TCP/IP Configuration and Management Manual

NonStop TCP/IP Processes and Protocols
TCP/IP Configuration and Management Manual—427132-004
B-8
The Problem of Resolving Addresses
Example: Configuring an Intranet Using Subnetting
Your company is headquartered in Omaha and has branch offices in Atlanta, Los
Angeles, Seattle, and New York. The headquarters has 100 hosts, Atlanta has 17, Los
Angeles has 30 hosts, Seattle has 12 hosts and New York has 65 hosts. The objective
is to design the subnet masking scheme to accommodate all the offices and to allow
for growth. Figure B-4 shows the Intranet described in this example.
Task 1: Apply for a Class B Internet Network Address
Their address is:
DDN Network Information Center
SRI International, EJ291
333 Ravenswood Avenue
Menlo Park, CA 94025
In this example, assume that the class B Internet address assigned to Omaha is
130.10.128.3
Task 2: Create Subnets for Each Office Network
1. In this case you have more hosts than physical networks; divide the two octets of
the local address such that more bits are available for hosts. Table B-1 shows that
the maximum bits you need for hosts is 10; therefore, you need 10 bits to represent
hosts. This leaves the remaining six bits in the local address portion (as shown in
Figure B-5) to indicate a subnet. Six bits allows for up to 64 subnets, each with a
maximum of 1,024 hosts.
Figure B-4. Example of a Corporate Intranet
023VST .VSD
To Internet
Corporate Backbone