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Pass Through (PT) Functionality—Intel
®
82599 10 GbE Controller
Table 10-2 Optional NC-SI Features Support (Continued)
Feature Supported
NC-SI flow control command No
Hardware arbitration No
Details
10.2.2 SMBus Pass Through (PT) Functionality
When operating in SMBus mode, the 82599 provides the following manageability services to the BMC on top of the pass through traffic functionality:
• ARP handling — The 82599 can be programmed to auto-ARP replying for ARP request packets and sending gratuitous ARP to reduce the traffic over the SMBus.
• Teaming and fail-over — The 82599 can be configured to either teaming or nonteaming modes. When operated in teaming mode the 82599 can also provide auto fail-over configurations as detailed in the following sub-sections.
• Default configuration of filters by EEPROM — When working in SMBus mode, the default values of the manageability receive filters can be set according to the PT LAN
) and flex TCO EEPROM structure (
10.2.2.1 Pass Through (PT) Modes
PT configuration depends on how the LAN ports are configured. If the LAN ports are configured as two different channels (non-teaming mode) then the 82599 is presented on the manageability link as two different devices (via two different SMBus addresses) on which each device is connected to a different LAN port. In this mode (the same as in the
LAN channels), there is no logical connection between the two devices. In this mode, the fail-over between the two LAN ports are done by the external BMC (by sending/receiving packets through different devices). The status reports to the BMC, ARP handling, DHCP and other pass through functionality are unique for each port.
When the 82599 operates in teaming mode, it presents itself on the SMBus as a single device. In this mode, the external BMC is not aware that there are two LAN ports. The
82599 determines how to route the packets that it receives on the manageability channel according to the fail-over algorithm. The status reports to the BMC and other pass through configurations are common to both ports.
In pass through mode most of the manageability traffic is handled by the BMC. However, portion of the network traffic can be offloaded and by the 82599 as described in the following sub-sections. This configuration can be done by issuing configuration commands over the SMBus channel or the 82599 can load it from its EEPROM at power up (or both).
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82599 10 GbE Controller—Pass Through (PT) Functionality
10.2.2.2 LAN Fail-Over in LAN Teaming Mode
Manageability fail-over is the ability to detect that the LAN connection on one port is lost, and enable the other port for manageability traffic. When the 82599 operates in teaming mode, the operating system and the external BMC consider it as one logical network device. The decision on which of the 82599 ports are used is done internally by the
82599 (or by the ANS driver in case of the regular receive/transmit traffic). This section deals with fail-over in teaming mode only. In non-teaming mode, the external BMC should consider the 82599's network ports as two different network devices, and the
BMC is solely responsible for the fail-over mechanism.
In teaming mode, the 82599 maps both network ports into a single SMBus slave device.
The 82599 automatically handles the configurations of both network ports. Thus, for configurations, receiving and transmitting the BMC should consider both ports as a single entity.
When the currently active transmission port becomes unavailable (such as the link is down), the 82599 automatically switches transmission to the other port. Thus, as long as one of the ports is valid, the BMC will have a valid link indication for the SMBus slave.
Note:
As both ports might be active (such as with a valid link) packets might be received on the currently non-active port. To avoid packet duplication, failover should not be enabled when connected to a hub.
Note:
Fail over and teaming are not supported in NC-SI mode.
10.2.2.2.1 Port Switching (Fail-Over)
While in teaming mode, transmit traffic is always transmitted by the 82599 through only one of the ports at any given time. The 82599 might switch the traffic transmission between ports under any of the following conditions:
1. The current transmitting port link is not available
2. The preferred primary port is enabled and becomes available for transmission.
10.2.2.2.2 Driver Interactions
When the LAN driver is present, the decision to switch between the two ports is done by the driver. When the driver is absent, this decision is done internally by the 82599.
Note:
When the driver releases teaming mode (such as, when the system state changes), the 82599 reconfigures the LAN ports to teaming mode. The
82599 accomplishes this by re-setting the Ethernet MAC address of the two ports to be the teaming address in order to re-start teaming. This is followed by transmission of gratuitous ARP packets to notify the network of teaming mode re-setting.
810 331520-004
Pass Through (PT) Functionality—Intel
®
82599 10 GbE Controller
10.2.2.2.3 Fail-Over Configuration
Fail-over operation is configured through the fail-over configuration structure (see
The BMC should configure this register after a the 82599 initialization indication
(following a firmware reset). The different configurations available to the BMC are detailed in this section.
Note:
In teaming mode both ports should be configured with the same receive manageability filters parameters (EEPROM sections for port 0 and port 1 should be identical).
