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Replacing the T640 Host Subsystem Components
Taking the T640 Host Subsystem Offline
The host subsystem is taken offline and brought online as a unit. Before you replace a control board or Routing Engine, you must take the host subsystem offline.
Normally, if two host subsystems are installed in the T640 router, RE0
functions as the master and RE1
functions as the backup. You can remove the backup host subsystem
(or either of its components) without interrupting the functioning
of the router. If you take the master host subsystem offline, the
backup host subsystem becomes the master (the router might reboot,
depending on your configuration). If the router has only one host
subsystem, taking the host subsystem offline causes the router to
shut down.
Table 1 explains the effect of taking the host subsystem offline.
Table 1: Effect of Taking the Host Subsystem Offline
Type of Host Subsystem | Effect of Taking the Host Subsystem Offline |
---|---|
Nonredundant host subsystem | The router shuts down. |
Backup host subsystem | The functioning of the router is not interrupted. The backup host subsystem is hot-removable and hot-insertable. |
Master host subsystem | The backup host subsystem becomes the master. The backup Routing Engine assumes Routing Engine functions. The master host subsystem is hot-pluggable. Removal or failure of the master Routing Engine affects forwarding and routing based on the high availability configuration:
|
Router performance might change if the backup Routing Engine's configuration differs from the former master's configuration. For the most predictable performance, configure the two Routing Engines identically, except for parameters unique to each Routing Engine.
For information about configuring graceful Routing Engine switchover, graceful restart, and nonstop active routing, see the Junos OS High Availability Library for Routing Devices.
The first supported release for graceful Routing Engine switchover and nonstop active routing on the T640 router is Junos OS Release 7.0 and Junos OS Release 8.4, respectively. Graceful restart software requirements depend on the routing protocols configured on the router. For the minimum software requirements for graceful restart, see the Junos OS High Availability Library for Routing Devices.
To take a host subsystem offline:
- Determine whether the host subsystem is functioning as
the master or as the backup, using one of the two following methods:
Check the Routing Engine LEDs on the craft interface. If the green
MASTER
LED is lit, the corresponding host subsystem is functioning as the master.Issue the following CLI command. The master Routing Engine is designated Master in the Current state field:
user@host> show chassis routing-engine
Routing Engine status: Slot 0: Current state Master Election priority Master (default) Temperature 34 degrees C / 93 degrees F DRAM 2048 Mbytes CPU utilization: User 0 percent Background 0 percent Kernel 1 percent Interrupt 0 percent Idle 99 percent Start time 2002-01-22 05:21:31 UTC Uptime 10 days, 16 hours, 4 minutes, 52 seconds Load averages: 1 minute 5 minute 15 minute 0.00 0.00 0.00 Routing Engine status: Slot 1: Current state Empty
- If the host subsystem is functioning as the master, switch
it to backup using the CLI command:
user@host> request chassis routing-engine master switch
- To halt the router:
user@host> request system halt
Wait until a message appears on the console confirming that the operating system has halted.
The command shuts down the Routing Engine cleanly, so its state information is preserved. For more information about the command, see request system halt.
Note The SIBs might continue forwarding traffic for approximately 5 minutes after the request system halt command has been issued.
- On the console or other management device connected to
the other Routing Engine, enter CLI operational mode and issue the
following command.
user@host> request chassis cb offline slot n
n is 0 or 1 for the slot number of the host subsystem being taken offline.
- Verify that the control board is offline:
user@host> show chassis environment cb