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[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles

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[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles

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[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
2022-09-22 22:15:06 - last edited 2022-09-24 02:33:56
Tags: #VLAN & Multi-Networks #VoIP
Model: T1600G-52PS(TL-SG2452P)  
Hardware Version: V4
Firmware Version: 4.0.6 Build 20200918 Rel.57276

Greetings!


Please consider these conditions before continuing to read:

 

  • I don't do network architecture enough to grasp all the terminology
  • The equipment is 900 miles away from me and the customer isn't technical enough to make adjustments
  • I am able to configure the switch remotely through the web interface
  • I do have the MAC addresses and IP addresses for most devices on the networks
  • The subnet addressing and gateways are not under my control and I cannot make changes to them

 

Network Description

My customer has two independent gateways to the internet: voice and data.  The data gateway is 192.168.58.1 with the subnet being 192.168.58.0/24 and is connected to the TP-Link switch at port 47.  The voice gateway is 10.30.30.254 with subnet of 10.30.30.0/24 and connected to the switch at port 48.  There are about 15 VoIP Polycom phones connected to the TP-Link switch at various ports.  These Polycom phones each have a one-port Ethernet switch where one PC can be connected.  Most of the PCs at the customer's office are connected through the phones in this way, with the phones connecting to the TP-Link switch.  The VoIP vendor has indicated that these Polycom phones have been each programmed to use VLAN 300, although their behavior doesn't support this.
 

Here is a (badly drawn) picture of the topology:

 

 

As of now, all of the data AND voice are using the data gateway because I am unable to get the TP-Link T1600G-52PS to route voice traffic to the voice gateway.  This is causing congestion and also they are running out of IP addresses on the data subnet.  The VoIP phones are getting their IP addresses from the data gateway when they should be getting their addresses from the voice gateway.  I want all data traffic to be on VLAN 1 and want voice traffic to be on VLAN 300.

 

I have configured the port going to the voice gateway (port 48) with VLAN 300 'tagged' enabled while ports that are connected to the VoIP phones 'untagged' enabled.

 

What I've Tried

(When I say "This does not work" below, it means that the Polycom phones will not use the voice gateway's DHCP server, nor will VLAN 300 traffic go to the voice gateway)

 

* I have tried setting static routes between the TP-Link switch, data and voice subnets, and this does not work.

 

* Pinging the voice gateway from the TP-Link switch does not work.  I then tried making port 48 a routing port, then I am able to ping the voice gateway, but cannot enable 'tagged' on that port for VLAN 300.  The phones will not use the voice gateway's DHCP server.

 

* I have tried LLDP and LLDP-MED to coax the phones to get their addresses from the voice gateway.  This does not work.

 

* I have tried to use all of the different DHCP relaying features, and this does not work.

 

* I have used MAC-address-VLAN assignment to the phones, which does appear to force them onto VLAN 300, but they will not even try to get an address from either the data or voice gateways.

 

Again, I am not an expert on advanced network architecture, so what might be obvious to you is not to me.  I typically do "simple" unmanaged network layouts, Windows / Mac / Linux tech support and software development.

 

What can I do to: 1) Force the Polycom phones to get their IP addresses from the voice gateway instead of the data gateway?  2) Force VLAN 300 traffic to only flow from 'untagged'-enabled ports through port 48 to the voice gateway?

 

Thank you in advance!

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#1
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1 Accepted Solution
Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles-Solution
2022-09-23 19:09:56 - last edited 2022-09-24 02:33:56

  @ScrotTailNern 

 

Is that Voice Gateway VLAN-aware or not? If not, try changing Port 48 in VLAN 300 to Untagged and set PVID to 300. You can remove this port from VLAN 1, too.

Kris K
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#4
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Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
2022-09-23 05:42:11

  @ScrotTailNern 

Is there any details about your VLAN settings? I think the Phone and the Voice gateway should be able to detect the tagged data. You may contact your phone support and ask how to let it detect VLAN tagged data.

Let us take port 1, 47, 48 as an example.

So you will need to have VLAN1 and VLAN300. 

On VLAN1 it has port 1,47 and both of them are untag, PVID 1;

On VLAN300 it has port 1,48 and both of them are tagged.

 

The auto VoIP setting is used to put voice data in higher priority. If the VLAN does not work porperly, I don't think LLDP or related settings can work.

 

Here is an article from tplink, you may refer to the Auto VoIP part.

 

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#2
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Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
2022-09-23 16:25:33

Somnus wrote

  @ScrotTailNern 

Is there any details about your VLAN settings? I think the Phone and the Voice gateway should be able to detect the tagged data. You may contact your phone support and ask how to let it detect VLAN tagged data.

Let us take port 1, 47, 48 as an example.

So you will need to have VLAN1 and VLAN300. 

On VLAN1 it has port 1,47 and both of them are untag, PVID 1;

On VLAN300 it has port 1,48 and both of them are tagged.

 

The auto VoIP setting is used to put voice data in higher priority. If the VLAN does not work porperly, I don't think LLDP or related settings can work.

