Cisco Cisco IOS Software Release 12.0(22)S

This document describes the Multiprotocol Label Switching (MPLS) traffic engineering (TE) Interarea 
Tunnels feature in Cisco IOS Release 12.0(22)S. The document contains the following sections:

The MPLS TE Interarea Tunnels feature allows you to establish MPLS TE tunnels that span multiple 
Interior Gateway Protocol (IGP) areas and levels, removing the restriction that had required the tunnel 
head-end and tail-end routers both be in the same area. The IGP can be either Intermediate 
System-to-Intermediate System (IS-IS) or Open Shortest Path First (OSPF). 

To configure an interarea tunnel, you specify on the head-end router a loosely routed explicit path for 
the tunnel label switched path (LSP) that identifies each area border router (ABR) the LSP should 
traverse using the next-address loose command. The head-end router and the ABRs along the specified 
explicit path expand the loose hops, each computing the path segment to the next ABR or tunnel 
destination. 

12.0(19)ST1

This feature was introduced. 

12.0(21)ST

Support for the Cisco GSR 12000 series platform was added. 

12.0(22)S

Support for the Cisco 10000 series edge services routers (ESRs) was 
added.