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5 - 34 WiNG 4.4 Switch System Reference Guide
5.4 Configuring Switch Redundancy & Clustering
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 provides centralized management from any single switch in the
network without restricting or dedicating 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, members discover and establish connections to other group members. 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 options. This 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 following example, there are four switches (WS1, WS2, WS3 and WS4) forming a redundancy group. Each switch
has established a TCP connection with the others 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
running on WS1, by duplicating the commands and sending them to the group over the virtual connection:
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