BGP Attributes for Loop Prevention
Question
Which three BGP attributes are used for loop prevention? (Choose three.)
Answers
Explanations
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A. B. C. D. E.ABD
The Border Gateway Protocol (BGP) is a routing protocol used to exchange routing information between different autonomous systems (ASes) in the Internet. To ensure loop prevention in BGP, the following attributes are commonly used:
AS Path: The AS Path attribute specifies the sequence of ASes that a route has traversed to reach a destination network. Each AS that the route passes through is added to the AS Path attribute in the order that it was traversed. BGP routers use this attribute to avoid routing loops by discarding routes that contain their own AS number in the AS Path.
Originator ID: The Originator ID attribute is used in BGP route reflection to prevent routing loops. When a BGP router reflects a route to another router in the same AS, it adds its own router ID to the Originator ID attribute. If the same route is received from a different path, the router will compare the Originator ID with its own ID and discard the route if they match.
Cluster List: The Cluster List attribute is also used in BGP route reflection to prevent routing loops. When a BGP router reflects a route to another router in the same cluster, it adds the cluster ID to the Cluster List attribute. If the same route is received from a different cluster, the router will compare the Cluster List with its own list and discard the route if there is a match.
Therefore, the correct answers to the question are A (AS Path), B (originator ID), and D (cluster list). The next hop and origin attributes are not used for loop prevention in BGP.
