Patent ID: 7336648

Claim:
An explicit routing method in a label switching system, including explicitly specifying, when setting a label switched path (LSP) on the basis of an explicit route specified, a port or a port group of an egress node, and a port or a port group of a relay node, the explicit routing method comprising: a step of specifying a port or a port group of the egress node by setting an IP address corresponding to the port or the port group of the egress node in a final ER-HOP-TLV field in ER-TLVs in Label Request Message of CR-LDP (Constraint-Based LSP setup using LDP (Label Distribution Protocol)); and a step of specifying a port or a port group of the relay node by setting an IP address corresponding to the port or the port group of the relay node in an intermediate ER-HOP-TLV field in ER-TLVs in Label Request Message of the CR-LDP.