Cisco | Ex SERIES | Deploying IP Telephony with EX Series Ethernet Switches - J

APPLICATION NOTE
DEPLOYING IP TELEPHONY
WITH EX SERIES
ETHERNET SWITCHES
Optimizing VoIP Applications with
Juniper Networks Access Switches
Copyright © 2011, Juniper Networks, Inc.
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APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
Table of Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Description and Deployment Scenario—Method 1: VoIP Phones and End Hosts Sharing Ports . . . . . . . . . . . . . . . . . . . . . . . . . 3
VoIP Phones with LLDP-MED Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
VoIP Phones with LLDP-MED Support—Vendor and Model List. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Avaya LLDP-MED VoIP phone models:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Cisco Systems LLDP-MED VoIP phone models:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Nortel LLDP-MED VoIP phone models: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Phones without LLDP-MED Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Using Access Port with Voice VLAN Feature (but without LLDP-MED) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Using Access Port with the Same VLAN ID for Both Voice and Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Using Trunk Port with Native-VLAN Option. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Description and Deployment Scenario—Method 2: Separate Ports for
VoIP Phone and Endpoint Device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Assigning Each Port as Access Port for Different VLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Assigning Both Ports as Access Ports for Data VLAN with Voice VLAN Feature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table of Figures
Figure 1: VoIP phone and end-host machine sharing a switch port. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Figure 2: LLDP and LLDP-MED interaction between EX Series Ethernet Switch and VoIP phone . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3: An EX Series Ethernet Switch sending out LLDP data unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 4: LLDP-MED-capable VoIP phone sending LLDP-MED data unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 5: EX Series Ethernet Switch sending LLDP-MED data unit upon receiving
LLDP-MED-Capable endpoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 6: LLDP-MED-capable VoIP phone in a shared switch-port physical layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 7: LLDP data unit advertised by EX Series Ethernet Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 8: LLDP-MED-capable VoIP phone advertising its capabilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 9: EX Series Ethernet Switch advertising network policy for VoIP phone via LLDP-MED. . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 10: LLDP-MED-capable phone advertising changed network policy per the
EX Series Ethernet Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 11: Access port with voice VLAN feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 12: Both VoIP phone and endpoint device in the same VLAN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 13: Trunk port with Native-VLAN option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 14: Separate ports for VoIP and endpoint device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 15: Each port as access port for different VLAN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 16: Both ports as access ports of data VLAN with voice VLAN feature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
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Copyright © 2011, Juniper Networks, Inc.
APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
Introduction
Juniper Networks® EX Series Ethernet Switches offer a number of features for optimizing IP telephony deployments.
This application note describes how voice over IP (VoIP) phones can be deployed in conjunction with endpoint hosts
such as desktop or laptop computers; provides background information on Link Layer Discovery Protocol (LLDP) and
LLDP-Media Endpoint Discovery (LLDP-MED); and describes the interaction between VoIP phones and EX Series
Ethernet Switches.
Scope
While this document can’t cover all of the physical configurations that are possible on the EX Series, it does present
configuration examples for the most common applications seen today. In particular, this document addresses
configurations relating to:
• VoIP phones and endpoint hosts sharing the same switch port
• Using separate ports for VoIP phones and an endpoint host
This application note applies to the Juniper Networks EX2200, EX3200, EX3300, EX4200, EX6200 and EX8200
Ethernet Switches as solutions for existing and new enterprise IP telephony deployments.
Description and Deployment Scenario—Method 1: VoIP Phones and End Hosts Sharing Ports
The most common enterprise VoIP edge deployment consists of VoIP phones and end-host machines connected in
series and attached to a single switch port. This physical layout reduces switch port requirements by allowing multiple
end user devices to share a connection rather than occupy their own individual switch ports, thereby reducing the total
number of switches deployed, as well as capital and operational expenses.
However, when VoIP phones and end hosts share a switch port, sound quality on an IP phone call will suffer when
large bursts of data traffic create network congestion that leads to packet loss or delay. To overcome this problem, it is
desirable to provide voice traffic with a higher level of service due to its susceptibility to jitter, delay and packet loss.
EX Series
Data
VoIP
Figure 1: VoIP phone and end-host machine sharing a switch port
This is accomplished by separating voice and data traffic into separate broadcast domains or VLANs—an essential
capability for any robust VoIP solution. The EX Series offers a Voice VLAN feature that enables otherwise standard
access ports to accept both untagged (data) and tagged (voice) traffic from directly connected VoIP phones, and
separate these traffic streams into separate VLANs (namely data-VLAN and voip-VLAN).
