Cisco Catalyst 4500 Series - How to Perform the ISSU Process

8-16
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 8 Configuring the Cisco IOS XE In Service Software Upgrade Process
How to Perform the ISSU Process
• Compare two IOS XE software images and understand the compatibility level of the software
images (that is, compatible, base-level compatible, and incompatible), or dynamically determined.
• Compare two software images and see the client compatibility for each ISSU client.
• Provide links to release notes for the software image.
How to Perform the ISSU Process
Unlike SSO, which is a mode of operation for the device and a prerequisite for performing ISSU, the
ISSU process is a series of steps performed while the switch is in operation. The steps result in an
upgrade to new or modified Cisco IOS XE software, and have a minimal impact to traffic.
Note For an illustration of the process flow for ISSU, refer to Figure 8-8 on page 8-12.
This section includes the following topics:
• Upgrading ISSU to Cisco IOS XE 3.4.0SG/15.1(2)SG from a Prior Release, page 8-16
• Downgrading ISSU from Cisco IOS XE 3.4.0SG/15.1(2)SG to a Prior Release, page 8-18
• Verifying the ISSU Software Installation, page 8-19
• Loading New Cisco IOS XE Software on the Standby Supervisor Engine, page 8-21 (required)
• Switching to the Standby Supervisor Engine, page 8-25 (required)
• Stopping the ISSU Rollback Timer (Optional), page 8-27 (optional)
• Loading New Cisco IOS XE Software on the New Standby Supervisor Engine, page 8-28 (required)
• Using changeversion to Automate an ISSU Upgrade, page 8-30
• Aborting a Software Upgrade During ISSU, page 8-36
• Configuring the Rollback Timer to Safeguard Against Upgrade Issues, page 8-37
• Displaying ISSU Compatibility Matrix Information, page 8-39
Upgrading ISSU to Cisco IOS XE 3.4.0SG/15.1(2)SG from a Prior Release
Because images prior to Cisco IOS XE 3.4.0SG/15.1(2)SG use the earlier CLI format and Cisco IOS XE
3.4.0SG and 15.1(2)SG images use a newer CLI format, your upgrade consists of the following:
• Upgrading the image on your switch to Cisco IOS XE 3.4.0SG/15.1(2)SG.
• Upgrading mgmtVrf from the earlier CLI format to the later format, removing any IPv6 addresses
on the interface.
• Enabling IPv6 address family under mgmtVrf, and reconfigure IPv6 addresses on fa1.
A configuration like the following should exist on pre-Cisco IOS XE 3.4.0SG/15.1(2)SG image:
ip vrf mgmtVrf
!
interface FastEthernet1
ip vrf forwarding mgmtVrf
ip address 10.1.1.1 255.255.255.0
speed auto
duplex auto
ipv6 address 2000::1/64