User Guide

Chapter 1 Overview 39
Nortel Secure Network Access Switch 4050 User Guide
The Nortel SNAS 4050 supports the use of three different SSH host key types:
•RSA1
•RSA
•DSA
SSH protocol version 1 always uses RSA1 keys. SSH protocol version 2 uses
either RSA or DSA keys.
For management communications in the Nortel SNA solution, the Nortel
SNAS 4050 can act both as SSH server (when a user connects to the CLI using an
SSH client) and as SSH client (when the Nortel SNAS 4050 initiates file or data
transfers using the SCP or SFTP protocols).
For information about managing SSH keys for communication between the Nortel
SNAS 4050 and the network access devices, see “Managing SSH keys using the
CLI” on page 84 or “Managing SSH keys using the SREM” on page 102.
For information about managing SSH keys for Nortel SNAS 4050 management
communications, see “Configuring Nortel SNAS 4050 host SSH keys using the
CLI” on page 485 or “Configuring Nortel SNAS 4050 host SSH keys using the
SREM” on page 548.
Nortel SNAS 4050 clusters
A cluster is a group of Nortel SNAS 4050 devices that share the same
configuration parameters. Nortel Secure Network Access Switch
Software Release 1.0 supports two Nortel SNAS 4050 devices, or nodes, in a
cluster. A Nortel SNA network can contain multiple clusters.
Clustering offers the following benefits:
• manageability — The cluster is a single, seamless unit that automatically
pushes configuration changes to its members.
• scalability — The Nortel SNAS 4050 nodes in a cluster share the burden of
resource-intensive operations. The cluster distributes control of the network
access devices between the Nortel SNAS 4050 nodes and distributes handling
of session logon. As a result, Nortel SNAS 4050 devices in a cluster can
control more switches and handle more user sessions.