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Community Member

SG300-10 Auto Voice VLAN not working properly


At our office we use seven Cisco 300 Series Small Business Switches. One main switch in the server room and one in each room. They work great! But I’m having difficulties getting the Auto Voice VLAN to work correctly. In fact, it seems to works straight away on a PoE model, but not on the non-PoE models. Allow me to explain my scenario.

Switch (main server room):

  • Cisco SG 300-28 (PID:SRW2024-K9)-VSD

Switches (one in each room):

  • Cisco SG 300-10 (PID:SRW2008-K9)-VSD
  • Cisco SG 300-10 (PID:SRW2008-K9)-VSD
  • Cisco SG 300-10 (PID:SRW2008-K9)-VSD
  • Cisco SG 300-10 (PID:SRW2008-K9)-VSD
  • Cisco SG 300-10 (PID:SRW2008-K9)-VSD
  • Cisco SG 300-10P (PID:SRW2008P-K9)-VSD

All these switches use firmware v1.1.1.8. The switches in each room are connected to the central switch by Link Aggregation. The main switch is configured in Layer 3 mode and all the others in Layer 2 mode. We have a lot of VLAN’s configured. For this problem allow me to describe only the two that are relevant.

  • VLAN 102 - Internal Network (Clients)
  • VLAN 104 - Internal Network (Voice)

The switches on each room are mainly used for clients, printers and IP phones. The clients and printers should operate in VLAN 102. The IP phones should operate in VLAN 104. For this to work I have the 10 port switches configured as following.

  • GE1 – Trunk – 102U;104T
  • GE2 – Trunk – 102U;104T
  • GE3 – Trunk – 102U;104T
  • GE4 – Trunk – 102U;104T
  • GE5 – Trunk – 102U;104T
  • GE6 – Trunk – 102U;104T
  • GE7 – Trunk – 102U;104T
  • GE8 – Trunk – 102U;104T
  • GE9 – Trunk – 1P (LAG 1, with 1U;102T;104T)
  • GE10 – Trunk – 1P (LAG 1, with 1U;102T;104T)

The network is fully routable. A DHCP Server is available. Each VLAN uses DHCP relaying. If we statically assign a VLAN to a port, that just works fine. Auto Voice VLAN is enabled with VLAN ID 104. All switches are configured the same. But this is what occurs…

  • When I connect an IP phone on the SG300-10P the IP phones are assigned to the Voice VLAN ID 104. If I would connect a desktop to that same port it is assigned to VLAN ID 102. Exactly as it should.
  • But when I connect an IP phone on a SG300-10 the IP it is assigned to VLAN ID 102. But I also noticed that in some cases they are assigned to VLAN ID 1 and don’t get an IP Address. That depends in which order I change settings. The port its VLAN membership is then even changed to 1P. Although the port is recognized as an “IP Phone” by the smartport feature. I have noticed it does make difference if I modify the smartport macro and change the native_vlan paramater from "1" to "let's" say "102". That seems to affect it.

Of course it may be just coincidence. What am I doing wrong? How should it work?

How should you actually configure each port on a switch? (trunk?, Tagged/Untagged VLAN?)

If you do not use Telephony OUI. Do you still need to configure the macros on the smartport defenitions?

I have tried about everything. I have also tried Telephony OUI, but it doesn't make any difference. I just can't get it to work properly on the non-PoE switch. I hope you can advice me. We have all kind of IP Phnones, most of them are from Polycom.

Community Member

Re: SG300-10 Auto Voice VLAN not working properly

Yesterday I have tried a lot of things. At a certain moment I have configured another value for $native_vlan in the smartport macros. Suddenly it seemed to work for some switches. But strange enough not all of them. They are configured the same. I have checked over and over again.

I am quit confused right now. Is it required to edit the smartport values or can you leave with default values?


Re: SG300-10 Auto Voice VLAN not working properly


Please call into Cisco Small Business Support Center @ 1-866-606-1866 and open a support ticket for trouble shooting as this will be difficult via support community.



Community Member

Re: SG300-10 Auto Voice VLAN not working properly


I haven't called Cisco Small Business Support Center. But I want to let you know I have solved the problem.

Although all switches are configured the same, where set to factory default once before and updated to firmware v1.1.1.8; but apparently on some switches the LLDP MED Port Settings where not configured at all. On each port the LLDP MED Status was not enabled and at the selected optional TLVs "Network Policy" was not selected.

To be exactly this is what I did...

  • Go to Administration > Discovery - LLDP > LLDP MED Port Settings
  • Select a port (e.g. GE1) and click Edit
  • Enable LLDP MED Status
  • At Selected Oprtional TLVs select Network Policy and click Apply
  • Then do the same for each desired port, or copy the settings to other ports.

The only weird thing about this is. I have "never" touched the LLDP settings before. These switches are bought at the same time. I do not understand why some have it already configured. Another thing I noticed. On these switches that didn't work before, when I went to Administration > Discovery - LLDP > Port Settings, I noticed that the settings are not shown. After two refreshes they are finally shown. It might be detail, but it gives me a bad feeling.

I consider this post as solved/answered.

What I am going to do myself; reset all these switches to factory defaults and re-configure them. Only then I can be 100% sure each switch is configured the same. If I notice a difference after factory default, I will let you know.


Community Member

Re: SG300-10 Auto Voice VLAN not working properly

How to configure Voice Vlan on Cisco Small Business 300 switch?

When I made Trunk port and attached there voice and data vlans the phone did not work, it wrote configure IP and no more. But when I attached cable into my laptop data vlan worked properly, with phone did not. Could you help me to resolve this problem?

Thanks in advance


Re: SG300-10 Auto Voice VLAN not working properly

Hello David, the auto voice vlan works off of CDP and LLDP advertisements. Dependings on the advertisements of your devices, the auto smartports will configure the connection between the units. The auto voice vlan is as simple as specifying what vlan is for the phone.

Your phone must support CDP or LLDP-MED for these features to work.

To configure the auto voice vlan is a matter of creating the desired vlan id then going to the voice vlan section of the switch and identifying what vlan is your voice vlan.

If you plan using LLDP-MED, look at the pictures on those post-

Please rate helpful posts

-Tom Please mark answered for helpful posts

Re: SG300-10 Auto Voice VLAN not working properly

Hi david

Why not open up your own message.  Everyone in this tread will get your query.

But we need more information there are too many unanswered questions in your query.

I would beg you for a topology diagram , even a simple microsoft paint picture,  showing the network topology is worth a thousand words would be most useful..

  1. How is the switch connecting into the call control (VOIP) phone system ?
  2. is the Call control box vlan aware or does it have to sit on a untagged vlan port?
  3. Are the phones VLAN aware and can they use LLDP or CDP to learn what VLANs they have to connect to?
  4. Is the WAN router VLAN aware and what VLANs need to be propogated to the switch?

If you have trouble answering these questions, find someone , a friend/colleague that can help.

regards Dave

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