QoS for IP2IP gateway to call manager

Unanswered Question
Apr 28th, 2009

We have two SIP trunks, one for Main site and a shadow for our DR site.

When the main site goes down, the call path from outside in is to DR IP2IP Gateway router, to a 3750 router, across a DS3 Point to Point circuit, to a 7206 router, then to our Call Manager server.

The QoS policy would be on the 3725 router to the 7206 router that connects the DS3 Point to Point.

When there is heave traffic on the DS3, the call quality suffers when the Main Site SIP trunk is failed over to DR.

If I wanted to set up a QoS policy for the traffic inbound from IP2IP Gateway (CUBE) to call manager, how would I mark the traffic?

Also, would I also need a policy in the direction of Call Manager to IP2IP gateway for the connection in that direction?

I have this problem too.
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chadlincoln Wed, 04/29/2009 - 05:30

In terms of marking the traffic, voice gets marked to dscp ef and signaling gets marked to cs3 or af31. Your class maps would look like this:

class-map voice

match ip dscp ef

class-map match-any signaling

match ip dscp af31

match ip dscp cs3

Then under your policy-map, best practices would be:

policy-map WAN-EDGE

class voice

priority 33

class signaling

bandwidth 5

class class-default

fair-queue

If you're only wanting to mark the traffic and not enforce any rate limit, put this:

policy-map WAN-EDGE

class voice

set ip dscp ef

class signaling

set ip dscp cs3

class class-default

set ip dscp default

Not sure if this is what you were looking for. Please rate if this helped. Thanks.

wilson_1234_2 Wed, 04/29/2009 - 06:53

Thanks for the input.

I didn't know if the traffic from IP2IP Gateway router would be marked the same as from Call Manager to the phones.

Also, is the policy both ways?

chadlincoln Wed, 04/29/2009 - 08:39

What type of connection do you have across the WAN?

MPLS:

I'd make sure I'm matching the markings the carrier is looking for before I send them across. In that case I would mark outbound on the serial interface across the WAN.

Point to point:

I'd still mark on the outbound, but check and see if they're keeping the markings across the WAN. If not, you may have to remark on the outbound of the ethernet handoff back into the LAN.

Please rate if this helps. Also let me know if you have any problems.

Nicholas Matthews Thu, 04/30/2009 - 09:52

I posted a pretty long discussion on how to mark and classify traffic for voice in another thread. This might be a good read:

http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Unified%20Communications%20and%20Video&topic=Video%20over%20IP&topicID=.ee6c82f&fromOutline=&CommCmd=MB%3Fcmd%3Ddisplay_location%26location%3D.2cd2428f

Basically - you may not want to assume that incoming traffic from your SIP provider has the correct marking of EF for voice and cs3/af31 for signaling. You may want to match on ACLs so that you know for sure.

As well, you will want to tailor your QoS policy for the type of link you have. If your DS3 is only doing voice traffic, you'll want to give it a higher percentage than 33 for voice. This calculator should be helpful for determining the values to put into your service policy:

http://tools.cisco.com/Support/VBC/do/CodecCalc1.do

For CUBE you'll be concerned with SIP/H323 traffic, and whatever the RTP range your SIP provider is utilizing.

hth,

nick

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