Enabling Interarea Traffic Engineering

The Junos OS can signal a contiguous traffic-engineered LSP across multiple OSPF areas. The LSP signaling must be done using either nesting or contiguous signaling, as described in RFC 4206, Label-Switched Paths (LSP) Hierarchy with Generalized Multi-Protocol Label Switching (GMPLS) Traffic Engineering (TE). However, contiguous signaling support is limited to just basic signaling. Reoptimization is not supported with contiguous signaling.

The following describes some of the interarea traffic engineering features:

Interarea traffic engineering can be enabled when the loose-hop area border routers (ABRs) are configured on the ingress router using CSPF for the Explicit Route Object (ERO) calculation within an OSPF area. ERO expansion is completed on the ABRs.
Interarea traffic engineering can be enabled when CSPF is enabled, but without ABRs specified in the LSP configuration on the ingress router (ABRs can be automatically designated).
Differentiated Services (DiffServ) traffic engineering is supported as long as the class type mappings are uniform across multiple areas.

To enable interarea traffic engineering, include the expand-loose-hop statement in the configuration for each LSP transit router:

expand-loose-hop;

You can include this statement at the following hierarchy levels:

[edit protocols mpls]
[edit logical-systems logical-system-name protocols mpls]