ECN

Sat Nov 8 16:31:43 UTC 2008

On Fri, 7 Nov 2008, Valdis.Kletnieks at vt.edu wrote:

> On Fri, 07 Nov 2008 08:27:58 +0100, Mikael Abrahamsson said:
>> for ECN to actually be useful, we (the ISPs) have to turn this option on
>> in the routers as well. Is anyone doing this today? What vendors support
>> it?
>
> The only thing that's *required* for it to help is that the routers and
> firewalls not actually *molest* the bits in the TCP SYN packet.  If you pass
> them and *do nothing else*, it at least has the potential of being useful at
> some other router along the path.  And let's face it - if *your* router is
> congested enough for ECN to matter, there's a fairly good chance that the
> router one hop up/downstream is *also* seeing some effects. Even if *you* don't
> do anything else, your neighbor might - helping you out in the bargain.

See:
http://www.icir.org/floyd/ecn.html
http://www.cisco.com/en/US/docs/ios/12_2t/12_2t8/feature/guide/ftwrdecn.html

-Hank