Nortel Networks 4050 User Manual

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40 Chapter 1 Overview
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fault tolerance — If a Nortel SNAS 4050 device fails, the failure is detected 
by the other node in the cluster, which takes over the switch control and 
session handling functions of the failed device. As long as there is one 
running Nortel SNAS 4050, no sessions will be lost.
The devices in the cluster can be located anywhere in the network and do not have 
to be physically connected to each other. All the Nortel SNAS 4050 devices in the 
cluster must be in the same subnet. The cluster is created during initial setup of the 
second node, when you specify that the setup is a join operation and you associate 
the node with an existing Management IP address (MIP).
For more information about Nortel SNAS 4050 IP addresses, see 
. For information about adding a node to a cluster, see 
One-armed and two-armed configurations
The Nortel SNAS 4050 must interface to two kinds of traffic: client and 
management. The interface to the client side handles traffic between the 
TunnelGuard applet on the client and the portal. The interface to the management 
side handles Nortel SNAS 4050 management traffic (traffic connecting the Nortel 
SNAS 4050 to internal resources and configuring the Nortel SNAS 4050 from a 
management station). 
There are two ways to configure the Nortel SNAS 4050 interfaces: 
one-armed configuration (see 
two-armed configuration (see 
)
You specify whether the Nortel SNAS 4050 will function in a one-armed or 
two-armed configuration during initial setup (see