TX Matrix Component Redundancy

• TX-SIBs—The TX Matrix router has five TX-SIBs. Each TX-SIB and the T640-SIBs connected to it represent a data switching plane that spans the TX Matrix router and all T640 routers in the routing matrix. One of the five TX-SIBs—usually TX-SIB-0—acts as a backup to the remaining four TX-SIBs. If a TX-SIB or T640-SIB fails, the backup data switching plane becomes active and traffic forwarding continues without any degradation. When the failed component is replaced, the data switching plane in which it resides becomes the new backup. If the failed component is not replaced, and a TX-SIB or T640-SIB in an active data switching plane fails, only that component is taken offline.
• Host subsystem—The host subsystem consists of a Routing Engine functioning together with a TX-CB. The TX Matrix router can have one or two host subsystems. If two host subsystems are installed, one functions as the master and the other functions as the backup. If the master host subsystem (or either of its components) fails, the backup can take over as the master. To operate, each host subsystem requires a Routing Engine installed in an adjacent slot to a TX-CB.

  If the Routing Engines are configured for graceful switchover, the backup Routing Engine automatically synchronizes its configuration and state with the master Routing Engine. Any update to the master Routing Engine state is replicated on the backup Routing Engine. If the backup Routing Engine assumes mastership, packet forwarding continues through the TX Matrix router without interruption. For more information about graceful switchover, see the Junos OS High Availability Configuration Guide .

  Note: We recommend that you run Junos OS Release 7.3 or later on the TX Matrix router to support graceful switchover.

• TX-CIPs—The TX Matrix router has two TX-CIPs. Each TX-CIP provides the ports for its corresponding host subsystem (Routing Engine and TX-CB) in the TX Matrix router and the control plane connections to the Control Boards (T-CBs) in up to four T640 routers.

  If the master TX-CIP fails, the backup TX-CIP provides redundant connections to the active host subsystem in the TX Matrix router and the active T-CBs in the T640 routers. In this case, the Routing Engines in the TX Matrix router and T640 routers do not perform a switchover to their backups.

• Power supplies—The TX Matrix router has two power supplies, which share the load evenly. If one power supply fails, the other power supply can provide full power to the TX Matrix router indefinitely.
• Cooling system—The cooling system has redundant components, which are controlled by the host subsystem. If one of the fans fails, the host subsystem increases the speed of the remaining fans to provide sufficient cooling for the TX Matrix router indefinitely.