User guide

September 2009
OmniSwitch 6400/6850/6855/9000/9000E------ Release 6.4.2.R01 Page 49 of 79
MAC Address Mode
There are two source learning modes available for the OmniSwitch chassis-based systems: synchro-
nized and distributed. By default the switch runs in the synchronized mode, which allows a total MAC
address tables size of 16K per chassis. Enabling the distributed mode for the switch chassis increases
the table size to 16K per module and up to 64K per system..
Note: The distributed MAC address mode is only supported chassis-based systems.
Software Rollback
The directory structure inherent in an OmniSwitch switch allows for a switch to return to a previous,
more reliable version of image or configuration files.
Changes made to the configuration file may alter switch functionality. These changes are not saved
unless explicitly done so by the user. If the switch reboots before the configuration file is saved,
changes made to the configuration file prior to the reboot are lost.
Likewise, new image files should be placed in the working (non-certified) directory first. New image
or configuration files can be tested to decide whether they are reliable. Should the configuration or
image files prove to be less reliable than their older counterparts in the certified directory, then the
switch can be rebooted from the certified directory, and “rolled back” to an earlier version.
Once the contents of the working directory are established as good files, then these files can be saved
to the certified directory and used as the most reliable software to which the switch can be rolled back
to in an emergency situation.
Spanning Tree
In addition to the Q2005 version of MSTP, the Alcatel-Lucent Spanning Tree implementation also
provides support for the 802.1w Rapid Spanning Tree Algorithm and Protocol (RSTP) and the 802.1D
Spanning Tree Algorithm and Protocol (STP). All three supported protocols ensure that there is always
only one data path between any two switches for a given Spanning Tree instance to prevent network
loops.
Q2005 (MSTP) is only available when the flat mode is active for the switch. The flat mode applies a
single spanning tree instance across all VLAN port connections on a switch. MSTP allows the
configuration of Multiple Spanning Tree Instances (MSTIs) in addition to the CST instance. Each
MSTI is mapped to a set of VLANs. As a result, flat mode can now support the forwarding of VLAN
traffic over separate data paths.
802.1D STP and 802.1w RSTP are available in both the flat and 1x1 mode. However, when using
802.1D or 802.1w in the flat mode, the single spanning tree instance per switch algorithm applies. Note
that 802.1w is now the default Spanning Tree protocol for the switch regardless of which mode is
active. This default value will apply to future releases as well.
Syslog to Multiple Hosts
Sending syslog files to multiple hosts is allowed. It is possible to specify up to a maximum of four
servers.
Switch Logging
The Switch Logging feature is designed to provide a high-level event logging mechanism that can be
useful in maintaining and servicing the switch. Switch Logging uses a formatted string mechanism to
process log requests from applications. When a log request is received, Switch Logging verifies
whether the Severity Level included with the request is less than or equal to the Severity Level stored
for the appropriate Application ID. If it is, a log message is generated using the formatting specified by
the log request and placed on the Switch Log Queue, and Switch Logging returns control back to the
calling application. Otherwise, the request is discarded. The default output device is the log file located