The EX Series can separate data and voice traffic on the switch port where Voice VLAN is implemented. However, the
phone is still vulnerable to large bursts of data from the attached end host on its own phone port, depending on the
phone’s ability to prioritize its own voice traffic over the end-host data traffic before forwarding both streams to the
switch. To solve this problem, the user can take the “separate port” approach in which the phone and the end host are
connected to separate ports on the switch. This solution is covered in the “Method 2” section of this paper.
VoIP Phones with LLDP-MED Support
Before exploring the actual interaction between VoIP phones and the EX Series, it’s important to understand the
fundamentals of two industry-standard protocols: Link Layer Discovery Protocol (LLDP) and LLDP-Media Endpoint
Discovery (LLDP-MED). This section will provide a brief overview covering the basics of these two protocols.
Copyright © 2011, Juniper Networks, Inc.
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APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
LLDP, also known as IEEE 802.1AB, is a standards-based Layer 2 protocol that allows network devices to advertise and
receive their identity and capabilities on a LAN segment, most of them directly connected. This protocol, developed as
an open standard, was modeled after various vendor-specific proprietary discovery protocols such as Cisco Discovery
Protocol (CDP), Extreme Discovery Protocol (EDP), Nortel Discovery Protocol (NDP) and others. The EX Series has
embraced the open, standards-based LLDP as their Layer 2 discovery protocol.
LLDP-MED is an extension to the IEEE 802.1AB standard published by the Telecommunications Industry Association
(TIA). This standard, ANSI/TIA-1057, is designed to support interoperability between VoIP endpoint devices and other
networking end-devices, focusing mainly on discovery to facilitate information sharing between endpoints and network
infrastructure devices. Some of the benefits of LLDP-MED include:
• Network policy discovery that allows endpoints and switches to advertise their VLAN IDs (for example, voip-VLAN),
Layer 2 Priority and Differentiated Services Code Point (DSCP)
• Power over Ethernet (PoE) management that allows endpoint devices to advertise their actual PoE levels and
enables power sourcing equipment (like switches) to budget their power allocation accordingly
• Inventory management discovery that stores endpoint device information such as vendor, model firmware and
serial number on the switch and makes it accessible to network management systems for inventory reporting
purposes
VoIP Phones with LLDP-MED Support—Vendor and Model List
Some VoIP phone vendors and their respective LLDP-MED-compatible VoIP phones are listed below. The information
in this section, current as of May 2008, has been gathered from publicly available sources such as vendor websites. To
confirm the latest VoIP phones with LLDP-MED support, consult each vendor’s product documentation.
Avaya LLDP-MED VoIP phone models:
• 9600 Series with firmware release 1.2.1
• 4600 Series with firmware release 2.6
Cisco Systems LLDP-MED VoIP phone models:
• 7906G
• 7911G
• 7931G
• 7941G/7941G-GE
• 7942G
• 7945G
• 7961G/7961G-GE
• 7962G
• 7965G
• 7970G/ 7971G-GE
• 7975G
Nortel LLDP-MED VoIP phone models:
While LLDP and LLDP-MED help simplify IP telephony deployments, it is important to understand how they interact
with the VoIP phones and switches—specifically with the EX Series, which will not advertise their capabilities via LLDPMED when a port is first brought online.
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Copyright © 2011, Juniper Networks, Inc.
APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
Figure 2 provides an overview of the LLDP/LLDP-MED message exchange sequence when an LLDP-MED-enabled VoIP
phone is first connected to a switch port on an EX Series Ethernet Switch.
Interface will start advertising Base LLDP
1
LLDP-MED advertisement sent by neighbor
2
EX Series Ethernet Switch will
toggle to LLDP-MED
VoIP
EX Series
3
Figure 2: LLDP and LLDP-MED interaction between EX Series Ethernet Switch and VoIP phone
Figure 3: An EX Series Ethernet Switch sending out LLDP data unit
This interaction can be seen in detail in the highlighted section of the packet capture shown in Figure 3. Note that
LLDP, as defined in IEEE 802.1AB, sends the data unit to a well-known IEEE multicast address (01:80:c2:00:00:0e).
This address is defined within a range of addresses reserved by the IEEE for protocols that are to be confined to an
individual LAN segment.
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APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
On the other hand, LLDP-MED-capable VoIP phones will advertise their capabilities using LLDP-MED from the start.
