Question

Two ASBRs (R1 and R2) both perform mutual redistribution between OSPF and RIP. After the change, a RIP-learned prefix 10.50.0.0/24 originated behind R1 is being reinjected back into RIP by R2, creating a routing loop that surfaces as intermittent reachability. You want to use OSPF route tagging to break the loop without static filters per-prefix. Which configuration correctly prevents routes that originated in RIP from being redistributed back into RIP by the other ASBR?

Accepted Answer

On redistribution from RIP into OSPF, set tag 100; on both ASBRs deny any OSPF external route with tag 100 when redistributing OSPF into RIP.

Answer

On redistribution from OSPF into RIP, set tag 100; then permit only routes with tag 100 when redistributing RIP into OSPF.

Answer

Configure a distribute-list on the OSPF process denying 10.50.0.0/24 inbound so the tag is never learned.

Answer

Set the OSPF external route type to E1 during redistribution so the accumulated metric prevents the loop automatically.