H3C Technologies H3C S12500 Series Switches - Manual (Page 142)

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This method does not require upgrade hotfixes in the system software image. It upgrades each member
switch through switch reboot, thus causing a brief interruption to the traffic passing through the member
switches. H3C recommends that you aggregate links on different interface cards or even different
switches to avoid traffic interruption during the upgrade process.
This method is not applicable when the version compatibility check result is incompatible.
Member switch-based ISSU upgrade for incompatible versions
With this method, each member switch is considered as a separate switch.
To perform a member switch-based ISSU upgrade for an incompatible version:
1. Upgrade a subordinate switch when the master is operating correctly.
2. Perform a master/subordinate switchover, so that the subordinate switch becomes the new master
and the former master and the other switches get upgraded.
This method does not require upgrade hotfixes in the system software image. It upgrades each member
switch through switch reboot, thus causing a brief interruption to the traffic passing through the member
switches. H3C recommends that you aggregate links on different interface cards or even different
switches to avoid traffic interruption during the upgrade process.
This method requires that the IRF connection is a ring connection if there are more than two members. If
you do not follow this guideline, the IRF fabric will be partitioned during upgrade and the upgrade
process will be out of control.
This method is not applicable when the version compatibility check result is compatible or partially
compatible.
Member switches-based ISSU upgrade (for incompatible versions only)
With this method, multiple member switches are considered as a whole.
To perform a member switches-based ISSU upgrade:
1. When the master is operating correctly, upgrade two or more subordinate switches.
2. Perform a master/subordinate switchover so that an upgraded subordinate switch (the one with
the highest priority) becomes the new master and the former master and the other switches get
upgraded.
This method does not require upgrade hotfixes in the system software image. It upgrades each member
switch through switch reboot, thus causing a brief interruption to the traffic passing through the member
switches. H3C recommends that you aggregate links on different interface cards or even different
switches to avoid traffic interruption during the upgrade process.
This method requires that the IRF connection is a ring connection if there are more than two members. If
you do not follow this guideline, the IRF will be partitioned during upgrade and the upgrade process will
be out of control.
The subordinate switches to be upgraded first must be physically connected.
This method is not applicable when the version compatibility check result is compatible or partially
compatible.
This method is a good choice for upgrading a four-member IRF fabric. By upgrading more than one
member first, this method helps improve the reliability of the ISSU upgrade and the service continuity
during the upgrade.