On 12/14/2015 11:05 PM, Sun Paul wrote: > Thank Vald. > > is it possible to let me know how I can identify the windows side from > packet trace? is it the a_rnwd? That's is the announced receive window (how much buffer space the receiver has available). -vlad > > - RBK > > On Tue, Dec 15, 2015 at 11:38 AM, Vlad Yasevich <vyasevich@xxxxxxxxx> wrote: >> On 12/14/2015 08:13 PM, Sun Paul wrote: >>> Hi All >>> >>> I would like to check how LKSCTP handle late arrival of SACK. >>> >>> Our application is a DIAMETER based application running over SCTP, and >>> we found a strange behavior that if we send out DIAMETER request in a >>> batch, says 10 requests, the remote end point do not response at once, >>> and maybe after 5 secs, they response back with 10 SACKS. >> >> The fact that you get 10 SACKs back means that you are transmitting >> each DIAMETER request individually. So while at the DIAMETER level you >> may be batching, SCTP isn't bundling messages. >> >> Your statement about getting sacks back after 5 seconds leads to me >> believe that you have a very long rtt in your setup for some reason. >> 5 seconds is really excessive... >> >> There could be multihoming issues or something else and without more >> information it's hard to say. >> >>> >>> If in this case, will the LKSCTP libraries wait for the SACK before >>> sending the new request? Or, it is actually controlled by user >>> application level? >> >> The amount of data SCTP can have outstanding is governed by available >> congestion window and receive window. Once either of those windows >> is full, SCTP will not transmit more data until the window opens again. >> The windows will using open when a SACK arrives acknowledging that >> data. >> >> If a SACK isn't receiving within the round trip time, a retransmit is >> triggered. Late SACKs will not update the rtt, but will still open windows >> for more data to be sent. >> >> -vlad >> >>> >>> Thanks >>> >>> - RBK >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-sctp" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
