rohc

can a ROHC decompressor recieve a packet with all zeroes?

Asked by Sankar Malladi

Hi
Lets say if my decompressor is receiving packets and it is able to decode them successfully . Out of nowhere, my decompresor received a packet with 5 octets all of zero data. and this caused my rohc LIB to fail to decode even the next correct packets coming there in.
NOw my question is:
a. Is ROHC lib expected to receive all zeroes of data at all?
b. can we attribute this to other side of the network?
c. should we drop the all zeroes packet immediately?
d. or should decompressor recover her by itself and then start sucessfully decompressing the packets after may be 2-4 failures?

pls suggest?

thanks
Sankar

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Didier Barvaux (didier-barvaux) said : 		#1

Hello,

> a. Is ROHC lib expected to receive all zeroes of data at all?

Packets with zero bytes may be valid ROHC packets. A UO-0
header with small CID = 0 is one-byte length and that byte
may be zero. Such a ROHC header may have a 4-byte length
payload of zero bytes. This results in a 5-zero-byte packet.

> b. can we attribute this to other side of the network?

I don't understand your question. Could you please rephrase?

> c. should we drop the all zeroes packet immediately?

According to the answer to question a/, I would say no.

> d. or should decompressor recover her by itself and then
> start sucessfully decompressing the packets after may
> be 2-4 failures?

It really depends on several things:
 - the compression profile in use,
 - the mode and state of the decompressor,
 - the kind of decompression failure caused by the 5-zeroes
    packet,
 - the following packets that cause the next decompression
    failures.

To help you, could you provide me either a PCAP capture of the
faulty stream and/or the library logs at the time of the
decompression failures.

Regards,
Didier

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Launchpad Janitor (janitor) said : 		#2

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