IACT303 – INTI 2005 IACT303 – INTI 2005 World Wide NetworkingWorld Wide NetworkingIACT303 – INTI 2005 IACT303 – INTI 2005

World Wide NetworkingWorld Wide Networking

Network Infrastructure (social and Network Infrastructure (social and technical)technical)

The University of WollongongThe University of Wollongong

Objectives• In order to understand the issues that arise

from the internet and networking technologies you need to have an appreciation of what it actually is and how it works.

• This lecture is geared at giving you an understanding of how networking infrastructures and protocols work and evolve.

World Wide Networking Today

• In the year 2000, it was estimated that there were 300 million users of the internet, an uncountable number of local networks.

• Over time a number of networking technologies have emerged however one technology which has stood the test of time is TCP/IP.

• As many of you already know TCP/IP forms the basis of the Internet.

• It has been widely accepted by manufacturers of computing systems and operating systems. It is designed to be a platform neutral protocol - this is very different to some early networking technologies such as IBM SNA (Simple Network Access).

• TCP/IP is also an Open Protocol. It is not owned by any one person. It is a community effort governed by standards organisations such as the IEFT and IEEE.

The development of the Internet.

• The internet has demonstrated that Moore’s law is true i.e. hardware speeds double every 18 months.

– Since the 1980 interfaces such as Ethernet have improved efficiency from 6% to 90% on gigabit.

– Speeds of leased circuits has improved by a factor of 12,000.

– Number of hosts has increased by a factor of 50,000.

Who manages the Internet today?

• The internet evolved from ARPANET (DoD initiative).

• The Internet has always been an open effort between academic, government and private sector entities.

• As a result of this over the last decade because of the dependence of economies and social systems a number of organisations have emerged with the aim of controlling its technical direction.

• A number of organisations today control the following aspects of the Internet;

– Addressing and naming.

– Standards and Protocols.

– Users.

• A number of organisations today control the following aspects of the Internet;

– Addressing and naming. ICANN (Internet Corporation for Assigned Names and Numbers)

– Standards and Protocols. IETF (Internet Engineering Task Force)

– Users. ISOC (Internet Society)

• Addressing and Naming

ICANN (the Internet Corporation for Assigned Names and Numbers) is responsible for the control of domains i.e. .gov, .com etc and there delegations.

In addition to this they have defined protocols and standards for how IP numbers (addresses of nodes) are assigned to different networks around the globe.

You can visit there URL at www.icann.org

• Standards and ProtocolsThe IETF (Internet Engineering Task Force) overseas the development of standards and technical aspects of the Internet.

The IETF is an open forum which report to a sub committee.

Information about the IETF can be obtained by visiting www.ietf.org.

• UsersUsers of the internet need a voice and as a consequence a forum exists. The group is devising new applications of technology and generally developing awareness in the community of such infrastructure. More information can be obtained from www.isoc.org.

Internet Standards and Regulatory Bodies

• The technical development of the internet is regulated by ISOC and the IETF.

• Over the last couple of years a number of these organisations have been spending time fixing the mistakes of the past - this largely due to the changing applications, user base and economies of the internet.

• The technical activities of the internet community are documented in standards documents called RFC’s.

• RFC’s are Request for Comments.

• Protocols, standards and proposed changed typically end up being RFC’s. For example IPv6 has a number of RFC’s discussing its deployment and design.

• RFC’S exist to encourage debate (openness) and document practices.

• Normally RFC’s contain technical detail - however sometimes they present rationales, summaries or even introductions to standards/ protocols.

• Because the internet has been developed by a group of ‘Nuts/Nerds/Geeks’ a number of RFC’s exist which make a mockery of the process.

– RFC1149A standard for the Transmission of IP Datagram by Avian Carriers

– RFC2324Hypertext Coffee Pot Control Protocol (HTCPCP/1.0)

• RFC’s only become standards once the IETF board has ratified them ONLY after an exhaustive testing and analysis process.

The organisation of Internet Networking

Protocols.• Telecommunications is complex. Such

systems are complex devices which hundreds if not thousands of interactions.

• As a consequence of this complexity a number of techniques have been devised which help describe the process of defining networking standards and communication systems.

Communication system and distributed

computing.• Distributed computing is gaining popularity. It

is a subset of cooperative computing. Factors contributing to interest in this computing are;

– Technological advances in micro electronics are changing the price performance ratio in favour of multiple low cost, high perfomance systems.

– Interconnection and communication costs are falling.

– Users are demanding more economical, rapid, sophisticated and reliable facilities.

