Frame Relay Traffic Shaping Question

[timm.benkula]

If your CIR matches your port speed do you still need to use FRTS? I'm converting our remote sites connections to our providers MPLS network using Frame relay circuits at full port speed. Some are 256K, some are 512k and a few are full T-1's.

[scottmac]

As is the case for many things that are IT related ..." It depends."

From a site with CIR @ port speed talking to another site of the same or greater port speed, no ... because you cannot exceed port speed.

From a site with a Full T1 bandwidth (and CIR@port speed) sending to a site that is fractional T1, then yes .. because the T1 site is sending full speed to a site with less bandwidth and you'll seriously congest ... or at the least, increase your latency considerably because of buffer time (or packets will eventually be expired and dropped if it's a fairly constant stream of traffic).

Bring up traffic shaping anywhere that has CIR < port speed, and / or is talking to another site with less bandwidth.

Good Luck

Scott

[timm.benkula]

Any site can talk to any other site via the provider's MPLS network. So each of my CE routers is talking to the provider's PE routers via one PVC. I'm assuming that the provider's network will handle the buffering when a higher speed connection is talking to a lower speed connection. Otherwise, I'm not sure how I could control the bandwidth based on the destination.

[scottmac]

I forgot about that MPLS thing you mentioned .... quite a wrinkle there.

I believe your best first option would be to talk to your provider. Generally speaking, the networks of the cloud are designed to move the traffic as fast & efficiently as possible ..... no serious buffering.

MPLS give them some traffic engineering options (path selection), and provide some QOS options ... but in order to do anything related to traffic shaping, it would probably require reprovisioning the label for that path (if at all possible).

It might boil down to doing some clever queuing or traffic manipulation by policy at the interface / subinterface.

I have some folks I can talk to at work ... I'll check with them and see if they have any helpful input.

Good Luck

Scott

[Erick Bergquist]

I would recommend configuring FRTS on the routers, without it then the traffic gets sent at port speed as fast as router can send it out. With FRTS configured, the router will send the traffic at a steady flow per FRTS parameters specified so it will be more controlled when it leaves you're network. FRTS setings per PVC should match on both sides.

If you're doing VoIP you want to do FRTS to get the traffic interval down to 10ms or 20ms (whatever your codec sampling rate is) so it gets out in timely manner. Default interval is 120ms. You'll also want to look into QoS/LLQ perhaps.