Cisco ASR1006 Configuration Guide - Page 87

Software Upgrade Process ISSU Upgrade for Redundant Platforms Cisco IOS XE release compatibility using the ISSU process utilizes the SSO functionality to preserve state while software versions on the router differ, as during an upgrade. Most SSO-capable features in each Cisco IOS XE release are ISSU capable. ISSU is only supported if SSO is enabled in the configuration and the system is in a steady state (SSO ready state has been achieved). ISSU compatibility depends on the set of specific feature clients that are in use and whether they support ISSU. All ISSU upgrades include at least one IOS switchover operation. It is important to understand which features are in use and whether these features are ISSU compatible. Cisco ASR1006 or ASR 1013 series routers are hardware-redundant chassis. The hardware-redundant chassis has two ESP linecards and two RPs which exchange state using hardware links. The Cisco ASR1002 and ASR1004 Series Routers are not hardware redundant, but are software-redundancy capable. The nonredundant chassis has a single RP and a single ESP, but allows the operation of up to two IOS processes on the single RP to exchange states locally. Restrictions for ISSU Restrictions for the ISSU procedures include: Note Cisco IOS XE software compatibility is between "like" images, for example, advipservicesk9 to advipservicesk9, adventerprisek9 to adventerprisek9, and so on. Cross-image-type upgrades or installations are not supported in the ISSU process. For example, you cannot upgrade ipbase to advipservicesk9 or advipservices to advipservicesk9. • Different image types must not be run simultaneously. • For ATM SPAs on the Cisco ASR1000 Series Routers, ISSU from releases prior to Cisco IOS XE Release 2.5.0 to Cisco IOS XE Release 2.5.0, or from Cisco IOS XE Release 2.5.0 to a release prior to Cisco IOS XE Release 2.5.0, is not supported. If you want to perform ISSU in this environment, you must first remove the configuration from the ATM SPAs on the router, and then shut down the SPAs using the shutdown command prior to running the ISSU process. • Cisco IOS XE releases not listed as compatible in the ISSU compatibility tables (documented in the Release Notes for Cisco ASR 1000 Series Aggregation Services Routers as stated in the "Prerequisites for Software Upgrade Process" section on page 2) must not be run simultaneously (in a Cisco ASR1006 series router or Cisco ASR 1013 series router) or co-installed on any of the Cisco ASR1000 Series Routers since unexpected failures of one or both RPs or state loss can be experienced. Cisco IOS XE releases listed as partially compatible may incur a loss of state. Cisco IOS XE releases listed as requiring an intermediate release are not directly compatible; however, a migration path is available to preserve some or all state by upgrading to a separate intermediate version, as shown in the tables. The tables do not cover nonredundant (software or hardware) environments as no incremental update is possible under those circumstances. • In Cisco IOS XE Release 3.1S, ISSU upgrade and subpackage software upgrade from Cisco IOS XE Release 2.x.x to Cisco IOS XE Release 3.x.xS, including release 3.1S, are not supported. The ISSU downgrade from Cisco IOS XE Release 3.x.xS, including release 3.1S to 2.x.x, is also not supported. ISSU upgrade and subpackage software upgrade is restarted from Cisco IOS XE Release 3.1S. Therefore, rebuilds and releases after Cisco IOS XE Release 3.1S will support ISSU and software upgrade and downgrade, based on the ISSU compatibility matrix tables. ISSU Upgrade Procedures This section contains the following topics: Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide 5