callmanager QOS

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Jun 14th, 2007
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Are the packets leaving the callmanager tagged QOS packets? IE can i trust the port on the switch that the callmanager is connected to?

Also is an H323 gateway (registered in CM) automatically tagging packets with QOS, again can i trust the gateways switchport?


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thisisshanky Thu, 06/14/2007 - 14:39
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Yes the answer to both questions is packets are marked. So you can trust the ports. For H323 gateways, the default packet tag for control signalling is af31. you will need to change this cs3 using command.

ip qos dscp signalling cs3 under dial-peer.

i would recommend that you remark these at the switch to the appropriate dscp/cos etc for the reason that if callmanager gets compromised and packet tags are altered, your network will still remark packets to defaults.

shaun.white Thu, 06/14/2007 - 16:41
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So i would set that under my VOIP dial peer thats destination is the callmanager ip right? i dont put it under my pots peers...

and for the remark on the switch, i would want to write an ACL that captures packets from the h323 gateway to the CM on the H323 ports and RTP ports right? theres nothing else im missing?

thanks again!

Steven Holl Tue, 06/19/2007 - 13:43
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All Cisco voice products will mark RTP packets with a DSCP value of EF, and control packets with AF31. This includes all gateways, minus a 6608 which only can mark a CoS and relies on the Cat to map the CoS to a DSCP value. Recent CallManager versions mark control traffic with CS3, though.


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