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(usagi-users 04099) Re: Default Router Preference - RFC4191, default route switching


Linus LÃssing <linus.luessing@xxxxxx> writes:

> [snip]
> Cool! I now did some new tests with a custom-build
> kernel. It seems to work a little better, in that it now also
> switched the default route. The new netcat session goes over the
> right prefix and to the right router with the high preference.
> However, there still seems something wrong: The old netcat
> connection still uses the old prefix (which is good, otherwise I'd
> lose the connection, of course), but new packets take the
> high-preference default route immediately - which is going to fail
> if the gateway routers / the ISPs behind them do strict subnet
> checking. 

Yes. I would have to reread the RFC (4861, 4191, 2461, 4863, ...?) to
check what the expected behavior is: IIRC, the prefix is associated with
the subnet (the link) and not the router. If I am right, the behaviour
you get makes sense.

> And just for clarification, a route ::/0 with the same preference
> is probably superfluous, right (though I tested both with the same
> result)?

I implemented that a long time ago in UMIP and do not remember what the
kernel maintains, i.e. one or two routes.

> The gateway is running a 2.6.32 kernel by the way.

That's a good version (stable and maintained).