4A0-105: Nokia Virtual Private LAN Services

In an N-node full mesh, each router originates one primary RSVP-TE LSP to every other router, giving N-1 primary LSPs per node; with 5 PEs, PE-5 originates 4 primary LSPs. RFC 4090 specifies that with the one-to-one backup (detour) method of MPLS Fast Reroute, every LSR along a protected LSP except the egress acts as a point of local repair (PLR) and signals its own dedicated detour LSP for the resource it protects; because the ingress node is always the PLR protecting its own first outgoing hop, PE-5 additionally originates one detour LSP per primary LSP it heads, so the total number of LSPs originating from PE-5 is 2 x (5-1) = 8.