Digium IP D40 Phones - Cisco Voice VLAN-ing

Posted on 2016-08-27
Medium Priority
Last Modified: 2016-09-04
Hello All,

I have 3 Cisco 3850's LAN Based Software (POE+) switches. I am not 100% familiar with Cisco products, more like 40% familiar and have been managing this network for several years with great success. We recently, for the first time, purchased a VoIP system and I need to get the phones set up. I have put the Digium Phone System on VLAN-55 (Phone System) and the phones (all of them) support CDP and LLDP on them. On the "Small Business Switches" (ex: SG500/SG300, etc.) they have what is called a "Voice-VLAN" where when the switch see's the first 6 octets of a mac-address it auto adds it to VLANX (ex: VLAN-55). On my Cisco 3850 however, it does not (obviously) because it's a full blown OS vs the stripped down version on the SG models.

So instead of me walking around and configuring roughly 60+ phones, is there a way to configure the Cisco 3850 POE+ switches (which phones will be plugged directly in through out the office) to program it and know that when it see's the first six octets of this mac-address to auto add it to this VLAN (ex: VLAN-55)?
Question by:JustinBMak
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LVL 43

Expert Comment

ID: 41773800
Try this.

Interface range g1/0/1-48
Switchport voice vlan 55

The interface range allows you to specify multiple interfaces all at once, instead of doing each one individually.

The voice VLAN command tells the switch to tell the phones to use vlan 55. I have used is successfully with Avaya and ShoreTel phones. The switch communicates with the phones via LLDP to set the VLAN.

Author Comment

ID: 41774056
Hi Kevinhsieh:

Quick question, since "technically" the "voice-vlan" feature is not an option on the Cisco 3850's like how it is on the Cisco SG Models. Is there a way to configure the "Voice-VLAN" feather on the 3850's? I have not configured the option above (it's the weekend and the switch is not in production yet). But I thought I would just ask while I was thinking about it.

Here is a link to a video on the Voice-VLAN on the SG models:
LVL 43

Accepted Solution

kevinhsieh earned 2000 total points
ID: 41774168
The 3850 does so much more than the SG series. So, I am not sure what you mean by there not being a voice vlan feature on the 3850. One thing I noticed is that the SG series had the ports in trunk mode. On the 3850, they should be configured as access ports.

I believe the switch will by default access CoS and DSCP QoS tags generated by the phones. They are not actually important on a LAN. It's only important when going over a WAN link that may experience congestion. Your switch should support AutoQoS. It's a feature I haven't used before, but it is available. http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/auto_qos.html

Here is all the configuration you need. Is puts regular devices on VLAN 10, and phones on VLAN 55. It works if you plug PCs/printers into the phone, and then plug the phone into the switch. If your equipment is on VLAN 1 instead of 10, it will not appear in the configuration because that's the default setting.

interface GigabitEthernet1/0/48
 switchport access vlan 10
 switchport mode access
 switchport voice vlan 55
 spanning-tree portfast

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Author Comment

ID: 41774192
Thank you sir. I'm sure I'm making it more complicated than what it really is, I will be working on this tomorrow and will let you and future EE people know how it goes.

Author Comment

ID: 41777464
Hello Again,

So the above did not work, all my phones got an IP from the "data network" (VLAN-15). I have the above config in as you instructed and double checked the phones to make sure LLDP is turned on, which it is.

So, is there additional config I'm missing?
LVL 43

Expert Comment

ID: 41777491
Well, my Avaya phones use the voice VLAN setting from the switch. I think my Shoretel phones get the vlan from a DHCP attribute.  What does the phone documentation say?

Author Closing Comment

ID: 41784084
Thanks for the reminder EE

So kevinhsieh was correct, the issue why it wasn't working originally (and it was my fault) was due to the fact I guess I forgot I enabled lldp (which I swore I did).

Once I enabled LLDP (Link Layer Discovery Protocol), the phones auto picked up an IP on VLAN55 (Voice Vlan) and auto configured them selves as they should (as long as the port is trunked correctly).

This forum here also assisted and reminded me to enable LLDP, which again I thought was enabled. I'm only posting this link to help with QOS (if needed):


Thanks again kevinhsieh.

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