
the startup configuration. This method makes the device that is up and running win over the reloaded
device. Hence, the vPC primary becomes the vPC operational secondary. Sticky-bit is also set when a
vPC node comes up with peer-link and peer-keepalive down and it becomes primary after the auto
recovery period.
• vPC Delay Restore
The delay restore timer is used to delay the vPC from coming up on the restored vPC peer device after
a reload when the peer adjacency is already established.
To delay the VLAN interfaces on the restored vPC peer device from coming up, use the interfaces-vlan
option of the delay restore command.
• vPC Auto-Recovery
During a data center power outage when both vPC peer switches go down, if only one switch is restored,
the auto-recovery feature allows that switch to assume the role of the primary switch and the vPC links
come up after the auto-recovery time period. The default auto-recovery period is 240 seconds.
The following example is a migration scenario that replaces vPC peer nodes Node1 and Node2 with New_Node1
and New_Node2.
1
Migration Step
Expected Behavior Node1
Node1
Configured Operational
role ( Ex:
role
role priority
100)
Node2
Node2
Configured Operational
role (Ex:
role
role priority
200)
Initial state
Traffic is
primary
forwarded by both
vPC peers –
Node1 and Node2.
secondary
Node1 is primary
and Node2 is
secondary.
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Primary
Sticky bit:
False
Secondary
Sticky bit:
False
Configuring vPCs
vPC Forklift Upgrade Scenario
Migration Step
2
3
4
Expected Behavior Node1
Node1
Configured Operational
role ( Ex:
role
role priority
100)
Node2 replacement – Traffic converged primary
on Primary vPC
Shut all vPCs and
peer Node1.
uplinks on Node2.
Peer-link and vPC
peer-keepalive are in
administrative up
state.
Primary
Remove Node2.
Primary
Configure
New_Node2. Copy
the configuration to
startup config. vPC
peer-link and
peer-keepalive in
administrative up
state.
Power off
New_Node2.
Node1 will
continue to
forward traffic.
primary
Node2
Node2
Configured Operational
role (Ex:
role
role priority
200)
secondary
Sticky bit:
False
Secondary
Sticky bit:
False
n/a
n/a
secondary
Secondary
Sticky bit:
False
New_Node2 will primary
come up as
secondary. Node1
continue to be
primary.
Primary
Sticky bit:
False
Sticky bit:
False
Traffic will
continue to be
forwarded on
Node01.
Make all connections.
Power on
New_Node2.
5
6
7
Bring up all vPCs
and uplink ports on
New_Node2.
Traffic will be
primary
forwarded by both
Node 1 and
New_Node2.
Node1 replacement - Traffic will
converge on
Shut vPCs and
New_Node2.
uplinks on Node1.
Remove Node1.
primary
New_Node2 will n/a
become secondary,
operational
primary and sticky
bit will be set to
True.
Primary
secondary
Sticky bit:
False
Primary
Sticky bit:
False
secondary
Sticky bit:
False
n/a
Secondary
Secondary
Sticky bit:
False
secondary
Primary
Sticky bit:
True
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Configuring vPCs
Licensing Requirements for vPCs
8
Migration Step
Expected Behavior Node1
Node1
Configured Operational
role ( Ex:
role
role priority
100)
Node2
Node2
Configured Operational
role (Ex:
role
role priority
200)
Configure
New_Node1. Copy
running to startup.
New_Node1 will
come up as
primary,
operational
secondary.
secondary
Power off the new
Node1. Make all
connections. Power
on New_Node1.
9
Note
Bring up all vPCs
and uplink ports on
New_Node1.
primary
Traffic will be
primary
forwarded by both
New Node1 and
new Node2.
Secondary
Sticky bit:
False
Secondary
Sticky bit:
False
Primary
Sticky bit:
True
secondary
Primary
Sticky bit:
True
If you prefer to have the configured secondary node as the operational secondary and the configured
primary as the operational primary, then Node2 can be reloaded at the end of the migration. This is optional
and does not have any functional impact.
Licensing Requirements for vPCs
The following table shows the licensing requirements for this feature:
Product
License Requirement
Cisco NX-OS
Cisco NX-OS vPCs require no license. Any feature not included in a license
package is bundled with the Cisco NX-OS system images and is provided at
no extra charge to you.
Guidelines and Limitations
vPCs have the following configuration guidelines and limitations:
• vPC peers can only operate dissimilar versions of NX-OS software during the upgrade or downgrade
process.
• vPC peers that run different versions out of the upgrade/downgrade period are not supported.
• All ports for a given vPC must be in the same VDC.
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Configuring vPCs
Guidelines and Limitations
• You must enable vPCs before you can configure them.
• You must configure the peer-keepalive link and messages before the system can form the vPC peer link.
• Only Layer 2 port channels can be in vPCs.
• You must configure both vPC peer devices; the configuration is not sent from one device to the other.
• To configure multilayer (back-to-back) vPCs, you must assign unique vPC domain ID for each respective
vPC.
• Check that the necessary configuration parameters are compatible on both sides of the vPC peer link.
See the “Compatibility Parameters for vPC Interfaces” section for information about compatibility
recommendations.
• You might experience minimal traffic disruption while configuring vPCs.
• The software does not support BIDR PIM or SSM on vPCs.
• The software does not support DHCP snooping, DAI, or IPSG in a vPC environment; DHCP Relay is
supported.
• The software does not support CFS regions.
• Port security is not supported on port channels.
• We recommend that you configure all the port channels in the vPC using LACP with the interfaces in
active mode.
• Configure a separate Layer 3 link for routing from the vPC peer devices, rather than using a VLAN
network interface for this purpose.
• Back-to-back, multilayer vPC topologies require unique domain IDs on each respective vPC.
• Layer 3 over vPC configurations are not supported.
• Having the same Hot Standby Router Protocol (HSRP)/Virtual Router Redundancy Protocol (VRRP)
group on all nodes on a double sided vPC is not supported.
