VOIP config for 1841

[paulwoodsy]

Hi,

One of our clients have plans to use VOIP. Since we only manage their 1841 routers I've been issued the following parameters-

DIFFSERV/TOS PARAMETERS                  RTCP Reporting  Enabled? y

Call Control PHB Value: 46      RTCP MONITOR SERVER  PARAMETERS

Audio PHB Value: 46       Use Default Server  Parameters? y

Video PHB Value: 26

802.1P/Q PARAMETERS

Call Control 802.1p Priority: 6

Audio 802.1p Priority: 6

Video 802.1p Priority: 5

Since I'm new relatively new to Qos, could you shed some light on how best to turn this into meaningful config fit for an 1841 router? Will Auto Qos lessen & simplify this type of configuration?

Much appreciated.

[cadet alain]

Hi,

AutoQoS will indeed simplify things but to get it working you need to issue correct bandwidth command on WAN interfaces.

Who gave you these params? PHB of 46 is EF is for voice bearer not for voice control and the same goes for CoS( 802.1p priority) and furthermore it is highly discouraged to use CoS 6 and 7.

Regards.

Alain.

[paulwoodsy]

Thanks for your response Alan.

I've recommended they adopt the preferred IP precedence 5 marking & look at validating the call control parameters.

If I turn on "auto qos voip trust" on my MPLS interface I guess this will then load the neccessary config on the 1841 by copying the Qos settings from the LAN.

My bandwidth commands I'm going to look at deploying are:-

policy-map EGRESS_MARKING
class VOICE_TRAFFIC
bandwidth percent 50

Seems I've covered everything now or am I missing any of the other parameters?

[sean_evershed]

It is recommended that voice traffic to be assigned to the low latency queue.

Therefore you should use the command  priority percent 50 rather than bandwidth percent 50 in the class VOICE_TRAFFIC.

Please rememeber to rate all posts that are helpful.

[paulwoodsy]

Thanks Sean.

I've now amended accordingly.

LLQ is better suited for my voice traffic thanks to the strict priority queues. Thanks for pointing this out.