Alcatel-Lucent 7750 SR OS - Manual (Page 32)

Configuring IP Router Parameters
Page 32 7750 SR OS Router Configuration Guide
• LDP is used to create the MPLS full mesh between the 6PE routers and the IPv4 addresses
that are embedded in the next-hop field are reachable by LDP LSPs. The ingress 6PE
router uses the LDP LSPs to reach remote 6PE routers.
6PE Data Plane Support
The ingress 6PE router can push two MPLS labels to send the packets to the egress 6PE router. The
top label is an LDP label used to reach the egress 6PE router. The bottom label is advertised in MP-
BGP by the remote 6PE router. Typically, the IPv6 explicit null (value 2) label is used but an
arbitrary value can be used when the remote 6PE router is from a vendor other than Alcatel-
Lucent.
The egress 6PE router pops the top LDP tunnel label. It sees the IPv6 explicit null label, which
indicates an IPv6 packet is encapsulated. It also pops the IPv6 explicit null label and performs an
IPv6 route lookup to find out the next hop for the IPv6 packet.