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Cisco Auto-Tunnels Overview

NorthStar Planner supports the modeling of Cisco's auto-tunnels, including both mesh group auto-tunnels and backup auto-tunnels.

Use these procedures if you have Cisco auto-tunnels configured in your network and you want to model them in the NorthStar Planner tool.

If you wish to perform this task, you should have a set of router configuration files with Cisco auto-tunnels configured.

The mesh group auto-tunnels feature automates the configuration of a mesh of primary MPLS tunnels that share the same attributes. This feature can be used when creating a set of fully-meshed MPLS tunnels, or when adding a new router to a meshed group. Configuration of mesh group auto-tunnels involves building a template (via the interface auto-template statement) that identifies the attributes of the primary tunnels to be created as well as the tunnel destinations (by using an access-list).

Cisco's backup auto-tunnels feature provides the capability to automatically build backup tunnels for the primary tunnel. These backup tunnels are setup using NHOP or NNHOP protection. Configuration of backup auto-tunnels involves just one required statement (mpls traffic-eng auto-tunnel backup). For detailed background information on how auto-tunnels work, as well as on how to configure auto-tunnels, see the appropriate Cisco documentation.

NorthStar Planner models auto-tunnels in the following way:

  • Configuration Import: Parse the configuration file to look for auto-tunnel related configuration statements and store the auto-tunnel settings into a file called atconfig.runcode.

  • Auto-tunnels Creation: From the atconfig.runcode file, generate the corresponding auto-tunnels in the network spec.

  • Tunnel Path Data Collection and Import: The output of the show mpls traffic-eng tunnels command may be captured into a file for each router and then imported into the tool. The imported tunnel paths provide the actual network view of the tunnel paths, and so are used to replace the tunnel paths and tunnel IDs generated by the tool.

  • Verification: The tool provides three types of reports (Report Manager's Tunnel layer, Auto-tunnel folder) to help the user to verify Cisco's auto-tunnels. The Discrepancy Report lists the modeled tunnels that are not present in the collected tunnels. The Protection Report shows each interface that is protected by an auto-backup tunnel. The Overlap Report shows interfaces that are protected by an autobackup tunnel and manual backup tunnel.

  • Design (optional): Analysis of the reports may reveal that certain mesh group primary auto-tunnels and/or backup auto-tunnels are missing from the actual router environment. In such cases, the tool may be used to design for these missing tunnels.