• When migrating from a pair of spine nodes to a pair of Cisco Nexus 9000 devices, the HSRP priority
should be configured so that the Cisco Nexus 9000 vPC peers are in Active/Standby state. There is no
support for Cisco Nexus 9000 vPC peers in HSRP state to be in Active/Listen state, Standby/Listen
state, or Listen/Listen state.
• When using vPCs, we recommend that you use default timers for FHRP (HSRP, VRRP), and PIM
configurations. There is no advantage in convergence times when using aggressive timers in vPC
configurations.
• If you configure open shortest path first (OSPF) in a vPC environment, use the following timer commands
in router configuration mode on the core switch to ensure fast OSPF convergence when a vPC peer link
is shut down:
switch (config-router)# timers throttle spf 1 50 50
switch (config-router)# timers lsa-arrival 10
See the Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide for further details about
OSPF.
• BFD for HSRP is not supported in a vPC environment.
• The STP port cost is fixed to 200 in a vPC environment.
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Configuring vPCs
Default Settings
• Jumbo frames are enabled by default on the vPC peer link.
• To accommodate increased traffic when the vPC goes down and traffic needs to cross the peer-link, it
is a best practice to use multiple high bandwidth interfaces (such as the 40G interfaces for the Cisco
Nexus 9000) across linecards for the peer-link.
Default Settings
The following table lists the default settings for vPC parameters.
Table 1: Default vPC Parameters
Parameters
Default
vPC system priority
32667
vPC peer-keepalive message
Disabled
vPC peer-keepalive interval
1 second
vPC peer-keepalive timeout
5 seconds
vPC peer-keepalive UDP port
3200
Configuring vPCs
Note
You must use these procedures on both devices on both sides of the vPC peer link. You configure both
of the vPC peer devices using these procedures.
This section describes how to configure vPCs using the command-line interface (CLI).
Note
If you are familiar with the Cisco IOS CLI, be aware that the Cisco NX-OS commands for this feature
might differ from the Cisco IOS commands that you would use.
Enabling vPCs
You must enable the vPC functionality before you can configure and use vPCs.
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Configuring vPCs
Enabling vPCs
SUMMARY STEPS
1. configure terminal
2. feature vpc
3. exit
4. show feature
5. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
Enables vPCs on the device.
feature vpc
Example:
switch(config)# feature vpc
Step 3
Exits global configuration mode.
exit
Example:
switch(config)# exit
switch#
Step 4
(Optional) Displays which features are enabled on the
device.
show feature
Example:
switch# show feature
Step 5
copy running-config startup-config
(Optional) Copies the running configuration to the
startup configuration.
Example:
switch# copy running-config startup-config
This example shows how to enable the vPC feature:
switch# configure terminal
switch(config)# feature vpc
switch(config)# exit
switch(config)#
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Configuring vPCs
Disabling vPCs
Disabling vPCs
Note
When you disable the vPC functionality, the device clears all the vPC configurations.
SUMMARY STEPS
1. configure terminal
2. no feature vpc
3. exit
4. show feature
5. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
no feature vpc
Disables vPCs on the device.
Example:
switch(config)# no feature vpc
Step 3
exit
Exits global configuration mode.
Example:
switch(config)# exit
switch#
Step 4
show feature
(Optional) Displays which features are enabled on the
device.
Example:
switch# show feature
Step 5
copy running-config startup-config
Example:
switch# copy running-config startup-config
This example shows how to disable the vPC feature:
switch# configure terminal
switch(config)# no feature vpc
switch(config)# exit
switch#
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(Optional) Copies the running configuration to the
startup configuration.
Configuring vPCs
Creating a vPC Domain and Entering vpc-domain Mode
Creating a vPC Domain and Entering vpc-domain Mode
You can create a vPC domain and put the vPC peer link port channels into the identical vPC domain on both
vPC peer devices. Use a unique vPC domain number throughout a single VDC. This domain ID is used to
automatically to form the vPC system MAC address.
You can also use this command to enter vpc-domain command mode.
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. exit
4. show vpc brief
5. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Creates a vPC domain on the device, and enters vpc-domain
configuration mode for configuration purposes. There is
no default; the range is from 1 to 1000.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
Step 3
Exits vpc-domain configuration mode.
exit
Example:
switch(config)# exit
switch#
Step 4
(Optional) Displays brief information about each vPC
domain.
show vpc brief
Example:
switch# show vpc brief
Step 5
(Optional) Copies the running configuration to the startup
configuration.
copy running-config startup-config
Example:
switch# copy running-config startup-config
This example shows how to enter the vpc-domain command mode to configure an existing vPC domain:
switch# configure terminal
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Configuring vPCs
Configuring a vPC Keepalive Link and Messages
switch(config)# vpc domain 5
switch(config-vpc-domain)# exit
switch(config)#
Configuring a vPC Keepalive Link and Messages
Note
You must configure the vPC peer-keepalive link before the system can form the vPC peer link.
You can configure the destination IP for the peer-keepalive link that carries the keepalive messages. Optionally,
you can configure other parameters for the keepalive messages.
Note
We recommend that you configure a separate VRF instance and put a Layer 3 port from each vPC peer
device into that VRF for the vPC peer-keepalive link. Do not use the peer link itself to send vPC
peer-keepalive messages. For information about creating and configuring VRFs, see the Cisco Nexus
9000 Series NX-OS Unicast Routing Configuration Guide. Ensure that both the source and destination
IP addresses use for the peer-keepalive message are unique in your network. The management port and
management VRF are the defaults for these keepalive messages.
Before You Begin
Ensure that you have enabled the vPC feature.
