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Link-Local Next Hops in MP-BGP Packets

When the router has an external directly connected (non-multihop) BGP peer, the router advertises two next hops. It advertises the global next hop and a next hop with a link-local address. The link-local next hop is advertised even when the router has been configured with the next-hop self feature. Advertising the link-local next hop enables the configuration of single-hop EBGP sessions for IPv6 next hops.

For all other types of peers, the router advertises only the global BGP IPv6 next hop.

You can overwrite the global and link-local IPv6 next-hop addresses by configuring and applying a route map that sets the addresses. The set ipv6 next-hop clause in the route map can specify a global address, a link-local address, or both for the next hop.

However, a neighbor outbound route map that adds a link-local IPv6 address for peers where the router should not advertise a link-local next hop is considered an invalid configuration.

The router accepts both global and link-local BGP IPv6 next-hop addresses received from its BGP IPv6 peers. As a consequence, when advertising a route to an internal peer, the router can modify the network address of the next-hop field by removing the link-local IPv6 address of the next hop.

For static BGP peers, the JUNOSe software does not support the use of link-local addresses when you configure BGP peers. You cannot configure the local interface for a neighbor that has been configured with a link-local address. Although you can configure a neighbor with a link-local address, a BGP session to that peer over TCP IPv6 does not come up.

For dynamic BGP peers, an E-series router can accept incoming TCP sessions with the link-local address as the source address. However, the BGP peering does not come up for such a connection.

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