Re: a_rwnd=0 - heartbeat messages allowed?
Michael Tüxen <[email protected]>
| Newsgroups | gmane.ietf.sigtran |
|---|---|
| Message-ID | <[email protected]> |
On Jan 21, 2010, at 12:38 PM, Brian F. G. Bidulock wrote: > Des, > > This is really an SCTP question (for [email protected]), however, > an SCTP endpoint is allowed to send SACK with rwnd=0. The > tester may send it; however, the tester must also send HEARTBEAT > ACK in response to HEARTBEAT if it wants to keep the association > alive. The SUT acts as an echo server. So the point here is to verify that the SUT reflects the received DATA after having received the SACK(arwnd=0). > > I would guess that the tester is testing zero-window probing by > the SUT, RFC 4960 6.1. A: > > When the receiver's advertised window is zero, this probe is > called a zero window probe. Note that a zero window probe SHOULD > only be sent when all oustanding DATA chunks have been > cummulatively acknowledged and no DATA chunks are in flight. Zero > window probing MUST be supported. > > If that is the case, it is expecting DATA not HEARTBEAT, and > this may be why the test case is failing (timing out) rather > than responding properly to the HEARTBEAT with HEARTBEAT ACK. The Tester expects a DATA chunk so it ignores the HEARTBEATs. > To be conclusive that the SUT is failing a zero-window probe > test, it needs to be verified that the SUT has DATA oustanding > after receiving SACK (rwnd=0). The SUT has data to send (that is why the tester is sending DATA), so it MUST send it even if the arwnd is 0. The SUT is NOT sending it, so it failed the test. > > One way for the tester to conclude this (if it is unable to do > so by ferry-clip) would be to send HEARTBEAT ACK and SACK > (rwnd=1500) in response to the first HEARTBEAT and see if the > SUT sends DATA immediately, in which case it might conclude that > the SUT has failed a zero-window probe test. The objective to test is: Does the SUT send zero window probes when the peer window is 0. The SUT fails this... > > --brian > > Des Smyth wrote: (Thu, 21 Jan 2010 09:29:12) >> >> Hi all >> >> >> >> I am conformance testing a Sigtran stack and I am trying to figure out >> if the behaviour described below is correct: >> >> >> >> Tester SUT >> >> <---------- DATA >> >> SACK (rwnd=1500) -----------> >> >> SACK (rwnd=0) -----------> >> >> DATA -----------> >> >> <----------- SACK >> >> <----------- HEARTBEAT >> >> <----------- HEARTBEAT >> >> <----------- HEARTBEAT >> >> <----------- HEARTBEAT >> >> association down. >> >> >> >> Should the SUT send a SACK for the DATA with tester rwnd=0? >> >> If this is ok, should SUT send HEARBEAT with rwnd=0? >> >> >> >> Any comments appreciated. >> >> >> >> Regards, >> >> Des > >> _______________________________________________ >> Sigtran mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/sigtran > > > -- > Brian F. G. Bidulock > [email protected] > http://www.openss7.org/ > _______________________________________________ > Sigtran mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/sigtran >