US 6,982,977 B2 | ||
Label switched routing system and method | ||
Constantin Viorel Marian, Nepean (Canada); and Dan Oprea, Kanata (Canada) | ||
Assigned to Tropic Networks Inc., Kanata (Canada) | ||
Filed on Oct. 19, 2001, as Appl. No. 9/981,887. | ||
Prior Publication US 2003/0081589 A1, May 01, 2003 | ||
Int. Cl. H04L 12/56 (2006.01); H04L 12/28 (2006.01) |
U.S. Cl. 370—392 | 21 Claims |
1. A packet routing/switching method comprising:
defining a hierarchical plurality of label switched paths (LSP)/forwarding adjacency-label switched paths (FA-LSP) through
a network of nodes from a lowest (least-nested) level to a highest (most-nested) level, each LSP/FA-LSP comprising a respective
sequence of nodes comprising at least a source node and a destination node and possibly one or more transit nodes;
to route/switch a packet flow from a first source node of said network of nodes to a first destination node of said network
of nodes:
a) maintaining at the first node a mapping between the packet flow and a first LSP of the hierarchical plurality of LSP/FA-LSPs
defined between the first source node and the first destination node;
b) at the first source node, for each packet of said packet flow, adding to the packet label switched routing information
comprising an LSP label identifying the first LSP and sending the packet to subsequent node(s) in the sequence of nodes defined
for the first LSP;
c) at each node to which the packet is routed/switched other than said first source node:
i) if the node is a source node of a higher level FA-LSP than the LSP/FA-LSP identified by the LSP label of the packet, changing
the LSP label in the label switched routing information to indicate the source node of the higher level FA-LSP, and including
in the label switched routing information hierarchy information in respect of all lower level LSP/FALSPs in the hierarchy
leading up to the higher level FA-LSP and forwarding the packet to the next node in the sequence of nodes defined for the
higher level FA-LSP;
ii) if the node is only a transit node, forwarding the packet to the next node in the sequence of nodes defined for the LSP/FALSP
identified by the LSP label;
iii) if the node is a destination node of a higher level FA-LSP, changing the LSP label in the label switched routing information
to indicate the source node of the next lower level LSP/FA-LSP indicated by the hierarchy information, and changing the hierarchy
information to include only hierarchy information in respect of LSP/FA-LSPs in the hierarchy leading up to but not including
the next lower level LSP/FA-LSP, and forwarding the packet to the next node in the sequence of nodes defined for the next
lower level LSP/FA-LSP.
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