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. peer-keepalive destination ipaddress [hold-timeout secs | interval msecs {timeout secs} | {precedence
{prec-value | network | internet | critical | flash-override | flash | immediate priority | routine}} | tos
{tos-value | max-reliability | max-throughput | min-delay | min-monetary-cost | normal}} |tos-byte
tos-byte-value} | source ipaddress | vrf {name | management vpc-keepalive}]
4. exit
5. show vpc statistics
6. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
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Configuring vPCs
Configuring a vPC Keepalive Link and Messages
Step 2
Command or Action
Purpose
vpc domain domain-id
Creates a vPC domain on the device, and enters vpc-domain
configuration mode.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
Step 3
peer-keepalive destination ipaddress [hold-timeout secs
| interval msecs {timeout secs} | {precedence {prec-value
| network | internet | critical | flash-override | flash |
immediate priority | routine}} | tos {tos-value |
max-reliability | max-throughput | min-delay |
min-monetary-cost | normal}} |tos-byte tos-byte-value}
| source ipaddress | vrf {name | management
vpc-keepalive}]
Example:
switch(config-vpc-domain)# peer-keepalive
destination 172.28.230.85
switch(config-vpc-domain)#
Step 4
Configures the IPv4 address for the remote end of the vPC
peer-keepalive link.
The system does not form the vPC peer link until
you configure a vPC peer-keepalive link.
The management ports and VRF are the defaults.
Note
Note
We recommend that you configure a separate VRF
and use a Layer 3 port from each vPC peer device
in that VRF for the vPC peer-keepalive link. For
more information about creating and configuring
VRFs, see the Cisco Nexus 9000 Series NX-OS
Unicast Routing Configuration Guide.
Exits global configuration mode.
exit
Example:
switch(config)# exit
switch#
Step 5
(Optional) Displays information about the configuration for
the keepalive messages.
show vpc statistics
Example:
switch# show vpc statistics
Step 6
(Optional) Copies the running configuration to the startup
configuration.
copy running-config startup-config
Example:
switch# copy running-config startup-config
For more information about configuring VRFs, see the Cisco Nexus 9000 Series NX-OS Unicast Routing
Configuration Guide.
This example shows how to configure the destination and source IP address and VRF for the vPC-peer-keepalive
link:
switch# configure terminal
switch(config)# vpc domain 100
switch(config-vpc-domain)# peer-keepalive destination 172.168.1.2 source 172.168.1.1 vrf
vpc-keepalive
switch(config-vpc-domain)# exit
switch#
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Configuring vPCs
Creating a vPC Peer Link
Creating a vPC Peer Link
You create the vPC peer link by designating the port channel that you want on each device as the peer link
for the specified vPC domain. We recommend that you configure the Layer 2 port channels that you are
designating as the vPC peer link in trunk mode and that you use two ports on separate modules on each vPC
peer device for redundancy.
Before You Begin
Ensure that you have enabled the vPC feature.
SUMMARY STEPS
1. configure terminal
2. interface port-channel channel-number
3. switchport mode trunk
4. switchport trunk allowed vlan vlan-list
5. vpc peer-link
6. exit
7. show vpc brief
8. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
interface port-channel channel-number
Example:
Selects the port channel that you want to use as the vPC
peer link for this device, and enters interface
configuration mode.
switch(config)# interface port-channel 20
switch(config-if)#
Step 3
switchport mode trunk
(Optional) Configures this interface in trunk mode.
Example:
switch(config-if)# switchport mode trunk
Step 4
switchport trunk allowed vlan vlan-list
Example:
switch(config-if)# switchport trunk
allowed vlan 1-120,201-3967
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(Optional) Configures the permitted VLAN list.
Configuring vPCs
Configuring a vPC Peer-Gateway
Step 5
Command or Action
Purpose
vpc peer-link
Configures the selected port channel as the vPC peer link,
and enters vpc-domain configuration mode.
Example:
switch(config-if)# vpc peer-link
switch(config-vpc-domain)#
Step 6
Exits vpc-domain configuration mode.
exit
Example:
switch(config)# exit
switch#
Step 7
(Optional) Displays information about each vPC,
including information about the vPC peer link.
show vpc brief
Example:
switch# show vpc brief
Step 8
(Optional) Copies the running configuration to the startup
configuration.
copy running-config startup-config
Example:
switch# copy running-config startup-config
This example shows how to configure a vPC peer link:
switch# configure terminal
switch(config)# interface port-channel 20
switch(config-if)# switchport mode
switch(config-if)# switchport mode trunk
switch(config-if)# switchport trunk allowed vlan 1-120,201-3967
switch(config-if)# vpc peer-link
switch(config-vpc-domain)# exit
switch(config)#
Configuring a vPC Peer-Gateway
You can configure vPC peer devices to act as the gateway for packets that are destined to the vPC peer device's
MAC address.
Note
When you attach a Layer 3 device to a vPC domain, the peering of routing protocols using a VLAN also
carried on the vPC peer-link is not supported. If routing protocol adjacencies are needed between vPC
peer devices and a generic Layer 3 device, you must use physical routed interfaces for the interconnection.
Use of the vPC peer-gateway feature does not change this requirement.
Before You Begin
Ensure that you have enabled the vPC feature.
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Configuring vPCs
Configuring a vPC Peer-Gateway
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. peer-gateway
4. exit
5. show vpc brief
6. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Creates a vPC domain if it does not already exist, and
enters vpc-domain configuration mode.
Example:
switch(config-if)# vpc domain 5
switch(config-vpc-domain)#
Step 3
peer-gateway
Enables Layer 3 forwarding for packets destined to the
peer's gateway MAC address.
Example:
switch(config-vpc-domain)# peer-gateway
Note
Step 4
Disable IP redirects on all interface-vlans of this
vPC domain for correct operation of this feature.
exit
Exits vpc-domain configuration mode.
Example:
switch(config)# exit
switch#
Step 5
show vpc brief
(Optional) Displays information about each vPC,
including information about the vPC peer link.
Example:
switch# show vpc brief
Step 6
copy running-config startup-config
Example:
switch# copy running-config startup-config
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(Optional) Copies the running configuration to the
startup configuration.
Configuring vPCs
Configuring a Graceful Consistency Check
Configuring a Graceful Consistency Check
You can configure the graceful consistency check feature, which is enabled by default. Unless this feature is
enabled, the vPC is completely suspended when a mismatch in a mandatory compatibility parameter is
introduced in a working vPC. When this feature is enabled, only the links on the secondary peer device are
suspended. See the “Compatibility Parameters for vPC Interfaces” section for information about consistent
configurations on the vPCs.