• Computing has always been about sharing resources - however for this to be done there needs to be a coordinated communications infrastructure.

• The problem with communications infrastructures is they tend to span national boundaries, are under the governance of many parties and are technically challenging to manage. The private sector is largely responsible for design and development and as a consequence controls are needed.

• In order to service this resource sharing a communications system must provide;

– naming and addressing schemes.– segmentation.– flow control.– synchronisation.– priority.– error control.

• Due to the complex interactions of the components in these systems standards organizations have developed models which describe how to best modularize these tasks.

Layered Communication Models• In the 70’s and 80’s a number of vendors

produced hardware for computing networking which could only work in homogenous computing environments and with particular kinds of equipments.

• Examples include IBM’s networking technologies such as SNA, Apples Appletalk and even DEC’s networking infrastructure.

• As a result a model was developed for communications which clearly articulated components of such system which could be modified within its parameters and have no effect on the remainder of the system.

• Layered models typically provide;

– independence.– flexibility.– standardisation.– simplified implementation and maintenance.

• The Department of Defenses networking model designed back in the 60’s.

• The layers of the OSI Model can be mapped back to this model. This model was initially used for NCP (the predecessor of TCP/IP).

Process/ Application

Host to Host

Internet

Network Access

• The model we are more accustom is the OSI model that is made of 7 layers.

Application

Presentation

Session

Transport

Network

Data Link

Physical

• The OSI model was designed by the ISO committee (International Standards Organisation).

• Even though it is portrayed as being widely accepted its was never implemented as a specific technical standard.

• Its function has been one of a model that has help technical people to communicate efficiently about different processes

• Here are the mapping of the DOD model to the OSI model.

Application

Presentation

Session

Transport

Network

Data Link

Physical

Process/ Application

Host to Host

Internet

Network Access

Department of Defences Model- DOD

Open Systems InterconnectModel - OSI

So how does all this relate to the Internet?

• Well the Internet is based on a number of core infrastructures which fit very nicely into the OSI model.

• The internet is based on TCP/IP - however TCP/IP is a protocol suite - that is a collection of protocols and standards that work together. Each of them has a RFC.

• The core technologies are:

– IP (Internet Protocol)Which provides addressing and routes packets from one node to another - RFC791.

– ICMP (Internet Control Messaging Protocol)Provides the IP protocol with error correction techniques and routing management - RFC792

– ARP (Address resolution protocol)Even though it isn’t part of TCP/IP it is essential - it can be used with other protocol stacks. This translates IP address to an actual hardware address. Largely used for local segments - RFC823.

– UDP (User Datagram Protocol) is a connectionless protocol which is similar to TCP. It is a ‘best effort’ transport for message. We see it largely used in streaming application - RFC768 and 793.

• The TCP/IP protocol suite can be related directly to the OSI Model.

ApplicationLayer

TransportLayer

NetworkLayer

LinkLayer

PhysicalLayer UTP, Copper, Fibre, Radio Waves

ARP, Device drivers

IP ICMP

TCP UDP

HTTP, FTP, LDAP Streaming, Halflife

• You will notice that some of the parts of TCP can span many layers for example ARP can also be found in the application layer along with ICMP.

• So why do we need to understand this;

– It forms the building blocks of the Internet.

– The internet is a complex system.– A number of complex protocols are used.– There are a number of bodies which

dictate direction.

Physical Layer: software and hardware programming that transfers the actual data

stream from one point to another

Data Link Layer: This is the layer where the protocols (yes, more of them) control the transfer of the data across the physical network (the cables). MAC Address's run at this level

Application Layer: the actual programs that you use to create the data to be transferred over the network

Presentation Layer: the data created by the programs above is "encoded", ready to be sent over the network

Session Layer: the layer that actually does the talking between the protocol that runs on the server (often as a program) and the protocol that runs on the network hardware (like a hub or switch).

Session Layer: A session is created over a virtual "port", which is the "location" where Layer 6 (presentation) talks to the Layer 4 (transport).

The Transport Layer makes sure the data is sent and received across the network correctly.  It packages, checks delivery and sends requests to redeliver when it isn't. 

Network Layer: addresses information packets by their Internet Protocol address and also controls the route of the message

Application Example: Email

Replace with IMAP (if you like)

Application Example: Email

Scenario: at home via a modem PPP I dial up

I get a dynamic IP addressFor the duration of my dial up

I check my email using imap4 And send it using smtp

Checking is done via a session negotiated over port 143 and sending over port 25

The email gets broken up into packets and routed thru The Internet