Brocade FastIron Ethernet Switch Administration Guide - Manual (Page 117)

Hitless reload or switchover requirements and limitations
The section describes the design limitation on devices with the following configuration:
• 0-port management modules
• One or more third generation line cards
For hitless reload or switch-over-active-role to succeed, the following requirements and limitations must
be met:
• Hitless reload is not allowed from Switch code when the primary image is in Router code and boot
primary is a part of the configuration.
• The standby management module must be up and in an "OK {Enabled}" state.
• A configuration requiring a reload must not be pending.
• A hitless-reload must not have already been issued on the previous active management module.
• POE firmware must not be in progress.
• The SXR running configuration must not be classified as too large (greater than 512KB).
• A TFTP session must not be in progress.
• An image sync session must not be in progress.
• The current active management card cannot have a memory utilization of greater than 90% of
available memory.
• A line card hotswap must not be in progress.
If any of these conditions are not met, an appropriate error message is printed to the console and
hitless-reload or switch-over will not succeed.
With following steps, after switchover, the new standby goes into continuous reload state:
1. SXL box is running with build "x"
2. Perform copy tftp of build "x+1" and wait for both active and standby to sync.
3. Execute switch-over-active-role.
With above step, the new active comes up but the new standby tries to load the primary image "x+1"
and due to this there is image sync issue and new standby goes to continuous reload state without
recovery. Hence, it is a limitation that after copy tftp operation to primary, switch-over-active-role
operation should be avoided.
What happens during a Hitless switchover or failover
This section describes the internal events that enable a controlled or forced switchover (failover) to take
place in a hitless manner, as well as the events that occur during the switchover.
Separate data and control planes
The FSX 800 and FSX 1600 management modules have separate data and control planes. The data
plane forwards traffic between the switch fabric modules and all of the Interface modules in the chassis.
The control plane carries traffic that is destined for the CPU of the active management module. Control
plane traffic includes the following:
• Management traffic
• Control protocol traffic
• In some cases, the first packet of a data flow
During a controlled or forced switchover, the data plane is not affected. Traffic in the forwarding plane
will continue to run without interruption while the standby management module takes over operation of
the system. However, traffic in the control plane will be minimally impacted.
Hitless reload or switchover requirements and limitations
FastIron Ethernet Switch Administration Guide 117
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