JustKernel

While testing with ATM card, a thing that never expected occurred. If you transfer your UDP data to ATM card (configure map from udp and map to udp on ATM card), and loopback the traffic, then the UDP payload that you get back has corrupted data.

Just a simple UDP loopback test and UDP payload is corrupted on receipt. (Corrupted in the sense , the first three bytes of our payload were always overwritten with some different value).

Debugged a lot, scratched our head. While this simple test is failing. (We were using CPS protocol).

Finally, we came to know that when UDP payload is converted to Cell, three byte Cell header is added to it and when the cell is converted back to UDP payload, these bytes become part of UDP payload only.. Oh hhh..

SO you get back corrupted payload, with 3 bytes of your data missing.

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Anshul Makkar, anshul_makkar@justkernel.com

Originally Posted On: 2010-06-06 02:46:20

 

Tags: ATM loopback