[Bloat] ECN blocking router found

[Rui Paulo]

On Apr 13, 2011, at 9:44 PM, Dave Taht wrote:

> In my travels this month I have been testing ECN enablement at homes and hotels everywhere I go.
> 
> Until today, I was able to have the following settings for ECN on my laptop everywhere I've been.
> 
> net.ipv4.tcp_ecn=1
> #net.ipv6.tcp_ecn=0
> net.ipv4.tcp_sack=1
> net.ipv4.tcp_dsack=1
> 
> However, I got to visit Brian Clapper [1] (friend/co-author of gnugol) tonight, and discovered that his fairly recently purchased router, a:
> 
> Etherfast Cable/DSL router Model BEFSR41
> Firmware version 2.0.0.4
> 
> flat out refused to pass ECN enabled connection attempts (returning an ICMP unreachable message)
> 
> He'd not noticed the problem because ubuntu 10.4 (at least, he also runs bsd) has tcp_ecn=2, which so far as I know "tries" a ECN enabled connect then falls back to not using it.
> 
> I'm bummed that such a recent router doesn't pass ECN, and will look into the problem further in the morning.
> 
> So I think we must use tcp_ecn = 1 to TEST to make sure ECN is being passed, and tcp_ecn=2 as the default recommendation.
> 
> Perhaps we can synthesize TCP streams to more directly test ECN capability in the future somehow as part of our testing tools. Are there any tools that synthesize TCP/ip we could use as a starting point?

Are you looking for something like this?
http://www.icir.org/tbit/index.html#ECN

Regards,
--
Rui Paulo