Configuring a SRW208P with VLAN and QoS for VoIP prioritization

Unanswered Question
Mar 16th, 2010


I’m trying to configure a Linksys  SRW208P with VLAN and QoS to prioritize VoIP traffic.  I need a little  (a lot, really) of help with the strategy and setup. 

The  elements:
To the SRW208P switch we will connect 4x Cisco 7940G phones  and the computers connect to the phones pass-through port.

Our  PBX is a virtually hosted asterisk server.

As a router we are  using a Netopia 3000 that supports VLAN but I don’t see any  configuration for QoS.

Here is the current idea:

In the  switch we will create the VLAN’S
VLAN 1: Management/Admin (if its  necessary?)
VLAN 20: Data

The Cisco Phones  will be connected to port 1-4

QoS in the switch will be setup to  give VoIP Traffic the highest priority always.

Is this about  right? And how should I configure the SRW208P to achieve this.

-  Larry Tous

I have this problem too.
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alissitz Wed, 03/17/2010 - 06:32


There are many tutorials on our PEC or even on youtube.  You might choose to check these out since they are free to partners / the world.

The 7940 does not support 802.3af, and only Cisco's proprietary POE.  Will you have power supplies with these phones?

If you still want these older phones, you can try the ESW series switches as these support CDP and will negotiate the poe to the phones. The ESWs also have many defaults which accommodate voip and also smart ports.

You can use multiple vlans if you like, and then you will need to configure the swtich to trust COS (should be default) and to provide prioritization based on COS.  This should also be default.

Do you already have a router picked out that supports multiple VLANs?

In case you wanted to keep all devices on the same vlan, you can also configure 'Advanced QoS' on the switch and have the switch trust DSCP.  The packets will be marked accordingly and voip will receive better priority.

In this case, you will be fine under most conditions, but a DOS attack / virus will cause many problems for all devices since they are on the same vlan.  One of the nice things about keeping the phones on their own vlan is security (and QoS) ...


Andrew Lissitz


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