This is my Experience of Upgrading Nexus 7000 series switches without disturbing the existing traffic.
ISSU Introduction
In a Nexus 7000 series chassis with dual supervisors, you can use the in-service software upgrade (ISSU) feature to upgrade the system software while the system continues to forward traffic. An ISSU uses the existing features of nonstop forwarding (NSF) with stateful switchover (SSO) to perform the software upgrade with no system downtime.
An ISSU is initiated through the command-line interface (CLI) by an administrator. When initiated, an ISSU updates (as needed) the following components on the system:
•Supervisor BIOS, kickstart image, and system image
•Module BIOS and image
•Connectivity Management Processor (CMP) BIOS and image
In a redundant system with two supervisors, one of the supervisors is active while the other operates in the standby mode. During an ISSU, the new software is loaded onto the standby supervisor while the active supervisor continues to operate using the old software. As part of the upgrade, a switchover occurs between the active and standby supervisors, and the standby supervisor becomes active and begins running the new software. After the switchover, the new software is loaded onto the (formerly active) standby supervisor.
An ISSU-based upgrade is a system-wide upgrade that applies the same image and versions across the entire system, including all configured virtual device contexts (VDCs). VDCs are primarily a control-plane and user-interface virtualization and cannot run independent image versions per virtualized resource.
Guidelines and Limitations
An ISSU has the following limitations and restrictions:
•Do not change any configuration settings or network connections during the upgrade. Any changes in the network settings may cause a disruptive upgrade.
•In some cases, the software upgrades may be disruptive. These exception scenarios can occur under the following conditions:
–A single supervisor system with kickstart or system image changes.
–A dual-supervisor system with incompatible system software images.
•Configuration mode is blocked during the ISSU to prevent any changes
How an ISSU Works
On a Nexus 7000 series with two supervisors, the ISSU process follows these steps:
1. Begins when the administrator uses the install all command
2. Verifies the location and integrity of the new software image files
3. Verifies the operational status and the current software versions of both supervisors and all switching modules to ensure that the system is capable of an ISSU
4. Loads the new software image to the standby supervisor and brings it up to the HA ready state
5. Forces a supervisor switchover
6. Loads the new software image to the (formerly active) standby supervisor and brings it up to the HA ready state
7. Performs a nondisruptive upgrade of each switching module, one at a time
8. Upgrades the Connectivity Management Processor (CMP)
During the upgrade process, the system presents detailed status information on the console, requesting administrator confirmation at key steps.
Determining ISSU Compatibility
An ISSU may be disruptive if you have configured features that are not supported on the new software image. To determine ISSU compatibility, use the show incompatibility system command.
You can check this documentation for more details.
We will continue with Part 2 for the more installation and compatibility checks.