Nortel Networks NN46120-104 User Manual

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VIP (Virtual Server IP) Address

An IP address that the switch owns and uses to load balance
particular service requests (like HTTP) to other servers.

Virtual Router

A shared address between two devices utilizing VRRP, as defined
in RFC 2338. One virtual router is associated with an IP interface
defined on the Nortel Application Switch. All IP interfaces on a
Nortel Application Switch must be in a VLAN. If there is more
than one VLAN defined on the Application Switch, then the
VRRP broadcast will only be sent out on the VLAN to which the
associated IP interface has been added.

Virtual SSL Server

A virtual SSL server handles a specific service on the VPN
Gateway, such as HTTPS, SMTPS, IMAPS, or POP3S. You
can create an unlimited number of virtual SSL servers per NVG
cluster, and each virtual SSL server is mapped to a virtual server
on the Nortel Application Switch. To authenticate itself towards
clients making requests for the specified service, the virtual SSL
server is configured to use a digital certificate.

VLAN (Virtual Local Area Network)

VLANs are commonly used to split up groups of network
users into manageable broadcast domains, to create logical
segmentation of workgroups, and to enforce security policies
among logical segments. Up to 246 VLANs are supported on a
Nortel Application Switch running Web OS.

VRRP (Virtual Router Redundancy Protocol)

A protocol similar to Cisco’s proprietary HSRP address-sharing
protocol. The reason for both of these protocols is to ensure
devices have a next hop or default gateway that is always
available. For example, two or more devices sharing an IP
interface are either advertising or listening for advertisements.
These advertisements are sent through a broadcast message to
address 224.0.0.18.

With VRRP, one switch is considered the master and the
other is the backup. The master is always advertising through
the broadcasts. The backup switch is always listening for the
broadcasts. Should the master stop advertising, the backup will
take over ownership of the VRRP IP and MAC addresses as
defined by the specification. The switch announces this change
in ownership to the devices around it by way of a gratuitous ARP
and advertisements. If the backup switch didn’t do the gratuitous

Nortel VPN Gateway

User Guide

NN46120-104

02.01

Standard

14 April 2008