BGP nexthop-self vs. EIGRP redistribution

Pekka Savola pekkas at netcore.fi
Wed Mar 18 04:48:18 CDT 2009


On Mon, 16 Mar 2009, Jack Bates wrote:
>>  My question is, which is the correct method of implementing this?  Should
>>  we be redistributing static and connected routes on our borders into IGP,
>>  and not using next-hop-self?  Or should we not redistribute and use
>>  next-hop-self?
>
> next-hop-self seems to remain more stable overall. In some scenarios I 
> believe it is even required (just as not using it is required in other 
> scenarios). For your deployment, I'd say you are open to choose either, and 
> next-hop-self would be the more stable of the two. The largest issue with NOT 
> using next-hop-self that I have seen is the effect it has when that IGP route 
> for the next hop disappears. BGP tends to be more graceful about removing 
> routes via iBGP then handling routes locally when they are suddenly 
> unreachable via IGP.

On smaller networks (where IGP size is not an issue), I could see some 
benefit for redistributing connected to IGP and preserving the 
next-hop for those interfaces which have a backup route through some 
other interface.  I.E: if the connected interface goes down, everyone 
knows immediately that the nexthop is unusable, and you can start 
using better working routes immediately, rather than waiting for the 
routes being BGP WITHDRAWn.

Loopback and n-h-s seems to always make sense for those interfaces 
which are singlehomed to that router (no redundancy) -- otherwise you 
may want to consider which one is best.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings




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