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

[Iljitsch van Beijnum <iljitsch@muada.com>]

On 11-nov-04, at 15:13, Joe Touch wrote:

> Has anyone considered keeping the connection 'active' (i.e., 
> keepalives) for sessions for around 1-2 typical RTTs of idle? That 
> would catch TCP idles that still allow TCP bursts; anything longer 
> than that and TCP is supposed to 'restart' its congestion control 
> anyway.

> That might be a happy medium to the 'all or none' keepalive. I.e.,
> "keepalive for 1-2 RTTs of idle".

Hm, wouldn't just one or two RTTs be a bit short? You may still get a 
delayed ACK after 2 RTTs.

I think this basically boils down to the idea I was talking about 
previously, where there are only reachability checks when there are 
packets going in one direction. So when we transmit a packet, we start 
a timer. When we receive a packet, we cancel the timer. When the timer 
expires, we test reachability. Some optimization is possible with TCP 
so that we don't start the timer for ACK packets with no data, but we 
do stop the timer for those.