Fast-reroute procedures for multi-point to multi-point MPLS tunnels

This paper proposes fast reroute extensions to RSVP-TE in order to support the protection of multipoint to multipoint (MP2MP) MPLS TE-tunnels. To protect an element (link or node) of a primary MP2MP TE-tunnel, we propose to use an MP2MP bypass TE-tunnel connecting a set of nodes around the protected element. During failure the primary MP2MP TE-tunnel is encapsulated into the MP2MP bypass TE-tunnel which calls for defining a new type of MPLS hierarchy, the multipoint to multipoint hierarchy. The node of the primary MP2MP TE-tunnel upstream to the protected element, called the upstream protecting node (UPN), selects the MP2MP bypass TE-tunnel to be used for the protection. By extending the point to multipoint MPLS hierarchy, which relies on the upstream label assignment, we discuss several extensions scenarios depending on the number of leaves of a bypass TE-tunnel and on the number of UPNs per bypass tunnel. The scalability/bandwidth-consumption tradeoff between these schemes is analyzed by means of simulations. The proposed method can be efficiently used for the protection of point-to-point and point-to-multipoint TE-tunnels as well, as such tunnels are actually particular cases of MP2MP TE-tunnels.