Motorola WS5100 manual Configuring Switch Redundancy, Root delay, Root Dispersion

Switch Services 5-25

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.

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