Computer System Management - Networking (Physical Layer)

Amarjeet Singh

October 10, 2011

Partly adopted from Computer System Management Slides by Navpreet Singh Logistics

Timetable change reminder: Saturday is Friday timetable: Group 1 and 5 will have lab both on Friday and Saturday Next Lab Session: Half an hour visit to the IT server room to look at different networking devices Mini project : Has to be hands-on (learn a software tool or build something physical) Think beyond pure programming based project You will get enough of them in your 4 years at IIIT Delhi If you take up a topic on learning a tool then you should create an output that is somehow relevant to SM course More than one group allowed to take up a topic – only if too many students have taken up the same topic, I will not allow any more Mid sem exam papers – next class Revision…

What are two different types of client-server model

Comparing peer to peer model with client server modes Advantages? Disadvantages?

What are the different network topologies at the physical layer

Introduction to Computer Networks

The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions. Videos created in hypo-explanation last year: Ring topology: http://www.youtube.com/watch?v=Tf 4QayDsMkM Star topology: http://www.youtube.com/watch?v=qr qogmb59Aw Network Components

Physical Media Interconnecting Devices Computers Networking Software Applications Physical Media

Physical media can be defined simply as the means by which signals (data) are sent from one computer to another Wired (using a physical cable) - , Twisted pair, Coaxial - , WiFi, GPRS, 2G, 3G Interconnecting Devices

Connects multiple computers and other networking devices together using physical media

HUB, Switches, Routers, Wireless Access Points, Modems etc.

Multiple project groups on networking should discuss these in detail

Visit to server room during the lab sessions Interconnecting Devices

Difference between hub, switch and router – A video created as part of hypo explanation by last year SM students: http://www.youtube.com/watch?v=PwY15XBIi54 Networking Software

Protocols to setup the network configuration and define how the packets are to be transmitted Physical Media Physical Media Physical Media

Copper - Thick or Thin Unshielded Twisted Pair - CAT 3,4,5,5e&6 Multimode Singlemode Wireless Short Range Medium Range (Line of Sight) Satellite

Copper Media: Coaxial Cable

Coaxial cable: Copper-cored cable surrounded by heavy shielding and is used to connect computers in a network. Outer conductor shields the inner conductor from picking up stray signal from the air. High but lossy channel. Repeater is used to regenerate the weakened signals. Cable access - Data rate? Copper Media: Twisted Pair

Typically used in communications and most modern Ethernet networks A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs Two wires carry equal and opposite signal and receiver detects the difference (differential mode) Noise sources tend to effect both wires equally Two basic types - shielded twisted-pair (STP) and unshielded twisted-pair (UTP)

Unshielded Twisted Pair (UTP) Fiber Media

Two types of Fiber media : Multimode: less bandwidth (100 Mbps - 2 km; 1Gbps - 550 m) Singlemode: higher bandwidth (10 Gbps over more than 100 km)

QuickTime™ and a decompressor are needed to see this picture. Typical network architecture (wired) How web works?

Let's say you want to visit the google website. First you enter the address or URL of the website in your web browser. Then your browser requests the DNS Server to get the IP address of the web server How web works?

Then your machine sends an HTTP request to the web server that hosts the google site. The server sends the data over the Internet to your computer. Your web browser interprets the data, displaying it on your computer screen. Internet connections

ISP ISP network network

Typical Bandwidth? Backbone networks

ISP network . Customers connect to an ISP . ISPs connect to backbone

Customer Networks Map of internet connections

net, ca, us com, org mil, gov, edu jp, cn, tw, au de, uk, it, pl, fr br, kr, nl unknown

Source: OPTE Project (http://www.opte.org/maps/)

Graph Generate: Jan 15, 2005 Service provider network - Reliance

80,000 Kms of Fiber Connecting more than 1100 towns and cities Reliance Globalcom global network Internet naming hierarchy

The silent dot at the end of all addresses

.com .net .org .in

As of June 2009, there are 20 generic Top Level Domains (gTLDs) and 248 country code .tcd .ac .co Top Level Domains (ccTLDs) .iiitd www www DNS operation

A DNS server maintains the name to IP address mapping of the domain for which it is the name server The DNS server for a domain is registered with the domain registrar and the entry is maintained by the Internet Root-Servers (13, named alphabetically from A-M) or Country Level Root-Servers DNS operation

Whenever a server is queried, if doesn’t have the answer, the root servers are contacted. The root servers refer to the DNS server for that domain (in case the domain is a top level domain) or the Country Root Server (in case the domain is country level domain). Journey of a Data Packet

Video created as part of hypo-explanation in SM course last year: http://www.youtube.com/watch?v=u0a4Bh19i2Y Learning Today

Give me a short note on what you learned today