TO: Mr. Borkmann Good day! Thank you very much for your quick reply. I need to confirm if your environment there with 2 machines with 5 interfaces each have the same RHEL and LKSCTP versions with the ones we are using? If you are using the latest RHEL and LKSCTP versions and HB-ACKS are doing fine there, we might think that our older LKSCTP version has something to do with the abnormal HB-ACK behavior. Thanks, W. Tizon On Mon, 30 Jun 2014 10:24:09 +0200 Daniel Borkmann <dborkman@xxxxxxxxxx> wrote: > On 06/28/2014 01:04 PM, Winston V. Tizon wrote: > > Hello everyone! > > > > We are having some issues regarding SCTP multihoming > > and we would like to ask your opinion on this matter. > > We have two RHEL6.4 (2.6.32-358.el6.x86_64, lksctp-tools > > -1.0.10-5(64 bit)) machines connected by two L2 switch > > and a L3 switch (please see "Environment Setup" below). > > When we execute SCTP connection (using multihoming) between > > the two machines, the following behavior occurred: > > > > CLIENT L2 and L3 SERVER > > Secondary Primary | Primary Secondary > > | | | | | > > | | | | | > > | |INIT-INIT_ACK | | | > > | |<-------------|--------->| | > > | |COOKIE_ECHO-COOKIE_ACK | | > > | | | | | > > | |<-------------|--------->| | > > | |HB/HB_ACK | | | > > | | | | | > > |<-------|--------------|----------| | > > | | | HB | | > > | |--------------|--------->| | > > | |HB_ACK | | | > > | | : | | | > > | | : | | | > > > > INIT/INIT_ACK handshake occurred in the primary > > path of both machines which is expected. When a > > Primary path sends HEARTBEAT to another Primary, > > HEARTBEAT_ACK was returned to the sender. But > > when a Primary path sends HEARTBEAT to a > > Secondary path, the HEARTBEAT_ACK chunk was sent > > by the Primary path. We expect that the > > HEARTBEAT_ACK would come from the Secondary. > > > > [Questions] > > 1. Is this a normal behavior with regards to SCTP multihoming? > > So looking at the RFC, it says (RFC4960, 3.3.6. + 6.4.) ... > > An endpoint should send this chunk to its peer endpoint as a > response to a HEARTBEAT chunk (see Section 8.3). A HEARTBEAT ACK > is always sent to the source IP address of the IP datagram > containing the HEARTBEAT chunk to which this ack is responding. > > [...] > > An endpoint SHOULD transmit reply chunks (e.g., SACK, HEARTBEAT ACK, > etc.) to the same destination transport address from which it > received the DATA or control chunk to which it is replying. This > rule should also be followed if the endpoint is bundling DATA chunks > together with the reply chunk. > > ... it would be more correct to reply via the same transport, imho. > I just checked upstream kernel with multihoming on 2 machines with > 5 interfaces each, and HB, HB-ACK replies seem to be fine there, > that is, HB-ACKs go via same transports. > -- > 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
