I’m still getting used to the Aruba CX switches, as they’re definitely humbling me despite me not being a network “expert” per se. One interesting battle I had recently was trying to get the “PC Ports” on some Mitel IP phones to work. In my case I’m messing with Mitel 5xxx and 6xxx series phones, and while the phones themselves work fine, and the PC ports are enabled, they just…don’t do anything!
The PC ports on these phones are basically a daisy-chain port; they allow an IP phone and a computer to share a single network drop by basically daisy-chaining the computer through the phone.
The suggested method for setting up IP phones is pretty simple – if you have a voip/voice vlan, you only need to “tag” that vlan as “voice” by literally using that singular command “voice” in the vlan configuration context. Doing so tells the switch that vlan is for voice use, and as such, the phone will use LLDP to first talk to the switch and tell it its a phone, and the switch will direct the phone to tag its voice traffic as that vlan. Easy peasy, and kinda cool!
On the port side of things, there’s a couple ways the port can be configured; if you’re not using LLDP, you can always set the port to be untagged as your voip vlan. The other way is to have the port set to your data vlan by default (native untagged), then add vlan 2 tagged to it. You do this by using the following commands (in the interface configuration context):
vlan trunk native 1 vlan trunk allowed 10
The above example assumes your data vlan is 1 and your voice vlan is 10. If you plug a computer into this port, it’ll get vlan 1. If you plug an ip phone into it, it’ll get vlan 10. Sweet!
So..an interesting issue I ran into was that while all this works great, the PC port on the phone did not work. With a laptop plugged in, it wouldn’t get an address from DHCP at all; if anything the typical jaded IT admin would assume it would get DHCP from the phone vlan since the phone is on vlan 10, however it went nowhere.
As usual I spent a couple HOURS searching on this issue with little success, until I tried some different search terms and found this article:
https://community.arubanetworks.com/community-home/digestviewer/viewthread?MID=239425
While the article above is using Cisco phones and a different issue, one little thing stood out; the vlan trunk allowed command I provided above ONLY has vlan 10 in it! The article shows an example using a command vlan trunk allowed 1,10.
AH HAH (I say that a lot) – This makes a lot of sense now. Natively, the port will provide access to vlan 1 as untagged, but only native, not with another switch attached! The ip phone is acting like a switch, hence why the command is “vlan trunk allowed 1,10″ – you’re telling it what vlans the TRUNK would have access to, not native! As such, yes you have to include the data vlan if you want other ports on that child switch (the pc port on the ip phone) to access!
So finally, using vlan trunk allowed 1,10 on the appropriate port did enable the PC port on the phone to talk to vlan 1.
ALSO – REMEMBER to save your config! write-mem
Hopefully this article helps you out – if so leave me a comment below!