Re: [RFC] Vegas and tcp parameters per route

["David S. Miller" <davem@redhat.com>]

On Mon, 15 Mar 2004 13:30:34 -0800
Stephen Hemminger <shemminger@osdl.org> wrote:

> > How do you propose to support some kind of "global enable" for features.
> 
> The easiest way to do that is to initialize each TP with features from
> sysctl when created.

Right.

> > I think sysctl's support this quite well.  The test for the feature
> > becomes "sysctl || route_attribute".
> 
> That is what the next version does for FRTO.

OK, but do not limit it to FRTO, I think all TCP features should
be handle'able this way.

Actually, this is a problem with using an RTAX_* that is a bitmask
or single binary.  You need a "don't care" value, and thus effectively
a trinary route entry state to do this properly.  Right?

In this way, you have a global default, but you can also FORCE something
off per-route.  People can work-around ECN-fux0red sites without obviating
ECN completely.

Or perhaps you can come up with another method by which to achieve this?

> Okay, what about WESTWOOD?
 ...
> What about tcp_westwood which is new?

Just don't change sysctl numbers, even we keep them perfectly sync'd between
2.6.x and 2.4.x sources.