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Problem Establishing a GRE Tunnel Checklist



Description: This checklist provides the links and commands for troubleshooting a case study about a problem establishing a Generalized Multiprotocol Label Switching (GMPLS) label-switched path (LSP). Specifically, the configuration of the data channel is incorrect because the configuration includes different interface types at both ends of the tunnel. The principles and solution used in this case study also apply to control channel configuration.

The checklist includes the links to a brief summary of GRE tunnels within the context of GMPLS, an example network scenario, and more detailed information about the commands used to troubleshoot and resolve the problem.

The troubleshooting process described in this case study should not be followed rigidly; it is a basis from which you can develop your own process to suit your particular situation. (See Table 1


Table 1: Problem Establishing a GRE Tunnel Checklist


Command or Action

Troubleshooting GMPLS and GRE Tunnel 


show mpls lsp

show rsvp session


The cause of the problem with the GMPLS LSP is the configuration of different interface types at both ends of the GMPLS data channel.

Troubleshooting Commands

show mpls lsp extensive

show rsvp session detail

show link-management peer

show link-management te-link

show configuration protocols mpls

monitor start filename

show log filename


Configure both ends of the data channel with the same switching type.

show configuration protocols link-management

show mpls lsp

show link-management te-link


Both ends of a GMPLS data must be the same encapsulation or interface type.

Router Configurations

show configuration | no-more