Separate voice and data traffic to different WAN circuits

Posted on 2014-08-01
Last Modified: 2015-04-07
I'm trying to setup a scenario where all of the data traffic would use ISP A, and all of the voice traffic would use ISP B.  I've created a diagram on how I think the LAN should be reconfigured to make this happen, but I'm not sure if this is the best approach and the correct method to configure it.  I'm looking at policy-based routing vs. static routing.

In the diagram the Cisco 2801 router is not in production.  The current setup is that all traffic is going out ISP A for voice and data traffic. The configuration is a router-on-a-stick config with the Cisco 1921 being the gateway for all of the vlans.

Based on the attached diagram and router config what suggestions can be made to properly route the voice and data traffic out separate ISPs?
Question by:jplagens
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LVL 17

Expert Comment

ID: 40235722
Seeing the current setup, it might be the easiest change to move the VoIP IP from the 1921 to the 2801, that way using its default gateway to ISP B for the voice traffic.
Other solutions would be e.g. policy routing based on the source IP, or moving the voice interface into a new VRF with a separate routing table ...
LVL 45

Expert Comment

by:Craig Beck
ID: 40236177
Garry is suggesting exactly what I'd have suggested.  The VoIP traffic might as well use the 2901 if you can do that.  I know you said the 2901 isn't in production but if you can use it, I would.  You might want to think about configuring the IOS firewall on it too if it's licensed for it.

Otherwise, PBR is the way to go at the 1921.  Again, you'd want to use the IOS firewall to protect the link from ISP-B.

Author Comment

ID: 40241227
I tried this last week, but we had to reschedule.  The 2801 was having issues and ISP A was having some different problems.  As it turns out, we won't be able to use the 2801.  ISP B is using a Cisco IAD router and can provide a managed firewall with their voice solution.  I updated the diagram to reflect the topology and the subnets involved.

I like the idea of moving the voice gateway.  In doing that would I remove the voice subinterface and voice dhcp pool  from the 1921 router and then have ISP B change their inside interface to (current voice gateway) and provide dhcp for their phones?  ISP B is providing a hosted pbx for their voip solution.
LVL 17

Accepted Solution

Garry-G earned 500 total points
ID: 40241664
Splitting up the traffic to different gateway will be the cleanest, simplest and most easy to understand solution.
Generally I'd recommend or prefer a solution that would allow for failover of one connection to the other in order to provide improved availability, but this would most likely require some level of cooperation from both ISPs and some decent planing as far as router config goes ...

Author Comment

ID: 40241791
Agreed.  The final goal of this is to send all data traffic out ISP A and voice traffic out of ISP B.  If either circuit goes down all of the traffic would reroute out the functioning circuit until the other service is restored.  Then the traffic would go back to normal.  The immediate need is to separate the traffic.

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