TCP/IP fundamentalsTCP/IP fundamentals

Unit objectivesDiscuss the evolution of TCP/IPDiscuss TCP/IP fundamentals

Topic ATopic ATopic A: Evolution of TCP/IPTopic B: TCP/IP fundamentals

EvolutionEvolution of TCP/IP of TCP/IPTCP/IP has moved from being a

specialty protocol used predominantly on UNIX-based minicomputers to the protocol of choice for many desktop computers

It is considered the universal default protocol to link dissimilar computer platforms such as UNIX, NetWare, OS/2, and Windows

A A brief historybrief historyThe three main protocols for the

Arpanet were◦NCP – (host-to-host communication)

◦FTP – (file transfer – same functions as today)

◦Telnet – (remote login)

One year later, NCP was replaced by a new layered protocol stack including TCP and IP.

TCP/IP became an immediate standard

Activity A-1 Activity A-1 page 9-3page 9-3

Discussing the history of TCP/IP

RFCsRFCsStands for Request for CommentsDefining document that sets the

standards for the Internet protocol suite◦RFCs are the mechanism for bringing many

new protocols and technologies to light. Someone writes a new protocol, publishes it as an RFC, gets comments and suggestions, uses it in a controlled environment and then gets more comments, and finally it is accepted or rejected as a new addition to the networking field. If accepted, it becomes a new “standard”.

RFCs are used for information and guidance.

Activity A-2 Activity A-2 page 9-5page 9-5

Discussing RFCs

The InternetThe InternetA collection of diverse networks,

each connecting a range of systems together for a distinct purpose

The common denominator between these networks is the use of TCP/IP

Activity A-3Activity A-3 page 9-7page 9-7

Discussing the Internet and supported systems

Topic BTopic B page 9-8 page 9-8

Topic A: Evolution of TCP/IPTopic B: TCP/IP fundamentals

TCP/IP fundamentalsTCP/IP fundamentalsTCP/IP◦The default protocol for UNIX and a

de facto standard for wide area networking◦Provides utilities to facilitate

communications and information sharing between dissimilar hardware platforms

Architectural modelArchitectural model of of TCP/IPTCP/IP

The OSI model has 7 layers while the TCP/IP model is normally seen as having 4. It may be more efficient to divide the lowest TCP/IP layer, “network interface” into 2 layers, but historically they comprise 1 layer, not 2.

The book, on page 9-10, asserts that “TCP/IP is based on a five-layer model….” It is not based on a 5-layer model. They distinguish the “TCP/IP” model, from the “4-layer DoD model”. But the TCP/IP model is the DoD model, and it is 4 layers, not 5. See, e.g., Lamlee, p.100 ff. See also, the next 3 slides:

Note, however, that a very small minority of sources do attribute a 5-layer model to DoD, but there seems to be not historical precedence for it.

Compare Models: OSI v. TCP/IPCompare Models: OSI v. TCP/IP

Compare Models: TCP/IP v. OSICompare Models: TCP/IP v. OSI

Compare Models: OSI v. TCP/IPCompare Models: OSI v. TCP/IP

But … this from a wireless articleBut … this from a wireless article There are a very few articles in

which the model in the book and to the right is used. It seems to want to separate the data-link and physical layer functions, as they are separated in the OSI model. This is not historically correct, however – the original version of the TCP/IP model had 4 layers. Nor does it match subsequent developments in the field. When the ISO decided that more layers were necessary to accurately reflect what is going on in networking technology, it went to a 7-layer model, not a 5-layer one.

Activity B-1 Activity B-1 page 9-11page 9-11

Discussing the architectural model of TCP/IP

[Note that the TCP/IP and the DoD models are described as 4-layer models – even in the book.]

TCP/IP suiteTCP/IP suiteCore protocols, utilities, and services

associated with the TCP/IP suite include:◦IP (Internet Protocol)◦TCP (Transmission Control Protocol)◦ICMP (Internet Control Message Protocol) ◦ARP/RARP ◦ (Address Resolution Protocol / Reverse Address

Resolution Protocol)

◦UDP (User Datagram Protocol)

continued

TCP/IP suite TCP/IP suite -- (see pages 9-12 to 9-14) (see pages 9-12 to 9-14)

◦Telnet◦HTTP (Hyper Text Transfer Protocol)◦FTP (File Transfer Protocol)◦SFTP (Secure File Transfer Protocol)◦TFTP (Trivial File Transfer Protocol)◦SMTP (Simple Mail Transfer Protocol - sends)◦POP3 (Post Office Protocol 3 – receives/holds)◦ IMAP (Internet Mail Access Protocol – store/organize)◦SNMP (Simple Network Management Protocol - agent)◦DNS (Domain Name System)

TCP/IP suiteTCP/IP suite

◦NFS (Network File Services - UNIX)◦NNTP (Network News Transport Protocol) ◦NTP (Network Time Protocol)◦SSH (Secure Shell or Secure Socket Shell - secure, remote

access)◦SCP (Secure Copy Protocol – (i.e., from 1 PC on a network to

another)

◦ LDAP (Lightweight Directory Access Protocol – (a protocol to allow simple access to directories)

◦ IGMP (Internet Group Multicast Protocol – allows network IP multicasts, - messages to multiple, but not all, nodes)

◦ LPD/LPR (Line Printer Daemon/Line Printer Remote)

Zero configuration IP networkingZero configuration IP networking

“zeroconf”Enables sharing of files and resources

in a TCP/IP network without manual (or dynamic) configuration

Is primarily used to create small home networks, or to create small networks on the fly ◦Lets you do some simple network tasks

without using some fairly complex utilities that would otherwise be required.

Activity B-2 Activity B-2 page 9-15page 9-15

Discussing the TCP/IP suite

A client/server environmentA client/server environment

Well-known portsWell-known portsWell-known ports are ports at which an

application listens for a request by default For example◦When a computer receives a packet destined for

port 21, that packet is given to the application running the FTP service because the FTP service listens on port 21 by default

The reason for this is that computers perform more than one task at a time. If two PCs are connected, they need a way to distinguish between the processes on each machine that need to communicate.

Unit summaryUnit summaryDiscussed the evolution of TCP/IPDiscussed TCP/IP fundamentals