Management and Configuration Guide K/KA/KB.15.15

Transitioning from no redundancy to nonstop switching
While the switch is transitioning from no redundancy mode to Nonstop switching mode, no
configuration changes are allowed. The management modules are syncing information during the
transition period.
Setting the Rapid Switchover Stale Timer
Use the Rapid Switchover Stale Timer to set the amount of time that you want route and neighbor
table entries to be re-added to the Forwarding Information Base on the active management module
after a failover has occurred.
Layer 3 applications and protocols rely on existing routing information in the FIB. They restart and
operate as if the switch performed a quick reset.
When a failover occurs, the interface modules and the fabric modules continue forwarding Layer
3 traffic based on the information in the FIB. The transitioning standby management module marks
all routes in the FIB as “stale”. The routing protocols restart, reestablish their neighbors and
reconverge. As the routes are added in again, the route’s stale designation is removed. After the
Rapid Switchover Stale Timer expires, the remaining stale route entries are removed. Multicast
flows are also removed; the multicast application re-adds the flows after failover completes.
Syntax
redundancy rapid-switchover <0-2147483647>
Allows configuration of a timer (in seconds) for Layer 3 forwarding of packets when
Nonstop switching is configured for redundancy. After failover, the route and
neighbor entries in the Forwarding Information Base (FIB) on the active management
module are marked as stale. As new routes are added, the stale flag is reset. This
continues for the number of seconds indicated by the timer, after which all remaining
stale entries (entries not re-added) are removed.
A setting of zero indicates that no Layer 3 Nonstop switching behavior is wanted.
When the switch fails over, the FIB entries and corresponding hardware entries are
removed. Default: 90 seconds
To display information about stale FIB routes, enter the show tech route stale command. The VLAN
ID and IP route are shown, as well as other information used only for technical support.
Directing the standby module to become active
To make the standby management module become the active management module, use the
redundancy switchover command. The switch will switchover after all files have finished
synchronizing.
In Nonstop switching mode:
• The switchover occurs quickly and seamlessly. No reboot is needed.
• There is no interruption in switching operations.
In warm-standby mode:
• The switchover may take a couple of minutes if there have been recent configuration file
changes or if you have downloaded a new operating system.
• The standby module finishes booting and becomes the active module.
The formerly active module becomes the standby module if it passes selftest.
Syntax
redundancy switchover
Causes a switchover to the standby module.
For Nonstop switching, the warning displays:A nonstop switching failover
will occur; L2 operations will not be interrupted. This
466 Chassis Redundancy (8200zl Switches)