Redistribution Case 2 (The infinite updates)
I am running a similar case to "Redistribution Case 2" in the INE v5 Workbook
in this topology,
The link between R1 and R3 run both OSPF and EIGRP, and they are adjacent with each other through both protocols.
Both R7 and R3 redistribute external prefixes with equal metric.
now, R7 redistribute its connected interface loopback0 10.0.7.7/32 into EIGRP, R2 receives this and advertise to R1 and R4,
R1 will redistribute it to OSPF and send it to R3 and R5, it will also send EIGRP update to R3
R3 will receive two updates to 10.0.7.7/32, one is EIGRP external with AD of 170 from both R1 and R4, and other OSPF external with AD of 110 from R1
R3 will prefer OSPF path and then redisitrbitue OSPF into EIGRP, and send update to R1 and R4,
when R1 receives this update, it will think R3 is closer to R7 loopback than R2, so it will install it and remove R2 route. Then it will again redistribute this update into OSPF and sends it to R3. R3 will redistribute it again into EIGRP. This update happens indefinitely
What I have noticed is that R1 flaps on 10.0.7.7/32 between R2 and R3, sometimes it install through R2, and after few seconds install it through R3,
R3 sometimes install 10.0.7.7/32 through OSPF through R1, and sometimes through External EIGRP through R1 and R4
regardless of the solution to this problem, and regardless of the infinite update between R1 and R3,
why would R1 and R3 flaps thier routes to R7, if they are only sending updates to each other, and this update carry same information?