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 _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