Preferred Primary Port
— The BMC might choose one of the network ports (LAN0 or
LAN1) as a preferred primary port for packet transmission. The 82599 always switches to the preferred primary port when it is available.
Gratuitous ARPs
— In order to notify the link partner that a port switching has occurred, the 82599 can be configured to automatically send gratuitous ARPs. These gratuitous ARPs cause the link partner to update its ARP tables to reflect the change. The
BMC might enable/disable gratuitous ARPs, configure the number of gratuitous ARPs or the interval between them by modifying the Fail Over configuration register.
Link Down Timeout
— The BMC can control the timeout for a link to be considered invalid. The 82599 waits this timeout before attempting to switch from an inactive port.
10.2.2.2.4 Fail-Over Structure
The fail-over structure (listed in the following table) is loaded on power up from the
), or through the Set Fail-Over Configuration host command
by the LAN driver (see Section 10.5.3.8
). The bits in this register can also be modified by
the 82599 hardware reflecting its current state.
Field
RMP0EN
RMP1EN
MXP
PRPP
PRPPE
Reserved
RGAEN
Bit(s)
0
1
2
3
4
5
6
RW
RO
RO
RO
RW
RW
RO
RW
Init Val
0x1
Description
RCV MNG port 0 Enable.
When this bit is set, it reports that MNG traffic is received from port 0.
0x1
0x0
0x0
0x0
0x0
0x0
RCV MNG port 1 Enable.
When this bit is set, it reports that MNG traffic is received from port 1.
MNG XMT Port.
0b = MNG traffic should be transmitted through port 0.
1b = MNG traffic should be transmitted through port 1.
Preferred Primary Port.
0b = Port 0 is the preferred primary port.
1b = Port 1 is the preferred primary port.
Preferred Primary Port enables.
Reserved.
Repeated Gratuitous ARP Enable.
If this bit is set, the 82599 sends a configurable number of gratuitous ARP packets (GAC bits of this register) using configurable interval (GATI bits of this register) after the following events: System move to Dx, or fail-over event initiated the 82599.
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Intel
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82599 10 GbE Controller—Pass Through (PT) Functionality
Field
Reserved
Reserved
TFOENODX
Reserved 10-11
GAC
LDFOT
GATI
Bit(s) RW
7 RO
8
9
RO
RW
12-15
16-23
24-31
RO
RW
RW
RW
Init Val
0x0
0x0
0x0
0x0
0x0
Reserved.
Reserved.
Description
Teaming Fail Over Enable on Dx.
Enable fail-over mechanism. Bits 3-8 are valid only if this bit is set.
Reserved.
0x0
0x0
Gratuitous ARP counter.
Counts the number of gratuitous ARP that should be done after a fail-over event and after a move to Dx. When it is set to zero, there is no limit on the gratuitous ARP packets.
Link Down Fail-Over Time.
Defines the time in seconds the link should be down before doing a fail over to the other port.
This is also the time that the primary link should be up (after it was down) before the 82599 switches back to the primary port.
Gratuitous ARP Transmission Interval.
Defines the GAP in seconds before retransmission of gratuitous ARP packets.
10.2.2.3 ARP Handling
Independent of the management interface, the 82599 can be programmed by the BMC to provide ARP services. The 82599 supports auto-ARP replying for ARP request packets and sending Gratuitous ARP. Auto-ARP is done in both ports in either modes: dual-channel and one-channel. In dual-channel mode, each channel uses its own IP and Ethernet MAC address (either the operating system Ethernet MAC address or independent addresses).
In one-channel mode, both ports use the same IP and Ethernet MAC address and the ARP is responded to through the port it was received.
The following ARP parameters are loaded from the EEPROM on power up or configured through the management interface:
• ARP auto-reply enabled
• ARP IP address (to filter ARP packets)
• ARP Ethernet MAC Addresses (for ARP response)
When an ARP request packet is received on the wire and ARP auto-reply is enabled, the
82599 checks the targeted IP address (after the packet has passed L2 checks and ARP checks). If the targeted IP matches the 82599 IP configuration, then it replies with an
ARP response. The 82599 responds to the ARP request targeted to the ARP IP address with its ARP Ethernet MAC address. In a case where there is no match, the 82599 silently discards the packets. If the 82599 is not configured to do auto-ARP response, it forwards the ARP packets to the BMC.
When the external BMC uses the same IP and MAC of the operating system, the ARP operation should be coordinated with the operating system operation. In this mode, the external BMC has the responsibility and ARP auto-reply should be disabled.
Note:
When configured in NC-SI mode, the 82599 does not provide ARP services.
All ARP handling is done by the BMC.
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