User Guide

12 NetWare TCP/IP Administration Guide
NetWare TCP/IP Administration Guide
103-000151-001
August 30, 2001
Novell Confidential
Manual 99a38 July 17, 2001
illustrates the seven layers of the OSI reference model, as defined by ISO, and
the roughly corresponding layers of the TCP/IP protocol suite.
Figure 1 OSI Reference Model
The layering system allows the developers to concentrate their efforts on the
functions in a given layer. It is not necessary for designers to create all the
mechanisms to send information across the network. They have to know only
what services the software needs to provide to the layer above it, what services
the layers below it can provide to the software, and which protocols in the
suite provide those services.
Table 1 lists some of the more common protocols in the TCP/IP suite and the
services they provide.
Table 1 TCP/IP Protocols
Protocol Service
Internet Protocol (IP) Provides packet delivery services (routing)
between nodes.
Internet Control Message
Protocol (ICMP)
Provides transmission of error and control
messages between hosts and routers.
OSI Reference Model
TCP/IP Protocol Suite
Protocol
Function
Layer
TELNET
FTP SMTP
DNS
SNMP
Ethernet
Token
Ring
Other
Media
Presentation
2
Application
1
Session
3
Transport
4
Network
5
Data Link
6
Physical
7
ICMP
TCP
UDP
IP
ARP
RARP
EGP
OSPFRIP