Nortel Networks 4050 manual One-armed and two-armed configurations

40Chapter 1 Overview

•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 “About the IP addresses” on page 51. For information about adding a node to a cluster, see “Adding a Nortel SNAS 4050 device to a cluster” on page 61.

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 “One-armed configuration” on page 41)

•two-armed configuration (see “Two-armed configuration” on page 41)

You specify whether the Nortel SNAS 4050 will function in a one-armed or two-armed configuration during initial setup (see “Initial setup” on page 49).

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