Re: Gap is only retransmitted once

[Mingyuan Zhu <liyha.zhu@xxxxxxxxx>]

I will rerun the test case to get the other two info:
# cat /proc/net/sctp/assocs
# cat /proc/net/sctp/remaddr


msw12:~ # sysctl -a | grep max_retrans
net.netfilter.nf_conntrack_tcp_timeout_max_retrans = 300
net.netfilter.nf_conntrack_tcp_max_retrans = 3
net.sctp.association_max_retrans = 10
net.sctp.path_max_retrans = 5


2011/2/16 Vasil Velichkov <vasil.velichkov@xxxxxxxxxxxx>:
> On 15.02.2011 15:58, Mingyuan Zhu wrote:
>>
>> Hi,
>>
>>
>>
>> I have observed a problem while doing load testing on SCTP. The tested
>> equipment is an open suse linux box with 2.6.34 kernel. The
>> application of the equipment will send/receive messages through linux
>> kernel sctp. The peer is an equipment using Aricent sctp stack.
>>
>> During the load testing, the peer equipment drops sctp chunks and
>> reports gaps through SACK to the tested equipment.
>>
>> The tested equipment (Linux box) retransmitts the missing chunks. But
>> it always retransmit the same #TSN only once even it receives more
>> SACKs with the reporting gap.
>>
>>  From the ethereal captures:
>>
>> - TSN 2254147468 is not received by the peer equipment, so it reports
>> the gap by SACK.
>>
>> - Linux box retransmit TSN 2254147468.
>>
>> - The peer still does not get it. It reports the gap by SACK again and
>> again.
>>
>> - Linux box never retransmit the missing chunk again.
>>
>> - Finally, neither linux box nor the peer can send/receive any more
>> chunks.
>>
>>
>>
>> Could someone help to look at the problem? Any help would be highly
>> appreciated!
>> --
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>>
>
> Hi Mingyuan Zhu,
>
> On the Linux box, check whether net.sctp.path_max_retrans(MAX_PATH_RTX) or
> net.sctp.association_max_retrans(MAXRT) parameters are set to 1.
>
> # cat /proc/net/sctp/assocs
>  ASSOC     SOCK   STY SST ST HBKT ASSOC-ID TX_QUEUE RX_QUEUE UID INODE LPORT
> RPORT LADDRS <-> RADDRS HBINT INS OUTS MAXRT T1X T2X RTXC
> f2876000 f35ee1c0 2   1   4  38050    1        0        0       0 6429275
> 2975   2985  *127.0.0.1 <-> *127.0.0.1            5000    32    32    5    0
>    0        0
> f444c800 e8407c00 2   1   4  41620    2        0        0     500 6429276
> 2985   2975  *127.0.0.1 <-> *127.0.0.1            5000    32    32    5    0
>    0        0
>
> # cat /proc/net/sctp/remaddr
> ADDR ASSOC_ID HB_ACT RTO MAX_PATH_RTX REM_ADDR_RTX  START
> 127.0.0.1  1 1 1000 5 0 0
> 127.0.0.1  2 1 1000 5 0 0
>
> # sysctl -a | grep max_retrans
> net.sctp.association_max_retrans = 10
> net.sctp.path_max_retrans = 5
>
> BR
> Vasil Velichkov
>
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