Before You Begin

Before you begin a unified ISSU, complete the tasks in the following sections:

Verify That the Master and Backup Routing Engines Are Running the Same Software Version

To verify that both Routing Engines are running the same version of software, issue the following command:

{master}

user@host> show version invoke-on all-routing-engines

re0:
--------------------------------------------------------------------------
Hostname: host
Model: m320
JUNOS Base OS boot [9.0-20071210.0]
JUNOS Base OS Software Suite [9.0-20071210.0]
JUNOS Kernel Software Suite [9.0-20071210.0]
JUNOS Crypto Software Suite [9.0-20071210.0]
JUNOS Packet Forwarding Engine Support (M/T Common) [9.0-20071210.0]
JUNOS Packet Forwarding Engine Support (M320) [9.0-20071210.0]
JUNOS Online Documentation [9.0-20071210.0]
JUNOS Routing Software Suite [9.0-20071210.0]
re1:
--------------------------------------------------------------------------
Hostname: host
Model: m320
JUNOS Base OS boot [9.0-20071210.0]
JUNOS Base OS Software Suite [9.0-20071210.0]
JUNOS Kernel Software Suite [9.0-20071210.0]
JUNOS Crypto Software Suite [9.0-20071210.0]
JUNOS Packet Forwarding Engine Support (M/T Common) [9.0-20071210.0]
JUNOS Packet Forwarding Engine Support (M320) [9.0-20071210.0]
JUNOS Online Documentation [9.0-20071210.0]
JUNOS Routing Software Suite [9.0-20071210.0]

If both Routing Engines are not running the same software version, issue the request system software add command on the desired Routing Engine so that the software version is the same. For more information, see the Junos OS Installation and Upgrade Guide.

Back Up the Router Software

As a preventive measure in case any problems occur during an upgrade, issue the request system snapshot command on each Routing Engine to back up the system software to the router’s hard disk. The following is an example of issuing the command on the master Routing Engine:

{master}

user@host> request system snapshot

Verifying compatibility of destination media partitions...
Running newfs (220MB) on hard-disk media / partition (ad1s1a)...
Running newfs (24MB) on hard-disk media /config partition (ad1s1e)...
Copying '/dev/ad0s1a' to '/dev/ad1s1a' .. (this may take a few minutes)
Copying '/dev/ad0s1e' to '/dev/ad1s1e' .. (this may take a few minutes)
The following filesystems were archived: / /config

Note: The root file system is backed up to /altroot, and /config is backed up to /altconfig. After you issue the request system snapshot command, the router’s flash and hard disks are identical. You can return to the previous version of the software only by booting the router from removable media. For more information about the request system snapshot command, see the Junos System Basics Configuration Guide.

Verify That Graceful Routing Engine Switchover and Nonstop Active Routing Are Configured

Before you begin a unified ISSU, ensure that graceful Routing Engine switchover and nonstop active routing are configured on your router.

To verify graceful Routing Engine switchover is configured, on the backup Routing Engine (re1) issue the show system switchover command. The output should be similar to the following example. The Graceful switchover field state must be On.
{backup}

user@host> show system switchover
```
Graceful switchover: On
Configuration database: Ready
Kernel database: Ready
Peer state: Steady State
```

To verify nonstop active routing is configured, on the master Routing Engine (re0) issue the show task replication command. The output should be similar to the following example.

{master}

user@host> show task replication

        Stateful Replication: Enabled
        RE mode: Master

    Protocol                Synchronization Status
    OSPF                    Complete              
    IS-IS                   Complete

If graceful Routing Engine switchover and nonstop active routing are not configured, complete the following steps:

On the master Routing Engine (re0), enable graceful Routing Engine switchover. Include the graceful-switchover statement at the [edit chassis redundancy] hierarchy level.
On the master Routing Engine, enable nonstop active routing. Include the commit synchronize statement at the [edit system] hierarchy level and the nonstop-routing statement at the [edit routing-options] hierarchy level.
On the master Router Engine, issue the commit command.
The system provides the following confirmation that the master and backup Routing Engines are synchronized:
```
re0: 
configuration check succeeds
re1: 
commit complete
re0: 
commit complete
```

Before You Begin

Verify That the Master and Backup Routing Engines Are Running the Same Software Version

Back Up the Router Software

Verify That Graceful Routing Engine Switchover and Nonstop Active Routing Are Configured

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