On 07.03.2013 14:38, Ermal Luçi wrote:
On Thu, Mar 7, 2013 at 12:55 PM, Andre Oppermann <an...@freebsd.org
<mailto:an...@freebsd.org>> wrote:
On 07.03.2013 12:43, Alexander V. Chernikov wrote:
On 07.03.2013 11:39, Andre Oppermann wrote:
On 07.03.2013 07:34, Alexander V. Chernikov wrote:
Hello list!
There is a known long-lived issue with interface routes
addition/deletion:
ifconfig iface inet 1.2.3.4/24 <http://1.2.3.4/24> can fail if
given prefix is
already in
kernel route table (for
example, advertised by IGP like OSPF).
Interface route can be deleted via route(8) or any route socket
user
(sometimes this happens with
popular opensource daemons like bird/quagga).
Problem is reported at least in kern/106722 and kern/155772.
You patch is a welcome addition.
This can be fixed the following way:
Immutable route flag (RTM_PINNED, added in 19995 with 'for
future use'
comment) is utilised to mark
route 'immutable'.
rtrequest1_fib refuses to delete routes with given flag unless
RTM_PINNED is set in rti_flags.
How do the routing daemons react to being unable to change/delete
such a route?
routing daemons live long with the fact that there route socket cmds can
fail (and the is route(8) utility which can do anything), so typically
bird/quagga yells like
'bird: KRT: Error sending route 11.0.0.0/24 <http://11.0.0.0/24> to
kernel: File exists'
and marks given route as not installed in internal RIB. Additionally,
daemon will probably re-try to insert such routes on every periodic KRT
rescan (tens of minutes).
Isn't it better to teach the routing code about metrics.
Routing daemons cope better this way and they can handle this.
So the policy of this behaviour can be controled by administrator rather than
by code!
With metrics you can add routes with bigger metric for interfaces and lower
from routing daemons.
This also can mitigate somehow on interfaces with the same subnet configured
possibly.
Generally I agree with you that this would be the ideal outcome.
However we're still quite a bit away from reaching that goal.
To make this really work we have make mpath plus metrics a first
class citizen in the routing code and also the update the routing
daemons kernel interfaces to know about this. I hope we get there
in the not too distant future.
As a first step I think it is important that Alexanders patch goes
in to fix a long standing and very annoying problem with the code
we have. Also the link down route withdraw should be added asap.
Then we can take the next steps towards the ultimate goal you describe.
I hope you do not object to Alexanders patch?
--
Andre
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