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. graceful consistency-check
4. exit
5. show vpc brief
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Creates a vPC domain if it does not already exist, and enters
vpc-domain configuration mode.
Example:
switch(config-if)# vpc domain 5
switch(config-vpc-domain)#
Step 3
Step 4
Example:
Specifies that only the links on the secondary peer device are
suspended when a mismatch is detected in a mandatory
compatibility parameter.
switch(config-vpc-domain)# graceful
consistency-check
Use the no form of this command to disable the feature.
exit
Exits vpc-domain configuration mode.
graceful consistency-check
Example:
switch(config)# exit
switch#
Step 5
show vpc brief
(Optional) Displays information on the vPCs.
Example:
switch# show vpc brief
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Configuring vPCs
Checking the Configuration Compatibility on a vPC Peer Link
This example shows how to enable the graceful consistency check feature:
switch# configure terminal
switch(config)# vpc domain 5
switch(config-vpc-domain)# graceful consistency-check
switch(config-vpc-domain)# exit
switch(config)#
Checking the Configuration Compatibility on a vPC Peer Link
After you have configured the vPC peer link on both vPC peer devices, check that the configurations are
consistent on all vPC interfaces. See the “Compatibility Parameters for vPC Interfaces” section for information
about consistent configurations on the vPCs.
SUMMARY STEPS
1. configure terminal
2. show vpc consistency-parameters {global | interface port-channel channel-number}
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
show vpc consistency-parameters {global | interface
port-channel channel-number}
(Optional) Displays the status of those parameters
that must be consistent across all vPC interfaces.
Example:
switch(config)# show vpc consistency-parameters global
switch(config)#
This example shows how to check that the required configurations are compatible across all the vPC interfaces:
switch# configure terminal
switch(config)# show vpc consistency-parameters global
switch(config)#
Note
Messages regarding the vPC interface configuration compatibility are also logged to the syslog.
Moving Other Port Channels into a vPC
We recommend that you attach the vPC domain downstream port channel to two devices for redundancy.
To connect to the downstream device, you create a port channel from the downstream device to the primary
vPC peer device and you create another port channel from the downstream device to the secondary peer device.
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Configuring vPCs
Moving Other Port Channels into a vPC
On each vPC peer device, you assign a vPC number to the port channel that connects to the downstream
device. You will experience minimal traffic disruption when you are creating vPCs.
Before You Begin
Ensure that you have enabled the vPC feature.
Ensure that you are using a Layer 2 port channel.
SUMMARY STEPS
1. configure terminal
2. interface port-channel channel-number
3. vpc number
4. exit
5. show vpc brief
6. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
interface port-channel channel-number
Example:
Selects the port channel that you want to put into the vPC to
connect to the downstream device, and enters interface
configuration mode.
switch(config)# interface port-channel 20
switch(config-if)#
Step 3
Step 4
vpc number
Example:
Configures the selected port channel into the vPC to connect to
the downstream device. You can use any module in the device
for these port channels. The range is from 1 and 4096.
switch(config-if)# vpc 5
switch(config-vpc-domain)#
Note
exit
Exits vpc-domain configuration mode.
The vPC number that you assign to the port channel
connecting to the downstream device from the vPC peer
device must be identical on both vPC peer devices.
Example:
switch(config)# exit
switch#
Step 5
show vpc brief
(Optional) Displays information on the vPCs.
Example:
switch# show vpc brief
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Enabling Certain vPC Commands Automatically
Step 6
Command or Action
Purpose
copy running-config startup-config
(Optional) Copies the running configuration to the startup
configuration.
Example:
switch# copy running-config startup-config
This example shows how to configure a port channel to connect to the downstream device:
switch# configure terminal
switch(config)# interface port-channel 20
switch(config-if)# vpc 5
switch(config-if)# exit
switch(config)#
Enabling Certain vPC Commands Automatically
You can automatically and simultaneously enable the following commands using the mode auto command:
peer-gateway, auto-recovery, ip arp synchronize, and ipv6 nd synchronize.
Before You Begin
Ensure that you have enabled the vPC feature.
SUMMARY STEPS
1. configure terminal
2. feature vpc
3. vpc domain domain-id
4. [no] mode auto
5. exit
6. exit
7. show running-config vpc
8. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
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Enabling Certain vPC Commands Automatically
Step 2
Command or Action
Purpose
feature vpc
Enables vPCs on the device.
Example:
switch(config)# feature vpc
Step 3
vpc domain domain-id
Creates a vPC domain on the device and enters vpc-domain
configuration mode. The range is from 1 to 1000.
Example:
switch# vpc domain 1
switch(config-vpc-domain)#
Step 4
[no] mode auto
Enables the following commands simultaneously:
peer-gateway, auto-recovery, ip arp synchronize, and
ipv6 nd synchronize.
Example:
Step 5
switch(config-vpc-domain)# mode auto
Use the no form of this command to disable the feature.
exit
Exits vpc-domain configuration mode.
Example:
switch(config-vpc-domain)# exit
switch#
Step 6
Exits global configuration mode.
exit
Example:
switch(config)# exit
switch#
Step 7
(Optional) Displays information about the vPC, including
the commands that are enabled.
show running-config vpc
Example:
switch# show running-config vpc
Step 8
(Optional) Copies the running configuration to the startup
configuration.
copy running-config startup-config
Example:
switch# copy running-config startup-config
This example shows how to simultaneously enable the following commands: peer-gateway, auto-recovery,
ip arp synchronize, and ipv6 nd synchronize.
switch# configure terminal
switch# feature vpc
switch(config)# vpc domain 1
switch(config-vpc-domain)# mode auto
The following commands are executed:
peer-gateway ;
auto-recovery ;
ip arp synchronize ;
ipv6 nd synchronize ;
Warning:
Enables restoring of vPCs in a peer-detached state after reload, will wait for 240 seconds
to determine if peer is un-reachable
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Manually Configuring a vPC Domain MAC Address
switch(config-vpc-domain)# exit
switch(config)# exit
switch# show running-config vpc
!Command: show running-config vpc
!Time: Thu Feb 18 12:31:42 2013
version 6.2(2)
feature vpc
vpc domain 1
peer-gateway
auto-recovery
ip arp synchronize
ipv6 nd synchronize
Manually Configuring a vPC Domain MAC Address
When you create a vPC domain, the Cisco NX-OS software automatically creates a vPC system MAC address,
which is used for operations that are confined to the link-scope, such as LACP. However, you might choose
to configure the vPC domain MAC address manually.
