Re: Comments on draft-ietf-multi6-v4-multihoming-02

Iljitsch van Beijnum wrote:
> On 11-nov-04, at 2:50, Joe Touch wrote:
> 
>>>> So, are you suggesting that if we want to maintain any multihoming 
>>>> bindings,
>>>> we should rely on application layer keep alives?
> 
> 
>>> Certainly not. What I'm saying is that if applications want to be 
>>> sure a session remains available, they should send keepalives. Then, 
>>> if the session goes away, the app gets to hear about it without much 
>>> delay.
> 
> 
>> That's not true for TCP connections today, or anything below it - the 
>> session remains available until it is closed, even if unused. Doesn't 
>> this then change the semantics of 'application silence'?
> 
> 
>> I don't want unused sessions to consume bandwidth switching around, 
>> but they shouldn't go away per se.
> 
> 
> I completely agree. That's why the multihoming mechanism shouldn't do 
> keepalives on idle sessions. If the opposite behavior is desired, 
> applications or transports should do keepalives.

But that argues that applications are responsible for the use of 
multi6-based transport connections. Applications should (MUST?) be able 
to be ignorant of such use (otherwise all apps need revision).

Brian's note about NATs is useful in this context; this is another 
reason that complicates their use, not a reason to argue that 
applications are thus responsible. Apps. rely on transports to maintain 
state. TCP already supports connections that are silently (to the 
transport layer) maintained; anything short of that here is going to be 
a problem, IMO.

Joe

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