Question

A network engineer configures mutual redistribution between BGP (AS 65100) and EIGRP (AS 10) on two border routers, R1 and R2, that both connect to the same BGP and EIGRP domains. External EIGRP routes learned from BGP on R1 are being redistributed back into BGP on R2, then re-advertised and reinjected into EIGRP, causing intermittent routing loops. The engineer wants to prevent routes that originated in BGP from being redistributed back into BGP. Which configuration on both routers best prevents this loop?

Accepted Answer

Apply a route map on redistribution from EIGRP into BGP that matches and denies routes tagged when they were redistributed from BGP into EIGRP, and set that tag during the BGP-to-EIGRP redistribution.

Answer

Increase the administrative distance of external EIGRP routes to 255 on both routers so they are not installed in the routing table.

Answer

Enable auto-summary in the EIGRP process so that the more specific BGP-origin routes are suppressed before redistribution.

Answer

Configure split horizon on the EIGRP interfaces facing the BGP border so the routes are not advertised back out.