User`s guide

5-20
Filters
• Using a firewall filter to prevent problems and enhance
performance.
For each application example, the situation is described first, and
the objective to be accomplished is explained. Then, how the
objective would be accomplished using the ATX is explained in
general terms. In these examples, single letters are used to
represent MAC-layer addresses. Real MAC addresses consist of a
string of numbers, (22:14:15:4:5:6).
Note: The way that you configure filters will depend on the NMS you use.
Instructions for using LCM to set up your filters are described in
this chapter; refer to your NMS documentation if that is the tool
you are using to set up your filter.
5.10.1 Filtering for Security Purposes
Example 1 — Blocking access to a network segment
The objective in this example is to restrict access for security
reasons. Workstations on one network segment (subnet) are to be
restricted entirely from access to devices on an adjoining subnet.
In this example there are three subnets connected by a centrally
located ATX (Figure 5-1). The subnets are referred to as the
Engineering, Accounting and FDDI backbones.