Subject: Questions regarding to the basic concept of SCTP ...

From: Patrick Lam <[email-masked]>
Date: Wed, 26 Sep 2001 17:56:43 -0700

Hi:

I have some doubts about the basic concept of SCTP.  Please clarify what
I understood about it.  Here are how I interpret SCTP:

1.  Between any 2 end-points, a SCTP association can have multiple
physical connections.  To the user of SCTP, these multiple ethernet
connections will appear as just 1 association.

2. All these physical connections (corresponding to the SAME SCTP
association) can belong to different networks.

3.  Assuming some of the physical connections went down, as long as
there is at least 1 physical connection up and running, the SCTP user
shouldn't notice any difference at all (in terms of bandwidth and
connection state).

4.  In the socket level, regardless to how many physical connections
that 1 association correspond to, the application only knows about 1
file descriptor after calling socket.

Are my interpretations correct?

If so, how do we represent the endpoints with multiple IP addresses?  Or
is 1 endpoint only represented by 1 IP address somehow?

Also, in terms of SS7 links, does 1 SCTP association correspond to 1
link?  If so, according to Figure 10 of M2PA draft v03, where 2
associates are setup with 1 physical ethernet connection, we can setup 2
SS7 links on 1 physical connection.  Is this interpretation correct?

Please correct me if I am wrong.

Thanks very much in advance,

Patrick.

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From: Arun Prasad <[email-masked]>
Date: Thu, 27 Sep 2001 14:33:34 +0530

Hi Patrik,

yes...

yes..

The association as such will not be disturbed, the packets keep flowing between the
endpoints.
But in terms of Bandwidth, it depends on the network of the new path.

yes..

    Actually each connection or associatiion of SCTP can have multiple local Ip
address and mulpile destination Ip Addresses.
The User of SCTP should give the list of  Local IP Addresses on which he is wishing to
receive packets from the peer.
The same way the peer will also do... so both the endpoints will exchange the list of
ip-addresses and will use the alternative
addresses if one of the paths is corrupted....

  Thanks

-arun

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