Subject: [Tsvwg] Source IP address Control

From: "Khan, Mohammad" <[email-masked]>
Date: Tue, 23 Apr 2002 20:51:43 -0700

Hi All,
One concern i have regarding SCTP source address control.
Can we keep the IP header source address of an outgoing sctp packet as one
which is down and this is known to peer through heartbeats
1)Should peer discard this data it receives from down interface address.
2)Should peer check the state of the peer address it is sending SACK,
HEARTBEAT-ACK, INIT-ACK and COOKIE-ACK.

Motive of doing this is implementation of Dynamic IP address modification
when i don't know the status of local interface IP address and one node e.g.
has four interface IP address A, B, C and D. One Endpoint E1 is using IP
addresses A , B, C and D and has opened an association A1 which has source
IP addresses A and B. If  I open IP_ANY socket for all the addresses on this
host and SCTP sends some data to the peer on association A1with source
address as A but even if A is down IP kernal shall send this packet out
through some other interface keeping header IP source address unchanged to
the network and the peer would receive the data but peer is knowing that
this interface A is down. Is it legal.

Regards
kashif khan

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From: Jacob Heitz <[email-masked]>
Date: Tue, 23 Apr 2002 21:51:01 -0700

I don't think it is illegal, but why would you want
to do this ?

If your peer receives a data chunk with source address
A, he will, with high probability, send a SACK back to
address A. He may SACK to another address, for example,
if he has his own DATA to send and piggybacks a SACK
on it. You should accept a SACK to any address belonging
to your endpoint. The main point is that you cannot
expect your peer to know that A is down and therefore expect
him to send the SACK to B. He MAY do this, but you cannot
expect that he will.

-- 
// Jacob Heitz. Tel:510-747-2917