 

Here is an article from tplink, you may refer to the Auto VoIP part.

 

  @Somnus Thank you for the reply.

 

Yes, the ports are untagged and tagged as you specified.

 

I also tried the Auto VoIP and Voice QoS features, but the Voice QoS really is of little value to me because it will either degrade the voice quality or further degrade the data traffic quality.  I will experiment with the Auto VoIP feature again after-hours as I can't experiment while the customer is working.

 

As far as contacting the VoIP vendor -- they have pretty much just dropped everything in my lap and I'm basically on my own.  Not the best support, but I didn't choose them. frown  I'm starting to think these phones were not programmed correctly in regards to VLAN 300.

 

Thanks again! smiley

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#3
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Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles-Solution
2022-09-23 19:09:56 - last edited 2022-09-24 02:33:56

  @ScrotTailNern 

 

Is that Voice Gateway VLAN-aware or not? If not, try changing Port 48 in VLAN 300 to Untagged and set PVID to 300. You can remove this port from VLAN 1, too.

Kris K
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#4
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Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
2022-09-23 19:29:08

  @KJK Thank you.

 

KJK wrote

  @ScrotTailNern 

 

Is that Voice Gateway VLAN-aware or not? If not, try changing Port 48 in VLAN 300 to Untagged and set PVID to 300. You can remove this port from VLAN 1, too.

 

I believe the voice gateway is vlan-aware.  While I am restricted from making changes to it, I have seen its configuration page and I clearly remember that VLAN 300 was set up within it.

 

I have tried what you suggested without success.  Trust me, if there is some permutation I haven't tried, I'd be surprised.

 

What is irritating is that so many other devices were connected to this voice gateway before I disabled untagged VLAN 1 on port 48.  If all of those iPhones and tablets could accidentally find their way to this subnet, I wonder why these silly phones, designed to be used with a voice-aware gateway cannot...?  Just asking into the air, for the most part...

 

Can you please define "PVID" in this context?

 

Thank you! :-)

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#5
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Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
2022-09-23 20:55:05

  @ScrotTailNern 

 

PVID (Port VLAN ID) is a value set for a port that is a member of a VLAN. The default value of PVID is 1 because of the default VLAN 1. In this particular case, setting it to 300 (VID of VLAN 300) should help if you deal with a VLAN-unaware gateway. That will tell the switch to which VLAN frames coming from the gateway belong to.

 

If the gateway is VLAN-aware, it is necessary to learn the VLAN configuration of the port in the gateway that the switch is connected to and mirror this configuration on the switch side.

 

Kris K
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#6
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Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
2022-09-23 21:56:23 - last edited 2022-09-23 21:58:00

  @KJK Thank you for the information.  I think I knew some of this already, just in different terminology.

 

If it helps, here are two screenshots from the voice gateway:

 

 

 

Here is a screenshot of the TP-Link switch VLAN 300 configuration (port 17 is one Polycom phone with a Windows PC connected to it, only testing with one phone at a time):

 

 

 

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#7
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Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
2022-09-24 01:19:00

  @ScrotTailNern 

 

It looks like that Voice Gateway is VMware. I have no experience with it so I’m not sure if I understand its screenshots correctly.

 

Anyway, Interface LAN2 has VLANs 1 and 300. VLAN 300 is Untagged so that implies PVID of 300 and VLAN 1 Tagged. To match this on the switch side, you should mark Port 48 Untagged in VLAN 300 and set its PVID to 300. You can add Port 48 as Tagged to VLAN 1 as well for a closer match. I think PVIDs can be configured at VLAN > 802.1Q VLAN > Port Config in this switch.

 

I guess Port 17 is where a phone is connected so it should stay Tagged in VLAN 300 and Untagged in VLAN 1.

 

Also, it would be a good idea to check if the phones are really configured with VLAN ID 300 either through their menu or analyzing their traffic with Wireshark.

Kris K
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#8
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Re:[T1600G-52PS] VLAN, VoIP, DHCP and routing troubles
2022-09-24 02:32:48

Thank you everyone for your help!  :-)  I think I have it now.  Tonight I was able to get my test phone to go over to VLAN 300 and the attached PC stayed on VLAN 1.  Here are the things that seem to matter:

  • The PVID of port 48 (connected to voice gateway) needs to be 300
  • Port 48 needs to be untagged VLAN 300
  • Ports going to phones need to be untagged VLAN 1 and untagged VLAN 300
  • The MAC addresses of the phones need to be entered into the VLAN - MAC table and the phone port selected for VLAN - MAC

 

These things didn't help:

  • DHCP relaying
  • LLDP and/or LLDP-MED

 

What I might try later, after bringing over one phone at a time to VLAN 300:

  • Voice VLAN
  • Auto VoIP

 

I'm sure each of you gave me pieces of what I need, so I am very grateful!  Thank you so much! smiley

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Views: 1280

Replies: 8

Tags

VLAN & Multi-Networks
VoIP
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