MLPP Bandwidth Statements

[kbehrens]

HI - I was wondering if there are any advantages or disadvantages to hardcoding the bandwidth statement on a MLPP interface versus letting it be set dynamically by the router.

Thanks, Karen

[gatlin007 · Accepted solution]

One thing that comes to mind is service policies.  If there is a service policy attached to the MLPPP interface, then the policy evaluates the interface bandwidth value when it allocates bandwidth per class based on a percentage. 

Let's say there were three T1's in a bundle and a particular class was allocated 20%.  This would be about 900Kbps normally.  If one T1 drops out due to a circuit outage than the interface bandwidth value would automatically change to 3Mbps; in turn automatically shrinking the bandwidth available for the class to 600Kbps.

Manually setting the bandwidth attribute on the MLPPP interface would prevent this automagic from occurring.

Chris

[kbehrens]

Thanks for the response - that makes sense.  I have another question that perhaps you can answer - I have a six T1 MLPPP bundle in a 3845, T1s on S0/0/0 - S0/3/0 and S1/0/0-S1/1/0.  I'm having circuit issues on S0/0/0 and it took down the entire MLPPP.  I admin downed the interface and the MLPPP came back up.  I then had issues on S1/0/0 and again, it took down the entire bundle.  I have minimum links configured to 1 on the MLPPP interface.  I'm confused on why when one T1 goes down, it takes the entire bundle down??  Any suggestions?

Thanks, Karen