Re: [Tsvwg] WGLC for Port Randomization starts now (April 1st)

[Joe Touch <[e-mail]>]

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See below; now I'm really confused:

Randy Stewart wrote:
> 
> On May 28, 2009, at 12:14 AM, Joe Touch wrote:
> 
> Randy Stewart wrote:
>>>> Not getting into the details of vtags.. I think you hit
>>>> upon the key point. If you are doing time-wait.. you are
>>>> doing time-wait on vtags... aka: 32 bit numbers.
>>>>
>>>> An IP address/Port is NEVER blocked from re-use right away
>>>> like it can be in TCP due to time-wait. This was always
>>>> one of the most irritating things I did not like in TCP.
> 
> Sorry, maybe I'm missing this.
> 
> Let A=srcIP, X=srcport, B=dstIP, Y=dstport.
> 
> In TCP, if I use A,X->B,Y, then close the connection, I cannot use it
> for another 2 minutes.
> 
> In SCTP, if I use A,X->B,Y with Vtag Q, then close the connection,
> clearly I cannot use A,X->B,Y with Vtag Q again for some (unspecified,
> AFAICT, in the specs) period of time.
> 
> You appear to be claiming that what SCTP does is block Vtag Q for that
> period of time _for all_ socket pairs. That's strictly worse than TCP
> was doing.
> 
> E.g., TCP has 32 + 16 + 32 + 16 bits to play with for connections as a
> whole, i.e., 96 bits. SCTP would have only 32. A large server with a lot
> of short connections could easily have vtag collisions in that situation.
> 
> 
>> No actually Q is blocked ONLY for the socket pair
>> A,X -> B,Y for 2MSL.

I don't see 2MSL anywhere in the SCTP spec.

Your earlier note said you blocked Q for all sockets; this says you
block only within the socket pair -- which is basically what I've been
saying all along - you block on the full connection ID, i.e., [A,X,B,Y,Q].

Joe
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