We receive full routes and a default so we can perform traffic engineering within our network. We have links to multiple carriers, via multiple routers. We inject a default route into OSPF from distinct segments of our network, based on receiving the default route on that segment via eBGP. If the default route goes down, the default injected from another segment assumes priority and traffic routes out through that segment's carrier. It's easier to manage this kind of failover (for us) using default routes, so we don't have to carry full routes on all our core routers. We also prefer using a default route over engineering things based on some other arbitrary route learned from eBGP.
Thanks, Adam -----Original Message----- From: NANOG [mailto:nanog-bounces+maillist=webjogger....@nanog.org] On Behalf Of Marc Storck Sent: Wednesday, November 05, 2014 6:53 AM To: nanog@nanog.org Subject: Re: Default routes on BGP routers with full feeds -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Nov 5, 2014, at 7:49 AM, Andreas Larsen <andreas.lar...@ip-only.se> wrote: There is one setup where you would need default route from your provider. If you have no IBGP between two sites and your prefix is a large /16 on side and maybe a /18 from that /16 on another site. These site would not be able to talk to each other if you orginate from the same AS. Other than that I see not harm in having both default and a full table since longest prefix match will always win even if you have 2 or more transits. I think in that case you would use “allowas-in”. Regards, Marc -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIcBAEBAgAGBQJUWg8PAAoJEBqZdpQUXtTCkr8P/j/V0nsJwS6UOhEBU0Cpvrlf BnhGgBy3exIiMq87IqO472P5Gkwsx52a/P5zUfuRDd3GKs1kNx4cyM6MH+XUFti0 f7kkKxDJ5hAne2Bg+KYLK/oLJUFC9gjSJM5AL8fjTb7qr+X2Wc2Wuqm/F346V3gQ cpO8lTuctM9pmBguAk8hCggKrsQBjDZJ7aF6qEebSdZHEG4JuONzx/2xFwq9vZMW 1lh+hyoGiVmb5dglma3525N0SbfJBbRgIFjcd7kQTq7toyRUytGecjpmXjCdomkG Y07Atj9T02w4M3h3dUpsAfXPRZhHuXBhDV24n0eBOnaJEwbEkdz5qfYjbXLVAItH 8yo8gtEYjzhPyfivdJ4YiZ97Yd4BID7boaiuyEBxczLfZ77Fm7XxPqbD+9K5+DJv VnyIt1adZkIcnoNSOOfJPswNT8Tfmz6r5F3l0+xa+ZnmCUgKZ8XtcHoLPYGR5ZMs mU6W7SsLSeX4QgO/2Ae+hmfV+jWcyNnt/Vs9MNqFkAbyjsjXX4H7gc88UKpPzvIq kkMzlKrk5hlXhZ6bQJWwIgX3PaDxD+YLa/nmq6/sgqA8rIKNiOVtNYWMbEkve5JJ l+RAA7foh22Sz0zCce6Rf/jmibBRAZ3GBD/UxV5bH+XB+vStlBZ8B8EHe22fwBaX BThfag88mErUm+MXKbar =qJ44 -----END PGP SIGNATURE-----
