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