Before You Begin
Ensure that you have enabled the vPC feature.
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. system-mac mac-address
4. exit
5. show vpc role
6. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
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Enters the vPC domain number that you want to
configure. The system enters vpc-domain configuration
mode.
Configuring vPCs
Manually Configuring the System Priority
Step 3
Command or Action
Purpose
system-mac mac-address
Enters the MAC address that you want for the specified
vPC domain in the following format: aaaa.bbbb.cccc.
Example:
switch(config-vpc-domain)# system-mac
23fb.4ab5.4c4e
switch(config-vpc-domain)#
Step 4
Exits vpc-domain configuration mode.
exit
Example:
switch(config-vpc-domain)# exit
switch#
Step 5
(Optional) Displays the vPC system MAC address.
show vpc role
Example:
switch# show vpc brief
Step 6
(Optional) Copies the running configuration to the startup
configuration.
copy running-config startup-config
Example:
switch# copy running-config startup-config
This example shows how to manually configure a vPC domain MAC address:
switch# configure terminal
switch(config)# vpc domain 5
switch(config-vpc-domain)# system-mac 13gb.4ab5.4c4e
switch(config-vpc-domain)# exit
switch(config)#
Manually Configuring the System Priority
When you create a vPC domain, the system automatically creates a vPC system priority. However, you can
also manually configure a system priority for the vPC domain.
Note
We recommend that you manually configure the vPC system priority when you are running LACP to
ensure that the vPC peer devices are the primary devices on LACP. When you manually configure the
system priority, ensure that you configure the same priority value on both vPC peer devices. If these values
do not match, vPC does not come up.
Before You Begin
Ensure that you have enabled the vPC feature.
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Manually Configuring the System Priority
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. system-priority priority
4. exit
5. show vpc role
6. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Enters the vPC domain number that you want to configure.
The system enters vpc-domain configuration mode.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
Step 3
system-priority priority
Example:
Enters the system priority that you want for the specified
vPC domain. The range of values is from 1 to 65535. The
default value is 32667.
switch(config-vpc-domain)# system-priority 4000
switch(config-vpc-domain)#
Step 4
Exits vpc-domain configuration mode.
exit
Example:
switch(config-vpc-domain)# exit
switch#
Step 5
show vpc role
(Optional) Displays the vPC system priority.
Example:
switch# show vpc role
Step 6
copy running-config startup-config
(Optional) Copies the running configuration to the startup
configuration.
Example:
switch# copy running-config startup-config
This example shows how to manually configure the vPC domain system priority:
switch# configure terminal
switch(config)# vpc domain 5
switch(config-vpc-domain)# system-priority 4000
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Manually Configuring the vPC Peer Device Role
switch(config-vpc-domain)# exit
switch(config)#
Manually Configuring the vPC Peer Device Role
By default, the Cisco NX-OS software elects a primary and secondary vPC peer device after you configure
the vPC domain and both sides of the vPC peer link. However, you might want to elect a specific vPC peer
device as the primary device for the vPC. Then, you would manually configure the role value for the vPC
peer device that you want as the primary device to be lower than the other vPC peer device.
vPCs do not support role preemption. If the primary vPC peer device fails, the secondary vPC peer device
takes over to become operationally the vPC primary device. However, the original operational roles are not
restored if the formerly primary vPC comes up again.
Before You Begin
Ensure that you have enabled the vPC feature.
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. role priority priority
4. exit
5. show vpc role
6. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Enters the vPC domain number that you want to configure.
The system enters vpc-domain configuration mode.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
Step 3
role priority priority
Example:
switch(config-vpc-domain)# role priority 4
switch(config-vpc-domain)#
Enters the role priority that you want for the vPC system
priority. The range of values is from 1 to 65636, and the
default value is 32667. A lower value means that this switch
has a better chance of being the primary vPC.
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Configuring the Tracking Feature on a Single-Module vPC
Step 4
Command or Action
Purpose
exit
Exits vpc-domain configuration mode.
Example:
switch(config)# exit
switch#
Step 5
show vpc role
(Optional) Displays the vPC system priority.
Example:
switch# show vpc role
Step 6
copy running-config startup-config
(Optional) Copies the running configuration to the startup
configuration.
Example:
switch# copy running-config startup-config
This example shows how to manually configure the role priority of the vPC peer device:
switch# configure terminal
switch(config)# vpc domain 5
switch(config-vpc-domain)# role priority 4
switch(config-vpc-domain)# exit
switch(config)#
Configuring the Tracking Feature on a Single-Module vPC
If you must configure all the vPC peer links and core-facing interfaces on a single module, you should configure
a track object and a track list that is associated with the Layer 3 link to the core and on all the links on the
vPC peer link on both primary vPC peer devices. Once you configure this feature and if the primary vPC peer
device fails, the system automatically suspends all the vPC links on the primary vPC peer device. This action
forces all the vPC traffic to the secondary vPC peer device until the system stabilizes.
You must put this configuration on both vPC peer devices. Additionally, you should put the identical
configuration on both vPC peer devices because either device can become the operationally primary vPC peer
device.
Before You Begin
Ensure that you have enabled the vPC feature.
Ensure that you have configured the track object and the track list. Ensue that you assign all interfaces that
connect to the core and to the vPC peer link to the track-list object on both vPC peer devices.
