[e2e] Can we revive T/TCP ?

Bob Braden braden at ISI.EDU
Fri Mar 24 11:11:15 PST 2006

At 07:31 PM 12/26/2005 +0100, Michael Welzl wrote:
>Hi everybody,
>Here's something that I've had on my mind for quite a while now:
>I'm wondering why T/TCP ( RFC 1644 ) failed. I mean, nobody seems
>to use it. I believe someone explained this to me once (perhaps even
>on this list? but I couldn't find this in the archives...), saying that
>were security concerns with it, but I don't remember any other details.

As the designer of T/TCP, I think I can answer this.  There are three
reasons, I believe.

(1) There are very few situations in which single-packet exchanges
     are possible, so T/TCP is very seldom a significant performance
     improvement.  But it does have significant complexity.

(2) Since the server is asked to do a perhaps signficant computation
     before the 3WHS has completed, it is an open invitation to
     DoS attacks.  (This would be OK if you could assume that all
    T/TCP clients were authenticated using IPsec,)

(3) I have heard rumors that someone has found an error in the
    specific state transitions, of T/TCP although I have never seen
    the details.

Bob Braden

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