Specifications

Chapter 1 Understanding Networking and IP Addressing
Networking using IP
Niagara Release 2.3
Niagara Networking & Connectivity Guide Revised: May 22, 2002
1–17
• IP Address Allocation—discusses how addresses are allocated, and
technologies such as private addressing and network address translation.
• Associating IP Addresses with Host Names—discusses name resolution
techniques including HOSTS files, DNS, DDNS, and WINS.
• Proxy Servers and Firewalls—talks about these special devices on an IP
network. Also included is a review of TCP/IP ports.
What is IP?
The Internet originated as a means of interconnecting computers between
universities that were doing research for the Department of Defense. It has a number
of communication standards that include:
• Internet Protocol (IP)
• Transmission Control Protocol (TCP)
• Hypertext Transfer Protocol (HTTP)
• Hypertext Markup Language (HTML)
IP is one of the standard protocols for sending data on the Internet. It is responsible
for addressing and routing of packets between the source and destination computers
(called hosts). Additionally, IP determines if the data is destined for a local or a
remote network and then routes the data appropriately.
IP is sometimes referred to as a connectionless protocol because it has no concept of
a sequence. Each bit of data is contained in a packet which has no knowledge of other
packets. Therefore, it is an unreliable protocol and must be teamed with another
protocol (such as TCP) to increase reliability. TCP preserves the sequence of
messages sent on the same connection to ensure reconstruction of the message.
IP has gone through several versions since it was originally developed. The current
standard is version 4 (written as IPv4), though IPv6 has been ratified and will
gradually replace IPv4. This document focuses on IPv4 since that is the current
standard.
The OSI Model
and TCP/IP
The following discussion uses the OSI model (see “The OSI Model and the IEEE 802
Standards”) as it relates to native TCP/IP protocol.
Application Layer
This is the top layer of the protocol stack. It includes network software that directly
serves the user, providing such things as user interface and application features. The
application layer is usually made public through Application Programming
Interfaces (API) provided by the vendor. This layer does not actually include
application software, but it does enable commercial software to use network services.
TCP/IP includes several application layer protocols for mail, file transfer, remote
access, authentication, and name resolution. FTP (File Transfer Protocol) programs
are widely used to copy files across a network. All TCP/IP based mail programs use
SMTP (Simple Mail Transfer Protocol) to send e-mail. Telnet is a terminal emulator