Introduction To Issu; Issu Supported By The S9300 - Huawei Quidway S9300 Configuration Manual

Quidway S9300 Terabit Routing Switch
Configuration Guide - Device Management

10.1 Introduction to ISSU

In-Service Software Upgrade (ISSU) provides a mechanism to shorten service interruption
during upgrade and rollback of the software version. ISSU greatly reduces service interruption
time to the maximum extent during software upgrade, improving device reliability. ISSU also
minimizes the impact of upgrade failure on the system through rollback.
Requirements for the System
ISSU has the following requirements for the system:
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10.2 ISSU Supported by the S9300

The ISSU features include the ISSU modes, and the ISSU process.
ISSU Mode
S9300 supports two ISSU modes:
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The S9300 supports lossy ISSU. In lossy ISSU mode, the configurations of the original AMB
are synchronized to the new AMB. The dynamic data, however, is not synchronized.
ISSU Process
The ISSU process is as follows:
Issue 03 (2011-12-29)
The software running in the system supports ISSU.
Main control boards work in 1:1 backup mode. The interface board does not support 1:1
backup. During ISSU, the standby main board (SMB) is upgraded to the new version. Then
the SMB replaces the original active main board (AMB). Finally, the original AMB is
upgraded to the new version and ISSU of the whole device is complete.
The configuration data of different versions can be synchronized between the AMB and
SMB before the active/standby switchover. ISSU synchronizes the configuration data
between the AMB and the SMB by restoring configurations. That is, the AMB saves a
temporary configuration file, through which the SMB restores the configurations.
Lossless ISSU
In this mode, the configurations and data of the old AMB are synchronized with the new
AMB; the configurations and data of the old process on the interface board are synchronized
with the new process on the interface board. This upgrade mode requires a higher
performance of the system.
Lossy ISSU
In this mode, the configurations of the old AMB are synchronized with the new AMB; the
configurations of the old process on the interface board are synchronized with the new
process on the interface board; however, the dynamic data is not synchronized.
NOTE
In lossless or lossy ISSU, the interface board that does not support ISSU is commonly reset. In this way,
the interface board is commonly reset at the ISSU plane switch phase.
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