From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vasil Velichkov Date: Tue, 15 Feb 2011 16:01:08 +0000 Subject: Re: Gap is only retransmitted once Message-Id: <4D5AA344.9010107@opencode.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sctp@vger.kernel.org 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! > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > 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