Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Frame Relay Utilizing CEF

I am looking at deploying an nxT1 Frame Relay solution utilizing CEF, instead of utilizing an IMUX. Has anyone ever come across a scenerio like this before? What are the inherent problems with going this route?

We have some concern about the delivery of the packets being out of order if per destination load balancing is selected. Does CEF (on a per destination level) operate by looking at the host portion of the packet? What happens if there is only a single centralized host at the hub location. Will only one link be used if per destination is enabled. Or does per destination operate on a session by session basis, even if the destination is the same?


Re: Frame Relay Utilizing CEF

CEF per destination works on source/destination combo.

For example, traffic from source A going to destination C will go over one PVC and traffic from source B to destination C will go over the other PVC.

If you're using per-packet then thats when out of order packets can cause problems.

New Member

Re: Frame Relay Utilizing CEF

If you want true load sharing, you should use per-packet. Although it puts a greater strain on the router and packets being delivered out of order could happen, there is a chance of the majority of traffic using only one PVC if you rely on per-destination. As the CEF table builds, per-destination will send all traffic destined for the same destination address down the same PVC every time.