Availability Features
The OmniSwitch 8800
page 1-4
OmniSwitch 8800 Hardware Users Guide
December 2004
Smart Continuous Switching
In redundant CMM configurations, the switch provides support for NIs during failover. In other words, if
the primary CMM fails or goes offline for any reason, NI modules will continue data transmission and
routing functions during the secondary CMM’s takeover process. This Availability feature is referred to as
Smart Continuous Switching
.
Incoming Layer 2 packets will continue to be sent to the appropriate egress port during failover. Known
routes will also be supported. (Note, however, that the NI cannot learn new routes without CMM support.
Any new route information will be ignored.) Spanning Tree will continue handling BPDUs received on the
switch ports, as well as port link up and down states. The Spanning Tree topology will not be disrupted.
Note.
Smart Continuous Switching is designed to maintain data flow only during CMM failover and is
not
intended to support long-term data flow. If both the primary and secondary CMMs go offline or are
removed from the chassis, switch operations (including all NI support) will be disabled.
For more information on CMM redundancy and the failover process, refer to
Software Rollback
Software rollback (also referred to as
image rollback
) essentially allows the switch to return to a prior “last
known good” version of software in the event of a system software problem. The CMM controls software
rollback through its resilient directory structure design (i.e.,
/flash/working
and
/flash/certified
).
For detailed information on the software rollback feature, as well as the switch’s
/flash/working
and
/flash/certified
directories, refer to the “Managing CMM Directory Contents” chapter in the
OmniSwitch 7700/7800/8800 Switch Management Guide
.
