Network Interface (NI) Modules
Hot Swapping NI Modules
OmniSwitch 7700/7800 Hardware Users Guide
April 2005
page 5-23
Hot Swapping NI Modules
You are not required to enter a CLI command in order to hot swap NI modules. The hot swap function can
be performed on the fly by simply removing the module from the switch chassis. For information on prop-
erly removing modules, refer to
“Removing a Module” on page 5-25
Module Presence Signalling
On-the-fly module removal is provided through the presence signalling function. All modules in the
switch send out “presence signals.” When a module sends out this signal, it is essentially advertising to all
other modules in the switch that it is present in the chassis. When a module is present, information such as
its module type (primary CMM, secondary CMM, ENI, or GNI) becomes available for monitoring func-
tions.
The presence signal is controlled through a shortened connector pin that interfaces with the switch’s back-
plane. Because this connector pin is shorter than the module’s other backplane connectors, the presence
signal connection is the first to become interrupted when a board is removed from the chassis. This allows
the switch additional time (approximately 5 ms) to complete the current transfer of data before the module
is completely disconnected. (In order to avoid data loss, the switch immediately stops incoming traffic and
flushes outgoing traffic on the module being removed.)
Note.
Although presence signalling is designed to maintain data flow on the switch during the hot swap
procedure, uninterrupted data flow cannot be guaranteed. As a result, you should not hot swap NI or CMM
modules during critical network activity.
