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1. The standby management module resets and reloads with the new software image in its flash
memory.
2. The Ethernet interfaces (if present) on the standby module become operational and start carrying
data traffic.
3. The active management module synchronizes the standby management module with all the
information required to take over the active role.
4. The Layer 2 and Layer 3 control protocols on the standby management module converge. This
process takes approximately 70 seconds.
5. The standby management module takes over the active role.
6. The old active management module resets and reloads with the same software image running on
the newly active management module.
7. The FastIron switch is now operating with the new software image. The management module that
was initially configured as the standby management module is now the active management module
and the management module that was initially configured as the active management module is now
the standby.
NOTE
The events described above occur internally and do not create or affect the external network
topology.
Hitless OS upgrade considerations
Consider the following when using the hitless OS upgrade feature:
• Hitless OS upgrade allows for upgrading the software in a system between two releases of the OS
that support this functionality and have compatible data structures. A hitless O/S downgrade may
also be supported if the current and target code releases have compatible data structures. From
time to time it may be necessary, when enhancing the software or adding new features, to change
or add data structures that may cause some releases to be incompatible. In such cases, an
upgrade or downgrade will not be hitless, and the software will use the regular Brocade upgrade
process - relying on fast reboot.
• For a description of how this feature impacts major system functions, refer to Supported protocols
and services for hitless management events on page 123.
• You must have both active and standby management modules installed to use this feature.
• Hitless OS upgrade is supported in software release FSX 05.0.00 or higher, with boot image FSX
05.0.00 or higher. In general, it is supported with patch upgrades, for example, when upgrading
from release 07.0.01a to 07.0.01b. It is not supported during major release upgrades, for example
when upgrading from release 07.0.00 to 07.1.00.
• This feature can be used to upgrade an image to a higher or lower compatible version of the
software. However, if hitless upgrade to a particular software version is not supported, the software
upgrade must be performed through a fast reload of the system.
• Hitless OS upgrade between different types of software images is not supported. For example,
hitless OS upgrade is supported when upgrading the Layer 2 image to another Layer 2 image. It is
not supported when upgrading the Layer 2 image to Layer 3 image, and so on.
• Hitless OS upgrade should be performed locally, since remote connectivity will be lost during the
upgrade. During a reload, HTTP, SSH, Telnet, SNMP, and ping sessions will be dropped.
• The active management module switches from the initial active management module to the standby
management module during the hitless upgrade process. Therefore, a connection to the console
interface on both management modules is required.
• Upon being reset, any traffic going through the ports on the management module will be interrupted.
Once the management module is up and running, it will be able to send and receive packets, even
before the hitless upgrade process is complete.
• The running configuration is not allowed to be changed any time during the hitless upgrade process.
Hitless OS upgrade considerations
130 FastIron Ethernet Switch Administration Guide
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