VOIP with Frame Relay

[mdoyle]

Hi,

I have a 512K frame relay link with a 256K CIR. I'm setting up QOS and FRTS, and using a LLQ for VOIP. Why is it recommended to disable adaptive shaping? What effect does it have when it is disabled, how does the router handle going between the CIR and access link speed and allow for frame congestion?

thanks.

[a-vazquez]

Check for such details in the document :

Adaptive Frame Relay Traffic Shaping for Interface Congestion

http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a0080087b91.html

[mdoyle]

Thanks for trying but it doesn't answer why you disable adaptive shaping when using LLQ. It only covers frame traffic shaping and not L3 QOS

[dgahm]

The Cisco recommendation is that you set the traffic shaping so that you never exceed your CIR when using a frame circuit for VOIP. In that scenario adaptive shaping is not needed since you should never see a FECN or BECN. Good quality voice cannot be maintained if packets are being discarded, and frame networks do not honor tags so you can't guarantee that data packets will be thrown away before voice. This of course negates much of the attraction for frame relay, but is the reality.

We converted some of our frame circuits to frac-T1, and are successfully allowing burst to port speed on those where our carrier never throws away packets. This is probably unique in that our carrier has lots of excess bandwidth, and most circuits only traverse one frame switch. When in doubt, don't burst.