SG 200 Blocking IP phone from Aruba switch

[MicBz]

Hello Cisco Community,

I am have an interesting problem. I have a customer who bought a new Aruba 1830 to plug into a Cisco sg 200 which goes up the chain to a Meraki MX 67 and a PBX. I have 2 VLANs, 1 is the Native VLAN and the other is VLAN 2 for the phones. My computer can get a DHCP address from both VLANS off of the Aruba switch. However, when I plug the phone into the correct access port it will not get an IP. I get a DHCP error. 

The phone works fine if I plug it into the Cisco sg200, but I am wondering if there is something that could be blocking the IP phone coming from the Aruba switch. Any ideas? 

[Flavio Miranda]

Hi

 Cisco SG200 probably is automatically identifying the phone and running the proper configuration on the port (smartports ).  But, usually switches requires you to configure the port with voice vlan command in order to work with properly. Not sure about Aruba but I believe this must be it. 

[MicBz]

Yes, SG 200 is using the smart port to configure the voice VLAN, but why would this stop traffics from a different switch.

To my knowledge a voice VLAN is the same as a regular VLAN. It uses the same .1q tag. Is this not the case?

[Flavio Miranda]

Voice vlan is not the same as regular vlan. Voice vlan allows both IP phone and PC, if connected to the phone, to work.

If you dont have it on the Aruba switch, I recommend you to add.

[Giuseppe Larosa · Accepted solution]

Hello @MicBz ,

in addition to define VLAN 2 as a voice VLAN as suggested by @Flavio Miranda  on the Aruba switch you should enable LLDP MED and / or CDP as these L2 discovery protocols are used to detect IP phones and to pass info to the phone like the voice VLAN ID.

Hope to help

Giuseppe

[MicBz]

Using a voice VLAN and lldp I was able to get the phone to work. Thank you for your help.