In-Service Software Upgrade

In this section:

1. What Is an In-service Software Upgrade?
   An in-service software upgrade (ISSU) allows stack units or units in a Campus Fabric (SPX) system to be upgraded with minimal interruptions to multi-unit topologies.
2. ISSU Limitations and Considerations
   When using ISSU, consider the following capabilities and restrictions:
3. Recommended Stack Topology for ISSU
   ISSU provides an ability to upgrade traditional stacks without affecting the network.
4. How ISSU Works When Upgrading Stack Units
5. Upgrading a Stack with ISSU
6. Recommended Topology for Campus Fabric (SPX) ISSU
   ISSU provides the ability to upgrade Campus Fabric (SPX) systems with minimal traffic loss.
7. How ISSU Works When Upgrading a Campus Fabric (SPX) System
8. Upgrading a Campus Fabric (SPX) System with ISSU
9. ISSU Errors
   There are several sources of errors that may be encountered during an ISSU, and there are two means of error recovery.
10. Manual Error Recovery