CS422
Week 1 (08/25/03 to 08/29/03)
Lecture on
Monday, 08/25/03
Add yourself to mailing list:
- Login to lore.cs.purdue.edu using your CS accoun
- Type “mailer add me to cs422-pso<#>”
- # = Your PSO Section number
- Eg. mailer add me to cs422-pso2
Grade Distribution:
- 50% Projects
- 50% Midterm and Final exam
- Late policy: 5% penalty per day, up to 7 days
- You cannot turning later than 7 days after due date
- 1% extra for writing notes – signup sheet will be bought to class next
week
Topics that will be cover:
Low level details:
- Signals & Media
- Digital Vs. Analog
- Synchronous vs. Asynchronous communication
- Modulation
- Bandwidth, throughput and noise
- Time & frequency multiplexing
Packet Transmission :
- Frames
- Error detection techniques
- LAN/WAN topologies
- Bus topology, CSMA/CD, CSMA/CA
- Ethernet hubs
- FDDI, ATM, ADSL
- Repeaters, bridges, switches
- Routing algorithm (Distance vector, link state)
Internetworking :
- Protocol layering
- IP Addressing
- APP
- IP Fragmentation & assembly
- TCP, Reliability, flow control, port demultiplexing
Applications :
- Socket API
- Client/Server concurrentcy
- TELNET, FTP, HTTP, CGI
- RPC, CORBA, Java RPC
- NFS, SMB, IPv6
Lecture on
Wednesday, 08/27/03
History of Internet
- Started in late 1960’s
- Department of defense (DoD) through advance research project agency
(ARPA) created a network to link different research centers
- Since computers were expensive, instead of giving a computer to every
university, a few computers were shared using a network (ARPA-NET)
- Main use of this network was remote access (TELNET)
- After telnet, the next most popular application that used the network
was E-mail
- The research on the internet continues in the 1970’s and 1980’s
- Internet becomes a commercial success in the 1990's
- Internet has been doubling in size every 9-12 months!
What is a network?
- A group of inter-connected computers
- Uses of a network:
- Remote access to a computer
- Remote file access:
- FTP (File transfer protocol)
- NFS (Network file system – Used on UNIX)
- SMB ("samba", used in Windows)
- HTTP (Hyper text transfer protocol – Used on Internet
- Distributed computing:
- Multiple computers working on the same projects/problem simultaneously.
- Eg. (1) Cluster computing: A group of inexpensive machines are connected
through a fast network like Ethernet. Google distributes its search query
among multiple machines
- Eg. (2) Rendering farms: Render frames in a computer generated picture
- Eg. (3) SETI (Search for extra-terrestrial intelligence) Project:
People donate idle CPU cycles to analyze radio telescope data
Basic tools to test the network:
- Ping:
- Usage in windows: ping <host>
- Tells if the machine is alive or not by sending an ICMP (Internet
control Message Protocol)
- In solaris, PING program is located in /usr/sbin/ping
- Tracert
- Usage in windows: tracert <host>
- Lists the intermediate routers needed to reach a destination host
- Tracert is not perfect, since routes may change. However, this
does not happen too often
- In solaris, this program is located in /usr/etc/traceroute
- IPConfig
- Lists the network interfaces and IP Addresses in your computer
- In solaris, this program is located in /use/sbin/ipconfig –a
Lecture 3 on
Friday, 08/29/03
Forms of energy used for transmissions:
- Electricity
- Radio
- Light – Laser & Infrared
- Sound
Media used for transmission
- Copper wire
- Other metals like gold, platinum, etc are used, but less frequently
because they are expensive
- Coaxial cable: Cable is in center with protection around it to prevent
noise from entering the cable
- Twisted pair: To reduce electro-magnetic noise. Coaxial cables are
more expensive, but have better resistance to noise
- Transmission speed in copper wire is 0.7c (c = speed of light = 3
* 108 m/s)
- Radio waves
- Also called radio frequency (RF)
- Uses electro-magnetic waves
- Different frequencies used by different channels
- Frequency spectrum of each channel is limited
Each channel has a position in the spectrum, and a bandwidth
- Wide bandwidth implies more information is transmitted. For example,
to transmit voice, 3hz is enough, but images need more bandwidth
- RF can be used with satellites
- Two types of satellites
- GEO (Geo-stationary Earth Orbit)
- Remain at the same point in sky
- They are about 36000Km (~ 20000miles) above Earth and around the
equator
- Limited to 40-45 satellites
- Long delay (~ 0.5 seconds)
- LEO (Low Earth orbit)
- Not in the equator
- 200-400 miles above Earth
- Rotates faster than Earth (Takes about 1.5 hours per revolution)
- Need an array of satellites to cover an area
- Microwave: Need a clear path
- Infrared light
- Laser and optical fibres: Expensive, but a lot of data can be sent
Important limits of transmission system:
- Propogation delay: Time required for signal to travel across the media.
Copper wire takes 0.7c
- Bandwidth: Maximum number of times per second that a signal can change.
Bandwidth limits the maximum throughput