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Topic starter
20/05/2022 11:49 am
Refer to exhibit.
Routing protocols are mutually redistributed on R3 and R1. Users report intermittent connectivity to services hosted on the 10.1.1.0/24 prefix. Significant routing update changes are noticed on R3 when the show ip route profile command is run .
How must the services be stabilized?
- A . The issue with using BGP must be resolved by using another protocol and redistributing it into EIGRP on R3
- B . The routing loop must be fixed by reducing the admin distance of iBGP from 200 to 100 on R3
- C . The routing loop must be fixed by reducing the admin distance of OSPF from 110 to 80 on R3
- D . The issue with using iBGP must be fixed by running eBGP between R3 and R4
Suggested Answer: B
Explanation:
After redistribution, R3 learns about network 10.1.1.0/24 via two paths:
+ Internal BGP (IBGP): advertised from R4 with AD of 200 (and metric of 0)
+ OSPF: advertised from R1 with AD of 110 (O E2) (and metric of 20)
Therefore R3 will choose the path with the lower AD via OSPF But this is a looped path which is received from R3 -> R2 -> R1 -> R3. So when the advertised route from R4 is expired, the looped path is also expired soon and R3 will reinstall the main path from R4. This is the cause of intermittent connectivity. In order to solve this issue, we can lower the AD of iBGP to a value which is lower than 110 so that it is preferred over OSPF-advertised route.
Explanation:
After redistribution, R3 learns about network 10.1.1.0/24 via two paths:
+ Internal BGP (IBGP): advertised from R4 with AD of 200 (and metric of 0)
+ OSPF: advertised from R1 with AD of 110 (O E2) (and metric of 20)
Therefore R3 will choose the path with the lower AD via OSPF But this is a looped path which is received from R3 -> R2 -> R1 -> R3. So when the advertised route from R4 is expired, the looped path is also expired soon and R3 will reinstall the main path from R4. This is the cause of intermittent connectivity. In order to solve this issue, we can lower the AD of iBGP to a value which is lower than 110 so that it is preferred over OSPF-advertised route.