Technical Documentation

Configuring the JUNOS Software the First Time on a Router with Dual Routing Engines

If a router has dual Routing Engines, you must initially configure each router independently. The sequence is irrelevant.

Configure the hostnames and addresses of the two Routing Engines using configuration groups at the [edit groups] hierarchy level. Use the reserved configuration group re0 for the Routing Engine in slot 0 and re1 for the Routing Engine in slot 1 to define properties specific to the individual Routing Engines. Configuring re0 and re1 groups enables both Routing Engines to use the same configuration file.

Use the apply-groups statement to reproduce the configuration group information in the main part of the configuration.

The commit synchronize command commits the same configuration on both Routing Engines. The command makes the active or applied configuration the same for both Routing Engines with the exception of the groups, re0 being applied to only RE0 and re1 being applied only to RE1. If you do not synchronize the configurations between two Routing Engines and one of them fails, the router may not forward traffic correctly, because the backup Routing Engine may have a different configuration.

To initially configure a router with dual Routing Engines, follow these steps:

  1. Go to Configuring the JUNOS Software the First Time on a Router with a Single Routing Engine and follow Step 1 through Step 5 to initially configure the backup Routing Engine.
  2. Instead of Step 6 and Step 8 in Configuring the JUNOS Software the First Time on a Router with a Single Routing Engine, configure a hostname for each Routing Engine and an IP address for each management Ethernet interface fxp0 or em0 as follows:
    • For all routers other than a TX Matrix Plus router or a T1600 standalone router not in a routing matrix, issue the following commands:
      [edit]root@# edit groups [edit groups]root@# set re0 system host-name router1 root@# set re0 interfaces fxp0 unit 0 family inet address 10.10.10.1/24 root@# set re1 system host-name router2 root@# set re1 interfaces fxp0 unit 0 family inet address 10.10.10.2/24
    • For a TX Matrix Plus router and T1600 routers in a routing matrix, issue the following commands:
      [edit]root@# edit groups [edit groups]root@# set re0 system host-name router1 root@# set re0 interfaces em0 unit 0 family inet address 10.10.10.1/24 root@# set re1 system host-name router2 root@# set re1 interfaces em0 unit 0 family inet address 10.10.10.2/24
  3. Configure the router’s domain name:
    [edit]root@# set system domain-name domain-name
  4. Set the loopback interface address for each Routing Engine.
    [edit groups]root@# set re0 interfaces lo0 unit 0 family inet address 2.2.2.1/32root@# set re1 interfaces lo0 unit 0 family inet address 2.2.2.2/32
  5. Configure the apply-groups statement to reproduce the configuration group information to the main part of the configuration.
    [edit groups]root@# top[edit]root@# set apply-groups [re0 re1]
  6. Configure Routing Engine redundancy:
    [edit]root@# set chassis redundancy routing-engine 0 masterroot@# set chassis redundancy routing-engine 1 backuproot@# set chassis redundancy routing-engine graceful-switchover
  7. Save the configuration change on both Routing Engines:
    [edit]user@host> commit synchronizeroot@#
  8. Continue with Step 9 through Step 12 in Configuring the JUNOS Software the First Time on a Router with a Single Routing Engine.
  9. After you have installed the new software and are satisfied that it is successfully running, issue the request system snapshot command to back up the new software on both master and backup Routing Engines.
    {master}user@host> request system snapshot

    The root file system is backed up to /altroot, and /config is backed up to /altconfig. The root and /config file systems are on the router’s CompactFlash card, and the /altroot and /altconfig file systems are on the router’s hard disk.

    Note: After you issue the request system snapshot command, you cannot return to the previous version of the software, because the running copy and backup copy of the software are identical.


Published: 2010-04-26