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Configuring the Tracking Feature on a Single-Module vPC
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. track track-object-id
4. exit
5. show vpc brief
6. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Enters the vPC domain number that you want to configure,
and enters vpc-domain configuration mode.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
Step 3
track track-object-id
Example:
switch(config-vpc-domain)# track object 23
switch(config-vpc-domain)#
Step 4
Adds the previously configured track-list object with its
associated interfaces to the vPC domain. See the Cisco Nexus
9000 Series NX-OS Unicast Routing Configuration Guide for
information about configuring object tracking and track lists.
Exits vpc-domain configuration mode.
exit
Example:
switch(config-vpc-domain)# exit
switch#
Step 5
(Optional) Displays information about the tracked objects.
show vpc brief
Example:
switch# show vpc brief
Step 6
(Optional) Copies the running configuration to the startup
configuration.
copy running-config startup-config
Example:
switch# copy running-config startup-config
This example shows how to put the previously configured track-list object into the vPC domain on the vPC
peer device:
switch# configure terminal
switch(config)# vpc domain 5
switch(config-vpc-domain)# track object 5
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Configuring vPCs
Configuring for Recovery After an Outage
switch(config-vpc-domain)# exit
switch(config)#
Configuring for Recovery After an Outage
If an outage occurs, the vPC waits for a peer adjacency to form on a switch reload. This situation can result
in an unacceptably long service disruption. You can configure the Cisco Nexus 9000 Series device to restore
vPC services when its peer fails to come on line.
Configuring Reload Restore
The reload restore command and procedure described in this section is deprecated. We recommend that you
use the auto-recovery command and procedure described in the “Configuring an Autorecovery” section.
You can configure the Cisco Nexus 9000 Series device to restore vPC services when its peer fails to come
online by using the reload restore command.
Before You Begin
Ensure that you have enabled the vPC feature.
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. reload restore [delay time-out]
4. exit
5. show running-config vpc
6. show vpc consistency-parameters interface port-channel number
7. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Enters the vPC domain number that you want to configure,
and enters vpc-domain configuration mode.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
Step 3
reload restore [delay time-out]
Example:
Configures the vPC to assume its peer is not functional and to
bring up the vPC. The default delay is 240 seconds. You can
configure a time-out delay from 240 to 3600 seconds.
switch(config-vpc-domain)# reload restore
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Configuring for Recovery After an Outage
Command or Action
Purpose
Use the no form of the command to reset the vPC to its default
settings.
Step 4
Exits vpc-domain configuration mode.
exit
Example:
switch(config-vpc-domain)# exit
switch#
Step 5
(Optional) Displays information about the vPC, specifically
the reload status.
show running-config vpc
Example:
switch# show running-config vpc
Step 6
show vpc consistency-parameters interface
port-channel number
(Optional) Displays information about the vPC consistency
parameters for the specified interface.
Example:
switch# show vpc consistency-parameters
interface port-channel 1
Step 7
copy running-config startup-config
(Optional) Copies the running configuration to the startup
configuration.
Example:
Note
switch# copy running-config startup-config
To ensure the reload feature is enabled, you should
perform this step.
This example shows how to set the vPC reload restore feature and save it in the switch startup configuration:
switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# vpc domain 5
switch(config-vpc-domain)# reload restore
Warning:
Enables restoring of vPCs in a peer-detached state after reload, will wait for 240
seconds (by default) to determine if peer is un-reachable
switch(config-vpc-domain)# exit
switch(config)# exit
switch# copy running-config startup-config
switch# show running-config vpc
!Command: show running-config vpc
!Time: Wed Mar 24 18:43:54 2010
version 5.0(2)
feature vpc
logging level vpc 6
vpc domain 5
reload restore
This example shows how to examine the consistency parameters:
switch# show vpc consistency-parameters interface port-channel 1
Legend:
Type 1 : vPC will be suspended in case of mismatch
Name Type Local Value Peer Value
------------- ---- ----------- --------------STP Port Type 1 Default -
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Configuring for Recovery After an Outage
STP Port Guard 1 None STP MST Simulate PVST 1 Default mode 1 on Speed 1 1000 Mb/s Duplex 1 full Port Mode 1 trunk Native Vlan 1 1 MTU 1 1500 Allowed VLANs - 1-3967,4048-4093
Local suspended VLANs
Configuring an Autorecovery
You can configure the Cisco Nexus 9000 Series device to restore vPC services when its peer fails to come
online by using the auto-recovery command.
Before You Begin
Ensure that you have enabled the vPC feature.
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. auto-recovery [reload-delay time]
4. exit
5. show running-config vpc
6. show vpc consistency-parameters interface port-channel number
7. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Enters the vPC domain number that you want to configure, and
enters vpc-domain configuration mode.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
Step 3
auto-recovery [reload-delay time]
Example:
switch(config-vpc-domain)# auto-recovery
Configures the vPC to assume its peer is not functional and to
bring up the vPC, and specifies the time to wait after a reload
to restore the vPC. The default delay is 240 seconds. You can
configure a delay from 240 to 3600 seconds.
Use the no form of the command to reset the vPC to its default
settings.
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Configuring the Suspension of Orphan Ports
Step 4
Command or Action
Purpose
exit
Exits vpc-domain configuration mode.
Example:
switch(config-vpc-domain)# exit
switch#
Step 5
(Optional) Displays information about the vPC, specifically the
reload status.
show running-config vpc
Example:
switch# show running-config vpc
Step 6
show vpc consistency-parameters interface
port-channel number
(Optional) Displays information about the vPC consistency
parameters for the specified interface.
Example:
switch# show vpc consistency-parameters
interface port-channel 1
Step 7
copy running-config startup-config
(Optional) Copies the running configuration to the startup
configuration.
Example:
Note
switch# copy running-config startup-config
To ensure the autorecovery feature is enabled, you
should perform this step.
