[e2e] TCP sequence number reset
detlef.bosau at web.de
Sun Mar 27 07:46:01 PDT 2011
On 03/25/2011 07:14 AM, Kacheong Poon wrote:
> What is your reason that a TCP connection cannot be seen as the same
> as an SCTP association with 1 single stream? And what is your
> reason that "reusing a stream" requires "resetting a stream"?
At least one reason is that a sequence number in TCP is never defined by
the user but negotiated in the startup phase of the flow.
Particularly, refer e.g. to RFC 793, recently used sequence numbers must
not be used for a certain period of time.
In my opinion, your problem is twofold.
First, you propose mechanisms, such as resetting a TCP sequence number
by the user, without giving a clear reason for doing so. And please keep
in mind, that in science, we must give valid reasons for taking a
certain decision. Particularly this holds true for adding mechanisms to
Second, and admittedly I'm not quite familiar with SCTP, so I don't know
the API/user view for it, any kind of protocol design is strongly
governed by the abstraction we wand to achieve and the behaviour, which
is presented to the user. And particularly, TCP provides a user with an
ordered and reliable stream of octets. Particularly, there is no random
access to this stream. In that respect, a TCP flow between two endpoints
resembles an inter process pipe. From that point of view, there is
absolutely no need for an application to deal with certain sequence numbers.
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