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Re: SCTP Mulithoming Communication PATHS Query

2010-04-16 02:33:40
Hi Samba,

It seems there is firewall between host-X and host-Y, so the cross path packets 
can not reach the destination?

In my understanding, some aspects may impact the result.

As far as I know, different vendors maybe provide different implementation.

some provide parallel path, like

                (px) ----- (py)
A: host-X                           host-Y
                (ax) ----- (ay)

while some provide both parallel and cross path, like

                 (px) ------ (py)
B:  host-X             X            host-Y
                 (ax) ------ (ay)

So, if host-Y takes implementation A, I guess the result would not change even 
you re-configure the network, because host-Y would
not return HBAck in the cross path when it receives the HB message (it doesn't 
think the cross path is SCTP PATH), I did ever see
such device.

But, the more important point is host-X, it looks very strange.

1. to mark the destination endpoint IPay as NETWORK DOWN on Host-X when  it 
exceeds max retranmission in same path(cross)
consecutively and

If the path of IPax -- IPay is OK, this should not happen, this is the key 
point.
Host-X would also send HB to IPpy by the source address IPpx, and send HB to 
IPay by the source address IPax, and the corresponding
HBAck would be returned by host-Y, so num of retransmission would be reset to 
0. In the viewpoint of host-X, the right result should
be: parallel paths are both OK and cross paths are both invalid, but the 
association should be OK.

Do you see the HB message (or DATA chunk) in the parallel path? or host-X only 
sends HB in the cross path?

By the way, tsvwg(_at_)ietf(_dot_)org is a better list for this discussion.

Regards
Xiangsong

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