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New Member

MTU size

Dear all,

We have a 64Kbps Leased Line Frame relay Circuit connecting Two Inter-city networks . We have found that because of Congestion in the Link , Round trip time shoot up to 1600 ms frequently.

The Current MTU size is 1500 . What is the recommended MTU size for the above bandwidth line to eliminate Line saturation.

Any other Recommendations to Improve the performance ?




Re: MTU size

The MTU is OK as it is. Smaller MTU will result in more encapsulation overhead. The long delay will most likely be caused by congestion in the Frame relay cloud. You cannot do much about that except swithing to another provider when you are not satisfied with the current servicelevel.

To improve performance on low-speed lines (<128k) consider implementing ip tcp header compression.

New Member

Re: MTU size

And be carefully with the CPU on router when you implementing ip tcp header compression. Because this operation use a lot CPU.


Re: MTU size

Make sure you have fast switching turned for your interfaces . Doing a show "ip interface" will tell you whether fast switchis turned on , is the processor running high ? If it's the frame you should be seeing "FECN"s and BECN's on the frame interfaces if it's congested .

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