Internet technologies and their applications in BASs - Intelligent Buildings and Building Automation - page 97

OSI Reference Model Internet Protocol Suite

Application

Presentation

HTTP, FTP, Telnet, SMTP

Session

Transport TCP, UDP

Routing Protocols, IP

Network

ARP, RARP

Data Link

Not Specified

Physical

Figure 6.2 Internet protocols span the complete range of OSI model layers.

Control Protocol (TCP) and the Internet Protocol (IP). The Internet protocol
suite not only includes lower-layer protocols (such as TCP and IP), but it also
specifies common applications such as electronic mail, terminal emulation
and file transfer, etc.
Documentation of the Internet protocols (including new or revised pro-
tocols) and policies are specified in technical reports called 'Request for
Comments' (RFCs), which are published and then reviewed and analyzed
by the Internet community. Protocol refinements are published in the new
RFCs. To illustrate the scope of the Internet protocols, Figure 6.2 maps
typical protocols of the Internet protocol suite and their corresponding OSI
model layers. Internet protocols at Network Layer and Transport Layer are
discussed in more detail in this chapter.
Address Resolution Protocol (ARP) is a network protocol which maps a
Network Layer protocol address to a Data Link Layer hardware address.
For example, ARP is used to resolve an IP address to the corresponding
Ethernet address. ARP is extensively used by all the hosts in an Ethernet
network. Reverse Address Resolution Protocol (RARP) is a TCP/IP protocol
that permits a physical address, such as an Ethernet address, to be translated
into an IP address.

6.2.1 Internet Protocol (IP)

The Internet Protocol is a Network Layer protocol that contains addressing
information and some control information that enables packets to be routed.