Cisco Catalyst 4500 Series Configuration Guide

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Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
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Chapter 6 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 6-8 on page 6-11.
This section includes the following topics:
• Verifying the ISSU Software Installation, page 6-15
• Loading New Cisco IOS XE Software on the Standby Supervisor Engine, page 6-18 (required)
• Switching to the Standby Supervisor Engine, page 6-21 (required)
• Stopping the ISSU Rollback Timer (Optional), page 6-23 (optional)
• Loading New Cisco IOS XE Software on the New Standby Supervisor Engine, page 6-24 (required)
• Using changeversion to Automate an ISSU Upgrade, page 6-25
• Aborting a Software Upgrade During ISSU, page 6-31
• Configuring the Rollback Timer to Safeguard Against Upgrade Issues, page 6-32
• Displaying ISSU Compatibility Matrix Information, page 6-34
Verifying the ISSU Software Installation
During the ISSU process, there are five valid states: disabled, init, load version, run version, and system
reset. Use the show issu state command to obtain the current ISSU state:
• Disabled state—The state for the standby supervisor engine while this engine is resetting.
• Init state—The initial state for two supervisor engines, one active and one standby, before the ISSU
process is started. It is also the final state after the ISSU process completes.
• Load version (LV) state—The standby supervisor engine is loaded with the new version of Cisco
IOS XE software.
• Run version (RV) state—The issu runversion command forces the switchover of the supervisor
engines. The newly active supervisor engine runs the new Cisco IOS XE software image.
• While running ISSU, if both supervisor engines are reset due to power outage, for example, the ISSU
context is lost and returns to the init state. Both supervisor engines return to the old software.

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E