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Frame-relay - major interface/subinterface

When you have a major interface at a host and it is a full T-1 you use the bandwidth statement 1544. What about the subinterfaces. Do you use 1544 or the actually bandwith provisioned at the remote. I see people using 1544 on the major interface and all the subinterfaces. what is correct? Thanks

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Re: Frame-relay - major interface/subinterface


I do not believe that there is any one answer that is right for every situation. In some respects the appropriate bandwidth to use may depend on the provisioning of the Frame Relay circuit - what is the bursting capability of the line. If it is possible to burst up to full line rate then perhaps 1544 is appropriate.

Also recognize that while the configured bandwidth may influence the calculation of metrics for some routing protocols, it does not operationally affect the interface or subinterface.




Re: Frame-relay - major interface/subinterface

As Rick said, that answer depends on your circumstances. While the bandwidth parameter does not impact the rate at which traffic is actually sent out the interface, it does impact a lot of other things:

- QoS policies applied to the sub-interface

- OSPF cost

- EIGRP packet pacing

Therefore, if you are using any of the above, it is advisable to tune the bandwidth to at least match the CIR of that particular PVC. When using EIGRP, you have to make sure that the sum of the bandwidths for each interface does not exceed the physical bandwidth of the link.

Hope that helps - pls rate the post if it does.


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