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

[Randall Stewart <[e-mail]>]

On May 26, 2009, at 9:58 AM, Joe Touch wrote:

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> Anantha Ramaiah (ananth) wrote:
>>
>>
>>> -----Original Message-----
>>> From: Fernando Gont
>>> [mailto:[e-mail]] On Behalf Of
>>> Fernando Gont
>>> Sent: Monday, May 25, 2009 8:19 AM
>>> To: Anantha Ramaiah (ananth)
>>> Cc: Joe Touch; [e-mail]; James Polk (jmpolk); tsvwg
>>> Subject: Re: [Tsvwg] WGLC for Port Randomization starts now
>>> (April 1st)
>>>
>>> Anantha Ramaiah (ananth) wrote:
>>>
>>>> Hmm.. I missed this one.. The draft which we had put out
>>> more than an
>>>> year ago DOES talk about keeping state at the peer to minimize
>>>> collisions. It lists a few algorithms to that effect as well.
>>> They probably mean that additional work is required only on
>>> the side that performed the passive close. (i.e., half of the
>>> work is already done).
>>
>> Any RFC compliant TCP implementation will honor TIME-WAIT requirement
>> and that involves keeping state at the side which initiated the
>> connection close.
>
> It's worth noting that many implementations aren't RFC compliant in  
> this
> regard, though.
>
>> It is also well known that the side-effect of
>> TIME-WAIT requirement leads for the 4-tuple (socket-pairs) to be  
>> locked
>> for some time.
>
> That is not a "side effect", that is the *desired* effect.
>
>> It needs to be pointed out at that, other transport
>> protocols like SCTP doesn't have the TIME-WAIT requirement since the
>> protocol supports in-built mechanisms to deal with the need for the
>> same.
>
> SCTP has a TIME WAIT state for its connection IDs (socket pair and
> vtags), just as TCP has for its (socket pair). The difference is that
> SCTP has a larger connection ID space, that's *all*.


Joe:

Technically you are correct... there is a timed-wait on vtags. The
BSD implementation (the reference implementation) does properly  
implement
this. However the space is so large most implementations do not do so.

I guess other developers have felt its not worth the trouble with such
a large space....

R



>
>
> Joe
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------------------------------
Randall Stewart
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803-345-0391(direct)