This example shows how to set the vPC autorecovery feature and save it in the switch startup configuration:
switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# vpc domain 5
switch(config-vpc-domain)# auto-recovery
Warning:
Enables restoring of vPCs in a peer-detached state after reload, will wait for 240
seconds to determine if peer is un-reachable
switch(config-vpc-domain)# exit
switch(config)# exit
switch# copy running-config startup-config
Configuring the Suspension of Orphan Ports
When a device that is not vPC-capable connects to each peer, the connected ports are known as orphan ports
because they are not members of a vPC. You can explicitly declare physical interfaces as orphan ports to be
suspended (shut down) by the secondary peer when it suspends its vPC ports in response to a peer link or
peer-keepalive failure. The orphan ports are restored when the vPC is restored.
Note
You can configure vPC orphan port suspension only on physical ports, not on port channel member ports.
Before You Begin
Ensure that you have enabled the vPC feature.
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Configuring the Suspension of Orphan Ports
SUMMARY STEPS
1. configure terminal
2. show vpc orphan-ports
3. interface type slot/port
4. vpc orphan-ports suspend
5. exit
6. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
show vpc orphan-ports
(Optional) Displays a list of the orphan ports.
Example:
switch# show vpc orphan-ports
Step 3
interface type slot/port
Specifies an interface to configure, and enters interface
configuration mode.
Example:
switch(config)# interface ethernet 3/1
switch(config-if)#
Step 4
vpc orphan-ports suspend
Example:
Configures the selected interface as a vPC orphan port
to be suspended by the secondary peer in the case of a
vPC failure.
switch(config-if)# vpc orphan-ports suspend
Step 5
Exits interface configuration mode.
exit
Example:
switch(config-if)# exit
switch#
Step 6
copy running-config startup-config
(Optional) Copies the running configuration to the startup
configuration.
Example:
switch# copy running-config startup-config
This example shows how to configure an interface as a vPC orphan port to be suspended by the secondary
peer in the case of a vPC failure:
switch# configure terminal
switch(config)# interface ethernet 3/1
switch(config-if)# vpc orphan-ports suspend
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Configuring the vPC Peer Switch
switch(config-if)# exit
switch(config)#
Configuring the vPC Peer Switch
You can configure the Cisco Nexus 9000 Series device to make a pair of vPC devices appear as a single STP
root in the Layer 2 topology.
Configuring a Pure vPC Peer Switch Topology
You can configure a pure vPC peer switch topology by using the peer-switch command and then setting the
best possible (lowest) spanning tree bridge priority value.
Before You Begin
Ensure that you have enabled the vPC feature.
Note
When using a non-VPC dedicated trunk link between the VPC peers, the non-VPC VLANs should have
a different global priority on the peers to prevent STP from blocking the VLANs.
SUMMARY STEPS
1. configure terminal
2. vpc domain domain-id
3. peer-switch
4. spanning-tree vlan vlan-range priority value
5. exit
6. show spanning-tree summary
7. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
vpc domain domain-id
Enters the vPC domain number that you want to configure,
and enters vpc-domain configuration mode.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
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Configuring the vPC Peer Switch
Step 3
Command or Action
Purpose
peer-switch
Enables the vPC switch pair to appear as a single STP root
in the Layer 2 topology.
Example:
Use the no form of the command to disable the peer switch
vPC topology.
switch(config-vpc-domain)# peer-switch
Step 4
spanning-tree vlan vlan-range priority value
Configures the bridge priority of the VLAN. Valid values
are multiples of 4096. The default value is 32768.
Example:
switch(config)# spanning-tree vlan 1
priority 8192
Step 5
Exits vpc-domain configuration mode.
exit
Example:
switch(config-vpc-domain)# exit
switch#
Step 6
show spanning-tree summary
(Optional) Displays a summary of the spanning tree port
states including the vPC peer switch.
Example:
switch# show spanning-tree summary
Step 7
copy running-config startup-config
(Optional) Copies the running configuration to the startup
configuration.
Example:
switch# copy running-config startup-config
This example shows how to configure a pure vPC peer switch topology:
switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# vpc domain 5
switch(config-vpc-domain)# peer-switch
2010 Apr 28 14:44:44 switch %STP-2-VPC_PEERSWITCH_CONFIG_ENABLED: vPC peer-switch
configuration is enabled. Please make sure to configure spanning tree "bridge" priority as
per recommended guidelines to make vPC peer-switch operational.
switch(config-vpc-domain)# spanning-tree vlan 1 priority 8192
switch(config-vpc-domain)# exit
switch(config)#
Configuring a Hybrid vPC Peer Switch Topology
You can configure a hybrid vPC and non-vPC peer switch topology by using the spanning-tree
pseudo-information command to change the designated bridge ID so that it meets the STP VLAN-based
load-balancing criteria and then change the root bridge ID priority to a value that is better than the best bridge
priority. You then enable the peer switch.
Before You Begin
Ensure that you have enabled the vPC feature.
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Configuring the vPC Peer Switch
When using a non-VPC dedicated trunk link between the VPC peers, the non-VPC VLANs should have a
different pseudo root priority on the peers to prevent STP from blocking the VLANs.
SUMMARY STEPS
1. configure terminal
2. spanning-tree pseudo-information
3. vlan vlan-id designated priority priority
4. vlan vlan-id root priority priority
5. vpc domain domain-id
6. peer-switch
7. exit
8. show spanning-tree summary
9. copy running-config startup-config
DETAILED STEPS
Step 1
Command or Action
Purpose
configure terminal
Enters global configuration mode.
Example:
switch# configure terminal
switch(config)#
Step 2
Configures the spanning tree pseudo information.
spanning-tree pseudo-information
Example:
switch(config)# spanning-tree pseudo-information
switch(config-pseudo)#
Step 3
vlan vlan-id designated priority priority
Configures the designated bridge priority of the VLAN.
Valid values are multiples of 4096 from 0 to 61440.
