BGP nexthop-self vs. EIGRP redistribution

phil at mindfury.net phil at mindfury.net
Mon Mar 16 11:20:08 CDT 2009


...which is better?

We recently ran into what looks like an implementation flaw in our network
design.  After moving two GbE connections with Savvis (same edge device on
both ends) into EBGP-multihop, we were encountering problems with iBGP
churn.

The network design is two buildings in the same AS, each building has two
core switches, which are in a full iBGP mesh, and acting as
route-reflectors for four border switches.  Two border switches are in one
building, the other two in the other building.  The layout is shown here:

http://img17.imageshack.us/img17/6562/bgplayout.jpg

EIGRP is being used as the IGP, now border4 is the the newest switch to
have been installed, and in it's EIGRP configuration, static and connected
routes were being redistributed.  The other border switches, however were
not redistributing.  They were using next-hop-self in their iBGP
announcements to the cores.  We ended the iBGP churn issue by changing
border4 to use next-hop-self to cores 3 and 4.

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?

--
Philip L.




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