ISSU Limitations and Considerations

When using ISSU, consider the following capabilities and restrictions:
  • ISSU is supported on FastIron ICX 7150, ICX 7250, ICX 7450, ICX 7550, ICX 7650, and ICX 7850 stackable hardware.
  • ISSU is supported in a traditional ring stack topology.
  • ISSU works for stacks of two units to the maximum supported twelve units.
  • ISSU is supported for upgrades between minor releases only. For example, you can use ISSU to upgrade between FastIron 08.0.90 and FastIron 08.0.90a or between FastIron 08.0.90a and subsequent patch releases but not between FastIron 08.0.80 and FastIron 08.0.90.
  • For ISSU to occur with minimal disruption, the customer network connected to the stack must have redundant uplink and downlink configurations across multiple units.
  • If the secondary partition is upgraded, this partition is set as the default boot partition for the stack.
  • Most CLI commands, SNMP, and web operations are blocked while ISSU is in progress.
  • To make the upgrade seamless, the following administrative operations are blocked while ISSU is in progress:
    • Configuration
    • Image download to flash memory
    • Stack commands that may result in topology change or discovery
    • Initiation of another ISSU
Parent topic: In-Service Software Upgrade