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[Question #215668]: Ethernet transport app for ROHC Pkts

To: rohc@xxxxxxxxxxxxxxxxxxx
From: Raman Gupta <question215668@xxxxxxxxxxxxxxxxxxxxx>
Date: Fri, 30 Nov 2012 15:35:59 -0000
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New question #215668 on rohc:
https://answers.launchpad.net/rohc/+question/215668

I was trying to write a Ethernet based transport app similar to rohctunnel(tunnel.c) on 1.4.1 release. After some testing with a few RTP pcaps I found that Ethernet's minimum payload is 46 bytes and it adds padding for any payload less than that size. Thus decompression fails due to CRC mismatch for pkts less than minimum size. Since ROHC depends upon lower layer to give the length information which Ethernet header does not provide(cannot use EtherType for length) so I am thinking to add length byte infront of compressed ROHC pkt similar to current sequence bytes, before sending it on Ethernet. Other end will read this as length of compressed pkt instead of length returned by Ethernet interface.

If I replace sequence bytes with length byte what impact it will have? Any other thoughts on this issue.

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