Re: Thoughts on address selection

[Stig Venaas <stig at venaas.com>]

Fred Baker wrote:
> On Nov 18, 2009, at 6:22 PM, Arifumi Matsumoto wrote:
>
> > I guess that is because if you force to try all the pairs, it perfectly
> > ignores the address selection manner defined in RFC 3484, and thus,
> > it gives us not little impact.
>
> If they space them closely and run them in parallel, I guess I don't see 
> the impact. Imagine you have five addresses and your peer has five 
> addresses, so there are 25 pairs. Imagine you are spacing the SYNs 10 ms 
> apart. Imagine that the only pair that works is the last one you try. 

I'm a bit worried about this. If e.g. the host is 100ms (RTT) away and
10 combinations work, you may end up creating TCP state (and getting
syn-acks back) on the destination host for 10 connections, while you are
only going to use one.

I feel the delay between then should ideally be a bit longer than the
RTT. Which is fine if you only try a few combinations. Of course one
problem is that you don't really know what the RTT will be.

Stig