On Wed, Jul 29, 2009 at 12:07:11PM -0400, Doug Graham wrote: > On Wed, Jul 29, 2009 at 11:19:08AM -0400, Vlad Yasevich wrote: > > >> 7 2.000205 10.0.0.15 10.0.0.11 SCTP DATA > > >> 8 2.000501 10.0.0.11 10.0.0.15 SCTP SACK DATA > > >> 9 2.200484 10.0.0.15 10.0.0.11 SCTP SACK > > > This is what I would expect. > > > > Hmm... time to re-read 6.1 and 6.2... > > [...] > > Since we received only 1 packet so far, the SACK is delayed. The implementers > > have focused on section 6.2, but seemed to have ignored the following text > > from 6.1: > > > > Before an endpoint transmits a DATA chunk, if any received DATA > > chunks have not been acknowledged (e.g., due to delayed ack), the > > sender should create a SACK and bundle it with the outbound DATA > > chunk, as long as the size of the final SCTP packet does not exceed > > the current MTU. See Section 6.2. > > > > Looks like BSD does this and linux doesn't appear to. Linux has been doing this > > since the beginning... > > > > Doug, can you regenerate you patch with proper commit comment and sign-off > > (according to Documentations/SubmittingPatches). > > I just sent a patch, but please keep in mind that I am not by any means > an expert on this code. I've tested my patch only under conditions > where no packet loss was occurring, so I can not vouch for its behaviour > when losses do occur, nor do I know how it will interact with features > that I haven't used during testing. However, to the best of knowledge, > this patch does correctly implement the intended sematics of RFC 4960. Oh yeah, I should also mention that I still don't understand what the original 'asoc->a_rwnd > asoc->rwnd' condition was all about. I replaced that condition with timer_pending(), but if the original condition really does have something to with sending window updates as you mentioned, it's possible that it should be left in as well. ie: if ((asoc->a_rwnd > asoc->rwnd) || timer_pending(timer)) but then keep in mind that the body of that if block has been rewritten to assume that the timer is pending if the block is executed. If the block can be entered as a result of either of these two conditions, that assumption may no longer be true. --Doug. -- 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
