kernel: does not learn routes with RTPROT_KERNEL (proto kernel in ip-route(8) output)

[Ondrej Zajicek]

On Wed, Aug 07, 2013 at 02:11:46PM +0400, ???????????? ?????????????? wrote:
>  Hello.
> 
> Recently I spot following issue with BIRD:
>   kernel syncer does not learn routes with RTPROT_KERNEL even with
>     "learn" and "device routes" turned on.
> 

> Can some one explain why this was done, and is there any way
> other than patching BIRD (at least sysdep/linux/netlink.c does checking and ignoring
> and sysdep/unix/krt.c makes its final verdict to ignore such route).

Well, i don't know why kernel device routes are not imported in 'learn'
mode and instead direct protocol is used. Some of these reasons are
probably lost in the past (like in ancient Linux where device routes
have to be generated by user), another possible reason is that you still
need some external protocol for these routes - if you can learn kernel
device routes from kernel protocol but if you overwrite them by a route
from another protocol, then kernel protocol stops announcing such device
routes and the device route is not reintroduced when the other protocol
withdraws its route.

> Background of problem or why this might be important (at least for me).
> There is lot of text, and no need to read it, however it describes why learning
> routes with RTPROT_KENREL might be important.

Thanks for the explanation, problem with missing krt_prefsrc is interesting.
Perhaps the simple fix would be to add krt_prefsrc to routes generated
by direct protocol?

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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