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[Question #100514]: [ROHC v1.2.0 Tunnel Application] No observed feedback after lost

 

New question #100514 on rohc:
https://answers.launchpad.net/rohc/+question/100514

I'm running some experiments with the provided ROHC tunnel application to observe the effect of packet loss on the overhead of the protocol.  I'm using a UDP packet generator to send a stream over the tunnel.  The tunnel is started with the following parameters on both machines:

rohctunnel rohc0 remote 192.168.0.11 local 192.168.0.10 port 5000 error uniform 1e-4 dir bidirectional

My understanding is that these parameters should start the compressor and associated decompressor with a small BER and feedback enabled.  When streaming in one direction, it shows that packets are being dropped, but it does not reply with any feedback.  Wouldn't the context become invalidated?  An example of this behavior is shown below in the output of the decompressor on the receiving node.  Furthermore, no feedback is sent on initialization of the tunnel.  This makes me think that the mode is possibly stuck in unidirectional.  It never seems to switch into optimistic or reliable.  Is there a way to force the mode into optimistic or reliable?

Thanks for your help.

Cheers,
Ryan


[rohc_decomp.c:399 rohc_decompress()] decompress the packet #19255
[rohc_decomp.c:550 d_decode_feedback_first()] skip 0 byte(s) of padding
[rohc_decomp.c:560 d_decode_feedback_first()] add-CID present: 0xe3 -> CID = 3
[rohc_decomp.c:618 d_decode_header()] add-CID present: CID = 3 (0x3)
[d_generic.c:2446 d_generic_decode()] decode the packet (type 0)
[d_generic.c:2527 decode_uo0()] first byte = 0x57 (real CRC = 0x7, SN = 0xa)
[d_generic.c:3354 do_decode_uo0_and_uo1()] SN = 14154
[d_udp.c:489 udp_decode_uo_tail_udp()] UDP checksum = 0x1d95
[d_generic.c:5374 build_uncompressed_ip6()] Payload Length = 0x3000
[d_udp.c:544 udp_build_uncompressed_udp()] UDP checksum = 0x1d95
[d_udp.c:548 udp_build_uncompressed_udp()] UDP length = 0x0030
[d_generic.c:3490 do_decode_uo0_and_uo1()] size = 48 => CRC = 0x7
[d_generic.c:5683 update_inter_packet()] current time = 3870667462 and last time = 3870667370
[d_generic.c:5697 update_inter_packet()] inter_arrival_time = 569 and current arrival delta is = 92
[d_generic.c:2625 decode_uo0()] ROHC payload (length = 40 bytes) starts at offset 3
[d_generic.c:2458 d_generic_decode()] uncompressed packet length = 88 bytes
[rohc_decomp.c:411 rohc_decompress()] state in decompressor = 3
[rohc_decomp.c:484 rohc_decompress()] feedback curr -12
[rohc_decomp.c:491 rohc_decompress()] feedback curr 0
ROHC packet(s) probably lost between seq = 25132 and seq = 25135
[rohc_decomp.c:399 rohc_decompress()] decompress the packet #19256
[rohc_decomp.c:550 d_decode_feedback_first()] skip 0 byte(s) of padding
[rohc_decomp.c:560 d_decode_feedback_first()] add-CID present: 0xe3 -> CID = 3
[rohc_decomp.c:618 d_decode_header()] add-CID present: CID = 3 (0x3)
[d_generic.c:2446 d_generic_decode()] decode the packet (type 0)
[d_generic.c:2527 decode_uo0()] first byte = 0x6e (real CRC = 0x6, SN = 0xd)
[d_generic.c:3354 do_decode_uo0_and_uo1()] SN = 14157
[d_udp.c:489 udp_decode_uo_tail_udp()] UDP checksum = 0xa864
[d_generic.c:5374 build_uncompressed_ip6()] Payload Length = 0x3000
[d_udp.c:544 udp_build_uncompressed_udp()] UDP checksum = 0xa864
[d_udp.c:548 udp_build_uncompressed_udp()] UDP length = 0x0030
[d_generic.c:3490 do_decode_uo0_and_uo1()] size = 48 => CRC = 0x6
[d_generic.c:5683 update_inter_packet()] current time = 3870667555 and last time = 3870667462
[d_generic.c:5697 update_inter_packet()] inter_arrival_time = 330 and current arrival delta is = 93
[d_generic.c:2625 decode_uo0()] ROHC payload (length = 40 bytes) starts at offset 3
[d_generic.c:2458 d_generic_decode()] uncompressed packet length = 88 bytes
[rohc_decomp.c:411 rohc_decompress()] state in decompressor = 3
[rohc_decomp.c:484 rohc_decompress()] feedback curr -12
[rohc_decomp.c:491 rohc_decompress()] feedback curr 0

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