| 主权项 |
1. A method for implementing path protection in multicasting, the method comprising:
establishing, by a head node, a point to multi-point (P2MP) tree spanning from the head node to a plurality of tail nodes, the P2MP tree including additional mid-point nodes, the P2MP tree providing a label switched path (LSP) from the head node to a particular tail node; identifying, by the head node, a first plurality of source-to-leaf (S2L) sub-LSPs for the LSP, the first plurality of S2L sub-LSPs included within the P2MP tree and each S2L sub-LSP spanning over at least one mid-point node; identifying, by the head node, a second plurality of S2L sub-LSPs for the LSP, the second plurality of S2L sub-LSPs included within the P2MP tree and each S2L sub-LSP spanning over at least one mid-point node, each S2L sub-LSP corresponding to a respective S2L sub-LSP in the first plurality, and each S2L sub-LSP in the second plurality and the respective S2L sub-LSP in the first plurality having no overlapping mid-point nodes; setting, by the head node, a first flag of an object in a Resource Reservation Protocol (RSVP) path message to designate the second plurality of S2L sub-LSPs as protecting respective S2L sub-LSPs in the first plurality at a baseline level of protection; setting, by the head node, a second flag of the object in the RSVP path message to designate a subset of S2L sub-LSPs in the second plurality associated with the first flag as protecting respective S2L sub-LSPs in the first plurality at an elevated level of protection, the second flag being different from the first flag and set before the respective S2L sub-LSP in the first plurality has failed to allow carrying of packets for a respective S2L sub-LSP in the first plurality prior to failure of the respective S2L sub-LSP; and transmitting, from the head node to other nodes in the P2MP tree, the RSVP path message. |
