Passport 4400 Global Circuit Manager (GCM)

The global circuit manager (GCM) monitors and controls the use of available ports on the base module and the logical links between Passport 4400 nodes. For example, it monitors whether links are up or down. The GCM does not store any protocol information or signaling, such as dial phone numbers for ISDN, which allows the GCM to transparently manage different interface types.

The following terms describe the functions of the GCM for each node type:

• Primary Port: the port on the Passport 4400 base module that the GCM selects to carry a PANL-DTE netlink (the primary netlink).
• Primary Netlink: the PANL-DTE netlink established on the primary port. This netlink is automatically configured after a default reset. See Configure Connections to the Passport Network for more information.
• Backup Port: the port on the Passport 4400 base module that the GCM reserves for backup use. The designation of a backup port is optional.
• Backup Netlink: a PANL-DTE netlink established on the backup port.

By default, each Passport 4400 is configured with a PANL-DTE netlink to a higher-level Passport node. This netlink is called the primary netlink. Using the GCM, it is possible to create and use an additional PANL-DTE netlink (a backup netlink) if the primary netlink fails.

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