Nokia Border Gateway Protocol Fundamentals for Services 4A0-114 Question # 10 Topic 2 Discussion
4A0-114 Exam Topic 2 Question 10 Discussion:
Question #: 10
Topic #: 2
Click the exhibit.
Routers RR1 and RR2 are route reflectors with the same Cluster-ID. How does router RA treat the updates for prefix 192.168.1.0/27 received from routers RR1 and RR2?
A.
Router RA prefers the update received from router RR1.
B.
Router RA prefers the update received from router RR2.
C.
Router RA flags both updates as invalid.
D.
Router RA accepts both updates and flags them as used.
Route Reflector (RR) Basics: In a BGP network, route reflectors help reduce the need for a full mesh of iBGP sessions. Each route reflector assigns a cluster ID to identify the cluster it belongs to and avoid routing loops.
Cluster-ID: When multiple route reflectors have the same cluster ID, a router receiving routes from these reflectors will use the cluster ID to identify if the routes have been advertised by the same cluster.
Duplicate Routes: If a route is received from different route reflectors with the same cluster ID, the receiving router (RA) will detect this as a duplicate advertisement from the same cluster.
Invalid Route Handling: BGP protocol dictates that routes received from the same cluster ID will be flagged as invalid to prevent potential routing loops.
Conclusion: Router RA flags both updates for prefix 192.168.1.0/27 received from RR1 and RR2 as invalid because they have the same cluster ID.
References:
Nokia Border Gateway Protocol Fundamentals
RFC 4456 - BGP Route Reflection: An Alternative to Full Mesh iBGP
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