17-122 Riverstone Networks RS Switch Router User Guide Release 8.0
Traffic Engineering MPLS Configuration

Advertising IGP Shortcuts

IGP shortcuts need to be advertised so that other routers in the autonomous system can calculate paths that use the LSP.
You advertise these shortcuts with the isis add label-switched-path command for IS-IS networks and with
the ospf add label-switched-path command for OSPF networks.
Note Each LSP is advertised as a unidirectional, point-to-point link. OSPF and IS-IS
both verify that there is a bidirectional connection between nodes before using an
advertised link. Therefore, you need to configure two LSPs, one in each direction,
for paths between two LSRs that will be advertised in IS-IS or OSPF autonomous
systems.
The LSP is advertised as a unidirectional, point-to-point link. The advertisement contains:
•the source address of the LSP (usually the address of the local router)
•the destination address of the LSP (usually the address of the egress router)
•a metric value
The metric value is an optional parameter configured for the LSP with the mpls create|set
label-switched-path command. If no metric value is configured for the LSP with the isis, ospf, or mpls
commands, then a metric value of 1 is used.