rohc

sn_wraparound

Asked by regulararmy

hello Didier,

  in 1.7.0lib. the attempt_repair() is diabled,
 when crc failed, especially when the sn_wraparound happens, how can we do,let the err go?

Thanks.

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Didier Barvaux (didier-barvaux) said : 		#1

Hello,

I'm not sure to fully understand your question. I'll try to rephrase it to highlight my understanding. Tell me if I'm right or wrong.

You are using the ROHC library 1.7.0. You disabled the repair mechanism that may improve recovery upon CRC failures. With that setup, you encounter CRC failures while decompressing some network flows. Is it correct?

Is there some packet loss that might explain the CRC failures ? Or some packet reordering ?

If not, the failures should not happen. It might be some bugs in the ROHC library or in your program. Maybe related to SN wraparound. Version 1.7.0 is 4 year old. Try upgrading to the latest version. If problem still occurs and it is reproducible, please send me a network capture of the faulty flow. I'll analyze and fix the problem

If there is loss or reordering, try to increase the robustness of the compression with the library API. Upgrading is also a great idea. Newer versions are more robust to packet loss than old ones, such as 1.7.0.

Regards,
Didier

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regulararmy (regulararmy) said : 		#2

Yes,you are right.
 "If not, the failures should not happen. It might be some bugs in the ROHC library or in your program. Maybe related to SN wraparound. ", if I disable the repair mechanism that may improve recovery upon CRC failures. With that setup,the lib can handle the SN wraparound? if not, the lib must be used with the repair mechanism opened?

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Didier Barvaux (didier-barvaux) said : 		#3

Hello,

If there is no packet loss, the library should handle SN wraparound fine, even if CRC repair is disabled. If you encounter such a situation, please capture the network flow that causes the problem, and send me the PCAP file. I'll analyse the problem. Tell me also what configuration do you use for the ROHC library (small/large CIDs...).

Regards,
Didier

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regulararmy (regulararmy) said : 		#4

It is diffcult to get the PCAP file, I will try .

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Launchpad Janitor (janitor) said : 		#5

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

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Didier Barvaux (didier-barvaux) said : 		#6

Hello,

Any chance to get the capture ?

Regards,
Didier

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regulararmy (regulararmy) said : 		#7

Hello Didier,

I am sorry I have no permission to get the capture in the equipment , but in the end, I find the CRC failures is caused by the APP, not the lib bug. sometimes APP will loss packets.

best regards

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regulararmy (regulararmy) said : 		#8

During this period, sometimes It is diffucult to access the lib website,sorry to reply too late

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Didier Barvaux (didier-barvaux) said : 		#9

ok, thank you for the feedback