Motorola Series Switch WS5100 - Manual (Page 195)

Switch Services 5-25
5.4 Configuring Switch Redundancy
Configuration and network monitoring are two tasks a network administrator faces as a network grows in
terms of the number of managed nodes (switches, routers, wireless devices etc.). Such scalability
requirements lead network administrators to look for managing and monitoring each node from a single
centralized management entity. The switch not only provides a centralized management solution, it goes one
step further to provide centralized management from any single switch in the network without restricting or
dedicating a one switch as a centralized management node. This eliminates dedicating a management entity
to manage all redundancy members and eliminates the possibility of a single point of failure.
A redundancy group (cluster) is a set of switches (nodes) uniquely identified by group/cluster ID. Within the
redundancy group, member switches discover and establish connections to other members of the group. The
redundancy group has full mesh connectivity using TCP as the transport layer connection.
Up to 12 switches can be configured as members of a redundancy group to significantly reduce the chance
of a disruption in service to WLANs and associated MUs in the event of failure of a switch or intermediate
network failure. All members can be configured using a common file (cluster-config) using DHCP based
options. This new functionality provides an alternative method for configuring members collectively from a
centralized location, instead of configuring specific redundancy parameters on individual switches.
Configure each switch in the cluster by logging in to one participating switch. The administrator does not
need to login to each redundancy group member, as one predicating switch can configure each member in
real-time without “pushing” configurations between switches. A new CLI context called "cluster-cli" is
available to set the configuration for all members of the cluster. All switch CLI commands are considered
cluster configurable.
In the example below, there are four wireless switches (WS1, WS2, WS3 and WS4) forming a redundancy
group. Each switch has established a TCP connection with the other switches in the group. There is an
additional CLI context called cluster-context. A user/administrator can get into this context by executing a
"cluster-cli enable" under the CLI interface (future releases will have this support in the Web UI and SNMP
interfaces). When the user executes this command on WS1, WS1 creates a virtual session with the other
switches in the redundancy group (WS2, WS3 and WS4). Once the virtual session is created, any command
executed on WS1 is executed on the other switches at the same time. This is done by the cluster-protocol
Root delay The total round-trip delay in seconds.This variable can take on both positive and negative
values, depending on the relative time and frequency offsets. The values that normally
appear in this field range from negative values of a few milliseconds to positive values of
several hundred milliseconds.
Root Dispersion Displays the nominal error relative to the primary time source in seconds. The values that
normally appear in this field range from 0 to several hundred milliseconds.