Which type of BGP attribute does a route reflector attach to routes learned from iBGP peers that allows them to be accepted by other iBGP peers, thereby eliminating the need for a full-mesh BGP…

Question

Options

• Awell-known mandatory
• Boptional transitive
• Cwell-known discretionary
• Doptional non transitive

• A
  6% (2)
• C
  3% (1)
• D
  91% (31)

Explanation

Route reflectors (RRs) in BGP add two specific attributes to routes they reflect from iBGP peers: ORIGINATOR_ID and CLUSTER_LIST. Both are classified as optional non-transitive attributes. ORIGINATOR_ID (type code 9) carries the Router-ID of the originating iBGP speaker, preventing routing loops by allowing a router to discard routes it originally sent. CLUSTER_LIST (type code 10) is a list of cluster IDs that the route has traversed, also used for loop prevention across multiple route reflector clusters. These attributes are 'optional' because non-route-reflector routers do not need to understand them, and 'non-transitive' because they are not forwarded to external BGP (eBGP) peers - they are only meaningful within the iBGP domain. By attaching these attributes, a route reflector can safely reflect iBGP-learned routes to other iBGP peers, eliminating the full-mesh requirement. Well-known mandatory (Option A) attributes like AS_PATH must be recognized by all BGP implementations. Optional transitive (Option B) attributes like COMMUNITY are passed to eBGP peers. Well-known discretionary (Option C) attributes like LOCAL_PREF must be recognized but need not be included in every update.

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