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New Member

VOIP QoS Over Serial

I have two 3845's on a table, each with a Gigabit port connected to a switch. There is also a DSU/CSU card in each connected via a crossover cable on a different subnet.

E/M port on transmit router has a constant audio source, E/M port on Receive router hooked up to a speaker system.

Transmit Router:

voice-port 0/0/0

type 5

signal lmr

no vad

timeouts call-disconnect 3

connection trunk 500


dial-peer voice 500 voip

destination-pattern 5..

session target ipv4:

codec g711ulaw

Receive Router:

voice-port 0/0/0

type 5

signal lmr

no vad

timeouts call-disconnect 3

dial-peer voice 500 pots

destination-pattern 500

port 0/0/0

With this setting the trunk is setup and the audio goes across with a dscp of EF and everything works.

If I change the session target to go across the PPP link and shu/noshut the voiceport I get audio for about 9 seconds and then it quits. And the DSAP for thos 9 seconds is not set.

access-list 120 permit ip any any dscp ef

via debug ip packet 120 shows nothing.

Any ideas?


Re: VOIP QoS Over Serial

New Member

Re: VOIP QoS Over Serial

Try making your configuration mark with a inbound and out bound tagging. It sounds like you only have one way QoS.

class-map Inbound

match all dscp 46

class-map Outbound

macth all dscp 46

policy-map Voice Inbound

class Inbound

policy-map Voice Outbound

class Outbound

Apply both policy maps to the interfaces that allow communication between the routers.

I did not include priority settings or bandwidth precentages in this configuration.

This will allow tagging both directions.