Wireshark-users: [Wireshark-users] question about SCTP multi-homing
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From: WangWeiguo <encwgwg@xxxxxxxxxxx>
Date: Fri, 11 Mar 2011 02:03:08 +0800
Hi all,
Anyone can help with this SCTP multi-homing question?  I've read the spec. (RFC 4960) and googled, but still it's quite hard to really understand the essentials of the multi-homing.
 
The question is based on the diagram as following, which is a SCTP association beteen End Point A and B, on each End Point has two IP addresses serving this SCTP association:
 
Node A          Node B
IP A1   ------- IP B1
            \     /
              \ /
              /\
            /    \
IP A2   ------ IP B2
 
In this way, there are actually 4 physical links in this single association: A1 -> B1,  A2 -> B2, A1 -> B2, and A2 -> B1.
 
The question is: among these 4 links, how many can be defined as Prime?
From the spec., it looks like only one pair of IP addresses (ig. A1->B1) can be defined as prime so all traffic actually just goes on this link only, however in this way it means that among the 4 available links, only one is bearing traffic in normal cases and all other 3 are standby in case of prime failure, it doesn't look like make sense if compare to the possibility of having 2 out of 4 as prime and other 2 as standby. Furthermore, in case of prime (say A1-> B1) failure, which of the other three will take over and how are they prioritized?
 
Thanks.
 
Kevin. Wong.