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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