Note that the fields within the section named TIA indicate LLDP-MED (Figure 4).
Figure 4: LLDP-MED-capable VoIP phone sending LLDP-MED data unit
Upon receiving the LLDP-MED data units from the neighboring end device (VoIP phone), the EX Series will start
advertising its capabilities using LLDP-MED (Figure 5).
Figure 5: EX Series Ethernet Switch sending LLDP-MED data unit upon receiving LLDP-MED-Capable endpoint
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Copyright © 2011, Juniper Networks, Inc.
APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
Using Voice VLAN Support with LLDP-MED
As mentioned earlier, the Voice VLAN feature enables EX Series switches to accept both untagged (data) and tagged
(voice) traffic from directly connected VoIP phones, and split these traffic streams into different VLANs. This feature
delivers its greatest benefit when connected to a VoIP phone capable of advertising and receiving LLDP-MED data
units, including VLAN ID assignments, because it essentially enables the EX Series to deliver a “plug-and-play” IP
telephony solution (Figure 6).
Access Port
with Voice
VLAN feature
LLDP-MED
EX Series
Data
VoIP
Data VLAN 10
Voice VLAN 99
Figure 6: LLDP-MED-capable VoIP phone in a shared switch-port physical layout
The following section details the implementation shown in Figure 6.
The configuration of EX Series switches with the Voice VLAN feature in a typical shared switch-port implementation
with LLDP-MED-capable VoIP phones is as follows:
user@switch# set protocols lldp interface all
user@switch# set protocols lldp-med interface all
user@switch# set vlans voip-only vlan-id 99
user@switch# set vlans data-only vlan-id 10
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching port-mode
access
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan member
data-only
user@switch# set ethernet-switching-options voip interface ge-0/0/1.0 vlan voiponly
user@switch# set ethernet-switching-options voip interface ge-0/0/1.0 forwardingclass expedited-forwarding
user@switch# commit
Although these strings of data may appear overwhelming to someone who is unfamiliar with Juniper Networks Junos®
operating system, the configuration semantics are actually very straightforward. A closer inspection of the individual
functional blocks will help explain what is happening and clarify the benefit of the Voice VLAN feature.
In the first functional block (below), the protocols to be used—LLDP and LLDP-MED—are turned on. Although these
protocols are turned on by default on any EX Series switch, it is specifically called out here for clarification.
user@switch# set protocols lldp interface all
user@switch# set protocols lldp-med interface all
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APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
In the second functional block (below), two VLANs are defined: one for voice and one for data. The actual VLAN IDs
used on this example are arbitrary; the EX Series allows VLAN ID configurations up to 4096.
user@switch# set vlans voip-only vlan-id 99
user@switch# set vlans data-only vlan-id 10
In the third functional block (below), the interface “ge-0/0/1” has been configured as an access port belonging to the
data VLAN (“data-only”). Notice that there is no configuration needed for the voice VLAN, which is covered in the next
section.
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching port-mode
access
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan member
data-only
In the fourth functional block (below), the Voice VLAN feature is configured under the Ethernet-switching-options
stanza with the voip option (see the “ethernet-switching-options voip” command below). Here the actual VLAN to be
used for voice will be defined, as well as the level of service that will be provided for traffic received on that VLAN—in
this example, “expedited-forwarding.”
user@switch# set ethernet-switching-options voip interface ge-0/0/1.0 vlan voiponly
user@switch# set ethernet-switching-options voip interface ge-0/0/1.0 forwardingclass expedited-forwarding
In the fifth functional block (below), the configuration is committed in Junos OS, making it active.
user@switch# commit
Upon completion, the LLDP-MED configuration can be verified on the EX Series, as shown below.
user@switch> show lldp
8
LLDP
Advertisement interval
Transmit delay
Hold timer
Config Trap Interval
Connection Hold timer
:
:
:
:
:
:
LLDP MED
MED fast start count
: Enabled
: 3 Packets
Interface
all
LLDP-MED
Enabled
LLDP
Enabled
Enabled
30 seconds
2 seconds
4 seconds
60 seconds
300 seconds
Copyright © 2011, Juniper Networks, Inc.
APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
Advertisements sent by neighboring VoIP phones can also be viewed. A Cisco VoIP phone was used for the following
example:
user@switch> show lldp neighbors interface ge-0/0/1.0
LLDP Neighbor Information:
Index: 1 Time to live: 180 Time mark: Thu Mar 6 22:35:53 2008 Age: 28 secs
Local interface Chassis type Chassis ID Port type Port ID Port description System name System description :
:
:
:
:
:
:
:
ge-0/0/1.0
Network address
172.16.10.10
Locally assigned
xxxxxxxxxxxx:P1
SW PORT
SEPxxxxxxxxxx
Cisco IP Phone CP-7945G,V1, SIP45.8-3-3SR2S
System capabilities
Supported: Bridge Telephone
Enabled : Bridge Telephone
Management address
Type
: IPv4
Address : 172.16.10.10
Media endpoint class: Class III Device
MED
MED
MED
MED
MED
MED
MED
Hardware revision
Firmware revision
Software revision
Serial number Manufacturer name
Model name
Asset id : CP-7
:
:
:
:
:
:
1
tnp45.8-3-1-21.bin
SIP45.8-3-3SR2Sbin
xxxxxxxxxxxxxxxx
Cisco Systems, Inc.
CP-7945Gstem
By using a packet capture tool, the details of the actual interaction between the EX Series and LLDP-MED-capable
VoIP device can be viewed (see Figures 7 through 10).
Figure 7: LLDP data unit advertised by EX Series Ethernet Switch
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APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
As discussed previously regarding the interaction between LLDP and LLDP-MED, the EX Series will initially advertise its
capabilities using LLDP only, as shown in Figure 7. The LLDP-MED-capable phone will advertise its capabilities using
LLDP-MED, as shown in Figure 8. A Cisco IP phone 7945G was used in the following example.
Figure 8: LLDP-MED-capable VoIP phone advertising its capabilities
Sections preceded with a TIA heading show that the VoIP phone is LLDP-MED-capable; its media capabilities and
network policy can also be viewed. Note that the VLAN ID sent by the VoIP phone shows the voice VLAN ID as 0 with a
Layer 2 (802.1p) priority of 5 for voice traffic and a VLAN ID of 0 with a Layer 2 (802.1p) priority of 4 for voice-signaling
traffic.
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Copyright © 2011, Juniper Networks, Inc.
APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
Figure 9: EX Series Ethernet Switch advertising network policy for VoIP phone via LLDP-MED
Once the EX Series Ethernet Switch determines that the connected device is LLDP-MED-capable, it will advertise
its capabilities and defined network policy via LLDP-MED. In Figure 10, the VLAN ID used for voice is set at 99
as configured.
Figure 10: LLDP-MED-capable phone advertising changed network policy per the EX Series Ethernet Switch
Copyright © 2011, Juniper Networks, Inc.
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APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
The LLDP-MED-capable VoIP phone now sets VLAN ID 99 for both voice and voice-signaling traffic in its LLDP-MED
network policy in response to the LLDP data unit it received previously.
Phones without LLDP-MED Support
While organizations can derive great benefits by using LLDP-MED-capable VoIP phones, the fact is that most existing
VoIP deployments don’t support the protocol, and businesses are unlikely to incur the cost required to upgrade these
devices. In such cases, there are several other IP telephony methods available that the EX Series can support. Each of
these solutions, however, has some unique requirements.
Using Access Port with Voice VLAN Feature (but without LLDP-MED)
Although the Voice VLAN feature delivers the greatest benefit when coupled with LLDP-MED-capable VoIP phones,
it is flexible enough that non-LLDP-MED-capable phones can also use it effectively. However, such a configuration
requires that the Voice VLAN feature be set manually on the VoIP phones themselves, since LLDP-MED is not available
to accomplish this dynamically.
Access Port
with Voice
VLAN feature
Non-LLDP-MED
EX Series
Data
VoIP
Data VLAN 10
VoIP VLAN 99
Figure 11: Access port with voice VLAN feature
Once the Voice VLAN ID and other relevant parameters have been manually set on the VoIP phone to match the
settings configured on the EX Series, the feature behaves the same as it does when configured with LLDP-MEDcapable VoIP phones.
Using Access Port with the Same VLAN ID for Both Voice and Data
Another way to deploy an IP telephony solution is to assign both the VoIP phone and the end-host machine to a single
VLAN. This is the simplest configuration among the methods discussed in this document.
Non-LLDP-MED
EX Series
Data
VLAN 100
VoIP
VLAN 100
Figure 12: Both VoIP phone and endpoint device in the same VLAN
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Copyright © 2011, Juniper Networks, Inc.
APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
The configuration is performed as follows:
user@switch# set vlans voice-and-data vlan-id 100
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching port-mode
access
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan member
voice-and-data
user@switch# commit
Although this method is technically feasible, it is not a recommended configuration because placing both data and
voice traffic on the same VLAN leaves the voice traffic prone to potential jitter, delay and packet loss—conditions that
are introduced by “bursty” data traffic.
Using Trunk Port with Native-VLAN Option
Using a switch trunk port where the VoIP phone and endpoint host are connected will create the desired separation
between voice and data traffic, but it requires some additional configuration on both the switch and the VoIP phone.
Trunk Port with
Native VLANVoIP VLAN
Non-LLDP-MED
EX Series
Data
Untagged
VoIP
VoIP VLAN 99
Figure 13: Trunk port with Native-VLAN option
A sample trunk configuration is provided below:
user@switch# set vlans voip-only vlan-id 99
user@switch# set vlans data-only vlan-id 10
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching port-mode
trunk
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan member
[ voip-only ]
user@switch# set interfaces ge-0/0/1 unit 0 family Ethernet-switching nativevlan-id data-only
user@switch# commit
Let’s look at this particular configuration in greater detail. Similar to the Voice VLAN feature, two VLANs are configured
here: voip-only and data-only.
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching port-mode
trunk
user@switch# set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan member
[ voip-only ]
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APPLICATION NOTE - Deploying IP Telephony with EX Series Ethernet Switches
However, in this case the interface is configured as a trunk that includes only the voice VLAN. In order to separate the
voice and data traffic, the trunk port will transmit and receive only tagged traffic on the trunk VLAN member list, which
in this case is the voip-only VLAN.
Since a typical endpoint host such as a desktop or laptop will send its packets untagged (which will subsequently be
relayed by the VoIP phone), the corresponding switch trunk port must be configured with the “native-vlan-id” option in
order to transmit and receive untagged traffic belonging to the native VLAN, which in this case is the data-only VLAN.
Otherwise, untagged packets sent from the endpoint host and relayed by the phone would be dropped on the switch
trunk port by default, since the packets are untagged.
user@switch# set interfaces ge-0/0/1 unit 0 family Ethernet-switching nativevlan-id data-only
Description and Deployment Scenario—Method 2: Separate Ports for VoIP Phone and Endpoint Device
VoIP
EX Series
Data
Figure 14: Separate ports for VoIP and endpoint device
In contrast to the shared switch-port configuration discussed earlier, VoIP phones (LLDP-MED-capable and noncapable) and endpoint hosts can also occupy their own ports. This is not a typical IP telephony deployment in the
enterprise today, where cost reduction is a priority, but there are cases where endpoint devices would occupy their own
ports, mainly for management, troubleshooting and maintenance purposes.
Assigning Each Port as Access Port for Different VLAN
When attaching VoIP phones and endpoint devices to their own ports, one approach is to assign each port to different
VLANs, so that the port connected to the VoIP phone is configured for voice traffic and the port connected to the
endpoint host is configured for data traffic.
VoIP VLAN 99
VoIP
EX Series
Data
Data VLAN 10
Figure 15: Each port as access port for different VLAN
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Copyright © 2011, Juniper Networks, Inc.
APPLICATION NOTE -Deploying IP Telephony with EX Series Ethernet Switches
This configuration is very straightforward; examples discussed previously in this document can be used as reference.
Furthermore, this method does not require any manual settings on either the VoIP phone or the endpoint host, as they
already belong to the correct domain as soon as they are physically connected.
Assigning Both Ports as Access Ports for Data VLAN with Voice VLAN Feature
Another two-port option is to assign both ports (where the VoIP phone and endpoint host are connected) into the data
VLAN and then configure the Voice VLAN feature. Manual configuration may be required if the VoIP phone is not LLDP-MEDcapable. The actual configuration is very similar to the configuration shown in the Access Port with Voice VLAN section.
VoIP VLAN 99
Access Port
with Voice
VLAN feature
VoIP
EX Series
Data
Data VLAN 10
Figure 16: Both ports as access ports of data VLAN with voice VLAN feature
Conclusion
When implementing an IP telephony solution, there are a number of options to consider before committing to the
actual deployment. This application note has discussed a variety of methods for implementing an IP telephone
solution, including the physical layout of VoIP phones and endpoint devices, the Voice VLAN feature of the EX Series,
LLDP and LLDP-MED, and more. These methods and technologies can and will make a difference in the successful
implementation of an IP telephony solution.
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3500131-003-EN
Sept 2011
Copyright © 2011, Juniper Networks, Inc.
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