High Latency - Slow WAN Speeds

Unanswered Question
Jul 6th, 2008

I have an asymmetrical 8 Mbps/1 Mbps international cct between with Cisco 3845 routers on either end.

The latency is typically 800mS. The maximum TFTP transfer speed we can get accross the link (in either direction) is around 55KB and therefore not utilising the bandwidth effectively.

I read that tuning the buffers would help....but to what?

I have this problem too.
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Paolo Bevilacqua Sun, 07/06/2008 - 08:41

Hi, TFTP waits for acknowledge of each packet from the other side, so the performance you're obtaining is normal. You can only check if the server /client application has some tuning that can help.

You can check at show interface to see if any drop or queue can be improved, beside that, buffer should not have anything to do with the problem.

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seangregg Sun, 07/06/2008 - 09:48

Is there anything that can be done router-wise that will improve the performance of TCP/IP applications?

Are we stuck we the bandwidth delay product?

Paolo Bevilacqua Sun, 07/06/2008 - 09:55

Nothing can be done for UDP based applications, like TFTP is.

For TCP based, there are so called "satellite accelerators". Your provider should be able to suggest one, if not installed already.

You can also use an NM-VSAT with embedded accelerator, if supported by the network you're using.


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