Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

Navigation
Guide That Contains This Content
[+] Expand All
[-] Collapse All

    Understanding the Unified ISSU Process on the TX Matrix Router

    This topic describes the processes that take place on a TX Matrix router when you initiate a unified in-service software upgrade (ISSU).

    Unified ISSU Process on the TX Matrix Router

    This section describes the processes that take place on a TX Matrix router and the routers acting as connected line-card chassis (LCCs).

    Note: A routing matrix is a multichassis architecture that consists of a TX Matrix router and from one to four T640 routers. From the perspective of the user interface, the routing matrix appears as a single router. The TX Matrix router controls all the T640 routers in the routing matrix.

    Each router has dual Routing Engines.

    After you use the request system software in-service-upgrade command on a TX Matrix router, the following process occurs:

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

      Checks are made for the following:

      • Disk space is available for the /var file system on all 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 router and the T640 routers.
    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 LCC backup Routing Engines are upgraded and rebooted. Then the LCC backup Routing Engines connect with the upgraded global backup Routing Engine and synchronize the configuration and kernel state.
    6. 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.
    7. 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 routing nodes to start the unified ISSU.
    8. The chassis process on the routing nodes sends ISSU_PREPARE messages to the field-replaceable units (FRUs), such as FPCs and intelligent PICs.
    9. 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.
    10. 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 on the routing nodes. The chassis process on each routing node, in turn, sends an ISSU_IN_PROGRESS message to the chassis process on the global master Routing Engine.

      Note: The Packet Forwarding Engine reboots that occur during a unified ISSU are designed to have a very short window of down time.

    11. After the unified ISSU reboot, the Packet Forwarding Engines restore the saved state information and connect back to the routing nodes. The chassis process on each routing node sends an ISSU_READY message to the chassis process on the global master Routing Engine. The CM_MSG_READY message from the chassis process on the routing nodes indicate that the unified ISSU is complete on the FRUs.
    12. The unified ISSU control moves back to the management process on the global master Routing Engine.
    13. The management process initiates Routing Engine switchover on the master Routing Engines.
    14. Routing Engine switchover occurs on the TX Matrix router and the T640 routers.
    15. After the switchover, the FRUs connect to the new master Routing Engines. Then the chassis manager and Packet Forwarding Engine manager on the T640 router FRUs connect to the new master Routing Engines on the T640 routers.
    16. The management process on the global master Routing Engine initiates the upgrade process on the old master Routing Engines on the T640 routers. (This step is skipped if you have specified the no-old-master-upgrade option in the request system software in-service-upgrade command.)
    17. After the Routing Engines that were previously the masters on the T640 routers are upgraded, the management process initiates the upgrade of the Routing Engine that was previously the global master on the TX Matrix router.
    18. After a successful unified ISSU, the TX Matrix router and the T640 routers are rebooted if you specified the reboot option in the request system software in-service-upgrade command.

    Modified: 2016-04-28