You are establishing a new BGP session to an EBGP peer using loopback addresses. In addition to your general EBGP settings, which BGP feature must be…

By default, External BGP (EBGP) sessions are established with a Time-to-Live (TTL) value of 1, operating under the assumption that the peering routers are directly connected on the same physical subnet. When establishing an EBGP session using loopback addresses, the IP packets must traverse at least one internal hop (from the physical receiving interface to the logical loopback interface). This requires a TTL greater than 1. The multihop feature must be configured to increase the TTL value of the BGP packets, allowing the EBGP session to establish successfully over the loopback interfaces.

B. Multipath is a feature used for load balancing traffic across multiple equal-cost BGP paths, not for establishing BGP sessions.

C. Damping is a route stability mechanism used to suppress flapping routes and prevent network instability, which is unrelated to session establishment.

D. Passive mode prevents the local router from initiating the TCP connection for BGP, which does not resolve the TTL limitation required for loopback peering.

- Juniper Networks, "Junos OS Routing Protocols Library," Release 21.4, Chapter: BGP Configuration, Section: ebgp-multihop.

- Juniper Networks, "BGP User Guide," Section: EBGP Multihop Configuration and TTL requirements.