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New Member

Matching Voice traffic


We have to match and prioties voice traffic on our WAN routers (887,1921,2921 and 3900 series).I have seen diffrent way to match Voice traffic as follow,

What is the best practice to match VOIP traffic on WAN routers and sent to MPLS provider.


access-list 102 permit udp any any range 16384 32767

access-list 102 permit tcp any any eq 1720

class-map match-any VoIP
match access-group 102

policy-map VOIPQOS

class VoIP

priority percent 50


class-map match-any VOIP

match  dscp ef

match ip precedence 5

policy-map MPLS-Link

class VOIP

  priority 10000

  set dscp af31

class class-default

Hall of Fame Super Bronze

Matching Voice traffic

It's best to tag at ingress (access switch) thus going with option 2 is often the implementation done at the WAN routers.

New Member

Matching Voice traffic


But Does option 2 will work on all routes eg:Cisco 887 ?


Super Bronze

Matching Voice traffic


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Believe it should, but not 100% sure.  Features do vary by platform, IOS version and feature set.

BTW, option 2 overlaps, i.e. IP Prec 5 includes IP DSCP EF.  What would be unique is DSCP CS5 and DSCP EF.

Matching Voice traffic


I would strongly recommend the option 2.

The router needs to spend less (CPU) resourses to check the ToS value of the packet than to perform a match according to a definition of the access-list entries.

If  the router can not receive the traffic already marked by the other devices (e.g. IP phones etc) then you have to use the option 1. The option one has also the drawback of the high UDP port range for mathcing.

This is usually the method  that we select between one of the two options.

Hope that helps,


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