Posted on September 20, 2019 5:16 pm
 |  Asked by Jeff Lewis
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Hello Team,

I am configuring arista 720XP switch by connecting a cisco VOIP phone to it and an endpoint connected behind to phone.
Configured the port something like below but still the endpoint behind the phone always getting IP from data vlan (29) but not voice vlan (30).

Arista 720XP ———–voip phone———endpoint

Port configuration :
arista-720XP#show running-config interfaces Ethernet 2
interface Ethernet2
description port2
switchport trunk native vlan 29
switchport phone vlan 30
switchport mode trunk phone

Please let me know what else i am missing in config ? Also in arista cannot access port configured with both data & voice vlans ? Always should it be trunk , if data & voice to be configured on it?

Posted by Sarah Howell
Answered on September 20, 2019 6:04 pm

Hi Jeff,

I just published an article on this called “Configuring the Campus Voice VLAN”. Please take a quick look and let me know if you find it helpful or not.

But quickly, is your IP Phone VLAN-aware or unaware (i.e. sending tagged or untagged packets)? Also, is LLDP enabled?

After reading the article and letting me know the above, we can take a deeper look – we can run a tcpdump on the interface to see what is happening.

# bash tcpdump -nevvi et2 ether dst host 08:80:c2:00:00:0e

This will show us the information being sent in the LLDP messages. You can also check “show neighbor classification [mac|interface|] and make sure the switch is classifying the IP phone as such.


Hi Jeff,

Here’s the article/TOI link my colleague Sarah has explained in-detail:


Shreyas Ruwala
Technical Solutions Engineer – Arista Networks
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(Shreyas Ruwala at September 20, 2019 7:42 pm)

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