Specifications

Niagara Release 2.3
Revised: May 22, 2002 Niagara Networking & Connectivity Guide
Chapter 1 Understanding Networking and IP Addressing
Introduction to Networking
1–10
station, handed down to the lower layers in the stack for actual transport processing,
over the channel to the next station, then handed up the stack to the appropriate
application in the receiving station.
The IEEE 802
Standards
The IEEE 802 standards, or Project 802, is a set of network standards developed by
the IEEE that define network standards for the physical components of a network.
These standards have several areas of responsibility including:
• Network interface cards
• Wide area network components
• Components used to create twisted pair and coaxial cable networks
The 802 specification defines the way network interface cards access and transfer
data over physical media including connecting, maintaining, and disconnecting
network devices. IEEE 802 categories are listed in Table 1-4.
Table 1-3 OSI layers.
Layer Name Basic Function
7 Application Defines the language and syntax that programs use to
communicate with each other. Common functions at this layer
include file open, file close, read and write, and file transfer.
6 Presentation Translates data into a format that is understood by the receiving
computer. For example, this layer might convert BCD to binary. This
layer is also used for encryption and decryption.
5 Session Establishes and manages transmissions between stations,
synchronizes transmissions, and handles errors from higher levels.
It is the session layer that makes sure the previous request has
been fulfilled before the next one is sent.
4 Transport This layer is responsible for overall end to end validity and integrity
of the transmission. It ensures that if a 12MB file is sent, the full
12MB file is received.
3 Network Determines the best path to specific network destinations and
routes data along that path.
2 Data Link Is responsible for delivering data packets from one node to another
- ensuring that the bits that are received are the same bits that were
sent.Due to the significant level of detail needed to define
node-to-node communications, the IEEE 802 standards committee
recently divided the data link layer into two sub-layers: the logical
link layer (LLC) and the media access layer (MAC). The logical link
layer supports flow control and the MAC layer provides access and
error control.
1 Physical Passes bits onto and receives them from the physical connecting
medium. This layer has no understanding of the meaning of the bits,
it simply deals with the electrical and mechanical characteristics of
the signals and signaling methods.
Table 1-4 IEEE 802 categories.
Number Description
802.1 Covers network management and internetworking.
802.2 Logical Link Control (LLC). Specifies the data link
layer for the media access control (MAC) layers
defined in 802.3 to 802.5.