Removing T/TCP and replacing it with something simpler

Andre Oppermann andre at
Fri Nov 5 09:31:48 PST 2004

Karim Fodil-Lemelin wrote:
>     In the case where all connections go through the SATLINK and are
> splitted by proxies, it make sense to use this knowledge and not
> renegotiate cookies for every connections since we know there is only
> one path to the internet and that all SATLINK connections will support
> (T/TCP or whatever name it will have). Do you have any plan to include
> that knowledge in your design or is it too much of a special case to
> really care?

It does not renegotiate cookies for every connection.  Only the first
connection will do that.  Re-seeding of the cookies will happen trans-
parently.  You pay the 3WSH tax only once for the first connection, or
the first connection after a longer idle time when the cookie expired.


> Andre Oppermann wrote:
> >Karim Fodil-Lemelin wrote:
> >
> >
> >>Now,
> >>
> >>    I have a question. In our application which can be described as:
> >>
> >>Client ----> (Client Gateway) -------> SATLINK ------> (Server Gateway)
> >>-----> Internet
> >>
> >>We act as the Internet servers (transparent proxies) and therefore T/TCP
> >>traffic is only sent over the SATLINK. In the current T/TCP
> >>implementation the sender has to send a ccnew option to discover that
> >>the server side supports T/TCP. Now we had to modify this so the
> >>gateways uses the knowledge that they work together and they don't need
> >>to send a ccnew option everytime a client makes a connection to a new
> >>server.
> >>
> >>My question is: In the new implementation does the cookie will be
> >>generated per machine or like the tao mecanism will it be based on a src
> >>/ dst tuple?
> >>
> >>
> >
> >The new cookie system will use the src-host/dst-host tuple.  The first
> >tcp connection between two hosts (port numbers are irrelevant) is a
> >normal three-way handshake and the cookie is exchanged.  From then on
> >it skips over 3WHS on the server if the cookie matches.
> >
> >
> >
> --
> Karim Fodil-Lemelin
> Lead Programmer
> Xiphos Technologies Inc.
> (514) 848-9640 x223
> (514) 848-9644 fax
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