Juniper Enterprise Routing and Switching - Professional (JNCIP-ENT) JN0-650 Question # 21 Topic 3 Discussion
JN0-650 Exam Topic 3 Question 21 Discussion:
Question #: 21
Topic #: 3
Your router is discarding an EBGP route because the next hop is not directly connected. Which BGP configuration would you use to override this behavior?
In External BGP (EBGP), there is a default safety mechanism that requires the peer ' s next hop to be on a directly connected network.
TTL Constraint: By default, EBGP packets are sent with a Time-to-Live (TTL) value of 1. If the next hop is not directly connected (e.g., when peering via loopback interfaces or across a multi-hop path), the packet will expire before reaching the destination, causing the route to be discarded or the session to fail.
The Multihop Solution (Option B): To override this behavior, you must configure the multihop statement under the BGP neighbor or group hierarchy. This allows the BGP session to establish by increasing the TTL (typically to 64 or a user-defined value) and bypasses the " directly connected " check.
Incorrect Options: Option A (accept-remote-nexthop) is used in internal BGP or specific routing-instance scenarios to resolve next hops that aren ' t in the local routing table, but it doesn ' t solve the EBGP TTL/direct-connection requirement. Option C (advertise-inactive) allows BGP to advertise routes that are not the best path in the routing table, which is irrelevant to next-hop reachability. Option D (multipath) is used for load-sharing across multiple paths.
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