Cisco ASR1002-5G-SEC/K9 Software Guide - Page 66

ISSU Upgrade for Redundant Platforms Chapter 4 Software Upgrade Process Software Upgrade with Dual IOS Processes on a Single RP Overview To complete a software upgrade of an individual subpackage using dual IOS processes on a single RP, SSO must first be enabled. Software upgrade with dual IOS processes is useful for upgrading the individual RP subpackages that can be upgraded without a router reload. See Table 4-1 for a list of these subpackages. Importantly, note that most subpackage upgrades in a single RP configuration require a hardware reload to complete (whether an RP reload for an RP subpackage, an ESP reload for the ESPBase subpackage, a SIP reload for a SIPBase subpackage, or a SPA reload for the SIPSPA subpackage), so limited interruption upgrades for single RP configurations are not available in most upgrade scenarios. For information on configuring a second IOS process on a single RP, see the "Using SubPackages for Software Upgrade on a Cisco ASR 1002 or Cisco ASR 1004 Router (software upgrade Command Set)" section on page 4-94. Cisco IOS XE Software Package Compatibility for ISSU When upgrading the Cisco IOS XE operating system software using the ISSU process, it is important to determine the compatibility of the upgraded software to your current software and hardware. The ISSU process allows software to be updated or otherwise modified while packet forwarding continues with minimal interruption. 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. Prerequisites for ISSU Be sure to complete the following prerequisites for running the ISSU process based on your chassis model: • Refer to the ISSU compatibility tables in the Release Notes for Cisco ASR 1000 Series Aggregation Services Routers. • 4 GB of DRAM memory is required for installing software upgrade on a system with RP1 route processor. • ISSU is supported when the router is running in subpackage mode or in consolidated package mode. Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide 4-4 OL-16506-10