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    Understanding the Unified ISSU Process on the TX Matrix Plus Router and on the TX Matrix Plus Router with 3D SIBs

    This topic describes the processes that take place on a TX Matrix Plus router and the routers acting as connected line-card chassis (LCCs) as well as on a TX Matrix Plus router with 3D SIBs and its connected routers acting as LCCs.

    Note: A routing matrix is a multichassis architecture. In this topic, the term TX Matrix Plus router denotes a routing matrix based on a Juniper Networks TX Matrix Plus router and its connected T1600 LCCs. The term TX Matrix Plus router with 3D SIBs denotes a routing matrix based on a Juniper Networks TX Matrix Plus router and its connected T1600 and T4000 LCCs.

    Each router has dual Routing Engines.

    Unified ISSU Process on the TX Matrix Plus Router and on the TX Matrix Plus Router with 3D SIBs

    After you use the request system software in-service-upgrade command, the following process occurs:

    1. The management process (mgd) on the master Routing Engine of the TX Matrix Plus router (global master) checks the current configuration.

      Checks are made for the following:

      • Disk space is available for the /var file system on both Routing Engines.
      • The configuration is supported by a unified ISSU.
      • The PICs are supported by a unified ISSU.
      • Graceful Routing Engine switchover is enabled.
      • Nonstop active routing is enabled.
    2. After successful validation of the configuration, the management process copies the new image to the backup Routing Engines on the TX Matrix Plus router and the connected T1600 router LCCs.
    3. The kernel synchronization process (ksyncd) on the backup Routing Engines synchronizes the kernels on the backup Routing Engines with the kernels on the master Routing Engines.
    4. The global backup Routing Engine is upgraded with the new software. Next the global backup Routing Engine is rebooted. Then the global backup Routing Engine synchronizes the configuration and kernel state from the global master Routing Engine.
    5. The unified ISSU control moves from the management process to the chassis process (chassisd). The chassis process informs the various software processes (such as rpd, apsd, bfdd, and so on) about the unified ISSU and waits for responses from them.
    6. After receiving messages from the software processes indicating that the processes are ready for unified ISSU, the chassis process on the global master Routing Engine sends messages to the chassis process on the routers to start the unified ISSU.
    7. The chassis process on the routers sends ISSU_PREPARE messages to the field-replaceable units (FRUs), such as FPCs and intelligent PICs.
    8. After receiving an ISSU_PREPARE message, the Packet Forwarding Engines save the current state information and download the new software image from the backup Routing Engines. Next, each Packet Forwarding Engine sends ISSU_READY messages to the chassis process. You can display the unified ISSU process messages by using the show log messages command.
    9. After receiving an ISSU_READY message from the Packet Forwarding Engines, the chassis process sends an ISSU_REBOOT message to the FRUs. While the upgrade is in progress, the FRUs keep sending ISSU_IN_PROGRESS messages to the chassis process. The chassis process on each router, in turn, sends an ISSU_IN_PROGRESS message to the chassis process on the global master Routing Engine.
    10. After the unified ISSU reboot, the Packet Forwarding Engines restore the saved state information and connect back to the router. Then the chassis process on each router sends an ISSU_READY message to the chassis process on the global master Routing Engine. The CM_MSG_READY message (this message is sent from the LCC chassisd to the global master’s chassisd) indicates that the unified ISSU is complete on the FRUs.
    11. The unified ISSU control moves back to the management process on the global master Routing Engine.
    12. The management process initiates a Routing Engine switchover on the master Routing Engines.
    13. Routing Engine switchover occurs on the TX Matrix Plus router and all the connected LCCs.
    14. After the switchover, the FRUs connect to the new master Routing Engines, and the chassis manager and Packet Forwarding Engine manager on the connected LCC FRUs connect to the new master Routing Engines on the connected LCCs.
    15. The management process on the global master Routing Engine initiates the upgrade process on the Routing Engines that were previously the masters on the connected T1600 router LCCs. (This step is skipped if you have specified the no-old-master-upgrade option in the request system software in-service-upgrade command.)
    16. After the Routing Engines that were previously the masters on the connected T1600 router LCCs are upgraded, the management process initiates the upgrade of the Routing Engine that was previously the global master on the TX Matrix Plus router and all its connected LCCs.
    17. After a successful unified ISSU, the TX Matrix Plus global Routing Engine (re1) that was previously the master and is now the backup and the LCC Routing Engines that were previously the masters and are now the backups are rebooted if you specified the reboot option in the request system software in-service-upgrade command.

    Modified: 2015-07-27