Example:
switch(config-pseudo)# vlan 1 designated
priority 8192
Step 4
vlan vlan-id root priority priority
Configures the root bridge priority of the VLAN. Valid
values are multiples of 4096 from 0 to 61440.
Example:
switch(config-pseudo)# vlan 1 root
priority 4096
Step 5
vpc domain domain-id
Enters the vPC domain number that you want to configure,
and enters vpc-domain configuration mode.
Example:
switch(config)# vpc domain 5
switch(config-vpc-domain)#
Step 6
peer-switch
Enables the vPC switch pair to appear as a single STP root
in the Layer 2 topology.
Example:
Use the no form of the command to disable the peer switch
vPC topology.
switch(config-vpc-domain)# peer-switch
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Configuring vPCs
Verifying the vPC Configuration
Step 7
Command or Action
Purpose
exit
Exits vpc-domain configuration mode.
Example:
switch(config-vpc-domain)# exit
switch#
Step 8
show spanning-tree summary
(Optional) Displays a summary of the spanning tree port
states including the vPC peer switch.
Example:
switch# show spanning-tree summary
Step 9
copy running-config startup-config
(Optional) Copies the running configuration to the startup
configuration.
Example:
switch# copy running-config startup-config
This example shows how to configure a hybrid vPC peer switch topology:
switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# spanning-tree pseudo-information
switch(config-pseudo)# vlan 1 designated priority 8192
switch(config-pseudo)# vlan 1 root priority 4096
switch(config-pseudo)# vpc domain 5
switch(config-vpc-domain)# peer-switch
switch(config-vpc-domain)# exit
switch(config)#
Verifying the vPC Configuration
To display vPC configuration information, perform one of the following tasks:
Command
Purpose
show feature
Displays whether the vPC is enabled or not.
show vpc brief
Displays brief information about the vPCs.
show vpc consistency-parameters
Displays the status of those parameters that must be
consistent across all vPC interfaces.
show running-config vpc
Displays running configuration information for vPCs.
show port-channel capacity
Displays how many port channels are configured and
how many are still available on the device.
show vpc statistics
Displays statistics about the vPCs.
show vpc peer-keepalive
Displays information about the peer-keepalive
messages.
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Monitoring vPCs
Command
Purpose
show vpc role
Displays the peer status, the role of the local device,
the vPC system MAC address and system priority,
and the MAC address and priority for the local vPC
device.
Monitoring vPCs
Use the show vpc statistics command to display vPC statistics.
Note
This command displays the vPC statistics only for the vPC peer device that you are working on.
Configuration Examples for vPCs
The following example shows how to configure vPC on device A as shown in the figure:
Figure 17: vPC Configuration Example
1 Enable vPC and LACP.
switch# configure terminal
switch(config)# feature vPC
switch(config)# feature lacp
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Configuration Examples for vPCs
2 (Optional) Configure one of the interfaces that you want to be a peer link in the dedicated port mode.
switch(config)# interface ethernet 7/1,
ethernet 7/3, ethernet 7/5. ethernet 7/7
switch(config-if)# shutdown
switch(config-if)# exit
switch(config)# interface ethernet 7/1
switch(config-if)# rate-mode dedicated
switch(config-if)# no shutdown
switch(config-if)# exit
switch(config)#
3 (Optional) Configure the second, redundant interface that you want to be a peer link in the dedicated port
mode.
switch(config)# interface ethernet 7/2, ethernet 7/4,
ethernet 7/6. ethernet 7/8
switch(config-if)# shutdown
switch(config-if)# exit
switch(config)# interface ethernet 7/2
switch(config-if)# rate-mode dedicated
switch(config-if)# no shutdown
switch(config-if)# exit
switch(config)#
4 Configure the two interfaces (for redundancy) that you want to be in the peer link to be an active Layer 2
LACP port channel.
switch(config)# interface ethernet 7/1-2
switch(config-if)# switchport
switch(config-if)# switchport mode trunk
switch(config-if)# switchport trunk allowed vlan 1-50
switch(config-if)# switchport trunk native vlan 20
switch(config-if)# channel-group 20 mode active
switch(config-if)# exit
5 Create and enable the VLANs.
switch(config)# vlan 1-50
switch(config-vlan)# no shutdown
switch(config-vlan)# exit
6 Create a separate VRF for the vPC peer-keepalive link and add a Layer 3 interface to that VRF.
switch(config)# vrf context pkal
switch(config-vrf)# exit
switch(config)# interface ethernet 8/1
switch(config-if)# vrf member pkal
switch(config-if)# ip address 172.23.145.218/24
switch(config-if)# no shutdown
switch(config-if)# exit
7 Create the vPC domain and add the vPC peer-keepalive link.
switch(config)# vpc domain 1
switch(config-vpc-domain)# peer-keepalive
destination 172.23.145.217 source 172.23.145.218 vrf pkal
switch(config-vpc-domain)# exit
8 Configure the vPC peer link.
switch(config)# interface port-channel 20
switch(config-if)# switchport mode trunk
switch(config-if)# switchport trunk allowed vlan 1-50
switch(config-if)# vpc peer-link
switch(config-if)# exit
switch(config)#
9 Configure the interface for the port channel to the downstream device of the vPC.
switch(config)# interface ethernet 7/9
switch(config-if)# switchport mode trunk
switch(config-if)# allowed vlan 1-50
switch(config-if)# native vlan 20
switch(config-if)# channel-group 50 mode active
switch(config-if)# exit
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Related Documents
switch(config)# interface port-channel 50
switch(config-if)# vpc 50
switch(config-if)# exit
switch(config)#
10 Save the configuration.
switch(config)# copy running-config startup-config
Note
If you configure the port channel first, ensure that it is a Layer 2 port channel.
Related Documents
Related Topic
Related Topic
System management
System management
High availability
High availability
Release Notes
Release Notes
Cisco Nexus 9000 Series NX-OS Interfaces Configuration Guide, Release 6.x
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Configuring vPCs
Related Documents
Cisco Nexus 9000 Series NX-OS Interfaces Configuration Guide, Release 6.x
68
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