Subject: [Tsvwg] SCTP Multi-homing

From: devayya <[email-masked]>
Date: Tue, 08 Aug 2006 15:32:29 +0530

Iam forwarding this to tsvwg also.. since I did not get any reply from 
sctp implementors list.

Hi,

Please consider the scenario, where one end (SUT) is multi-homed and the
other end is not. In that case, if DATA is sent to the peer by SUT from
primary and if there is no SACK, should the DATA chunk be retransmitted
from secondary?
As per RFC, I understand that the number of paths is decided based on
the number of peer addresses. Now, in this SUT is multi-homed, but its
peer is not. So, according to SUT, there is a single path. Should the
retransmission be done by SUT with secondary as source IP address?

thanks,
Devayya

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From: "Ashish Soregaonkar" <[email-masked]>
Date: Tue, 8 Aug 2006 16:25:55 +0530

Devayya,

RFC 2960 section 6.4.1 talks about source destination pairs to be considered
in a retransmission policy.

" When retransmitting data, if the endpoint is multi-homed, it should
consider each source-destination address pair in its retransmission
selection policy. When retransmitting the endpoint should attempt to pick
the most divergent source-destination pair from the original
source-destination pair to which the packet was transmitted. "
So in case the source endpoint is multi-homed and the destination is not,
the second source address will form a second source-destination pair with
the destination endpoint address.