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802.1
Is one of the IEEE standards for LANs and MANs which gives the introduction to the set of standards and defines the interface primitives.
802.2
The standard describes the upper part of the datalink layer and uses the Logical Link Control(LCC) protocol.
802.3
Is a IEEE standard called CSMA/CD for LANs. Uses the Ethernet cabling (10Base5 indicates 10Mbps, uses baseband signalling and can support segments upto 500 meters) also called thick ethernet which are coaxial cables with markings at every 2.5 meters to show where the taps go and are connected by the Vampire taps. Other types of cablings include 10Base2, called thin ethernet which can handle 30 terminals per cable segment and are connected by BNC connectors. Both these methods require time domain reflectometry to detect the breaks in the cable. Another cable standard is 10BaseT also called twisted pair running into a central hub, connected by transceivers. This can run only upto 100 or 150 meters. The fourth cabling option is 10Base-F which uses the fibre optics.
802.4
LAN standard also called Token Bus.
802.5
LAN standard called Token Ring.
ALOHA
Aloha is the multiple access protocol devised by Norman Abramson to solve the channel allocation problem using the ground-based radio broadcasting and has two versions: pure which considers the time as continuous and slotted in which the time is devided into descrete slots into which all frames fit; this requires the global time synchronization.
ARPANET
ARPANET (Advanced Research Projects Agency) was sponsored by DoD (U.S. Department of Defense) which connected hundreds of Universities and government organizations using leased telephone lines. With the advent of satellites and radio networks, the existing protocols had trouble interworking with them, a new reference model TCP/IP with the ability to connect to multiple networks together in a seamless way as the main goal was proposed and named after its two primary protocols.
ATM
Asynchronous Transfer Mode is the technology that makes Broadband Integrated Services Digital Network (ISDN) offer video on demand, live television from many sources, full motion multimedia electronic mail, CD-quality music, LAN inter connection, high speed data transport for science and industry and many other services that have not been thought of, all over the telephone line.
Backbone
Backbones are the fast routers connected by high-bandwidth lines on which the LANs are built.
Broadcasting
Sending a packet to all destinations simultaneously is called broadcasting.
Collision-Free Protocols
The two protocols devised to send the data in an contention free manner in MAC sublayer are: bitmap method, where a N bit contention period is begun each time the transmission of all the N stations end in which they reserve their time slot and binary countdown where the stations send their addresses in binary form which are ORed together to get the station with the highest address which ultimately gets the channel.
Congestion Control
The congestion control algorithms can be devided into two groups: open loop and close loop. Open loop solutions attempt to solve the problem by good design by making sure the congestion does not occur in the first place. Open loop algorithms are also divided into that act at source versus ones that act at destination. Closed loop solutions are based on the feedback loop. Closed loop algorithms are also divided into two subcatagories: explicit feedback and implicit feedback. Some congestions control algorithms are traffic shaping, Leaky bucket, Token bucket, Flow specification (all openloop). The close loop algorithms are: Admission control, Choke packets, Weighted fair queuing, Hop-by-Hop choke packets, Load shedding
Contention
Systems in which the multiple users share a common channel in a way that can lead to conflicts are called contention systems.
CRC
Cyclic Redundancy Code (Polynomial code) is a way to remove the errors in a frame by considering the bit string as representations of polynomials with co-efficients of 0 and 1 only.
CSMA Protocols
Career sense multiple access protocols suite consists of persistent and nonpersistent CSMA
Datagram Service
The unreliable connectionless service is called datagram service.
DQDB
DQDB is Distributed Queue Dual Bus, a standard used in MAN and is denoted by 802.6 in IEEE standards.
Fragmentaion
When data packet is to be moved inbetween two or more different netrowks, each network may impose some restriction on the maximum size of the data that can be sent through that network due to a number of regions as hardware, OS, protocols, compilance with internal standards, desire to reduce transmission errors, desire to prevent one packet from occupying the channel for a long time.
Frame
Frame is the collection of data bits from physical layer well demarkated by some rule to form a unit of data transmission in data link layer. Frames is the basic way to check errors in the data transmission.
Functions of Layers
Application Layer: Is concerned with the terminals. An abstract Network Virtual Terminal is defined that editors and other programs can be written to deal with, where a peice of software is written to map the functions of the network virtual terminal onto the real terminal. Other functions of application layers include file transfer, electronic mail, remote job entry, directory lookup and various other general purpose & special purpose facilites.
Presentation Layer: Is concerned with the syntax and semantics of the information transmitted, encoding of data, deals with the exchange of data representation such as ASCII and Unicode.
Session Layer: Remote log in, file transfer, token management, synchronization.
Transport Layer: accept data from the session layer and split it into small pieces and send those to network layer and ensure the correct arrival at the other end. Making multiplexing transparent to session layer. Transport layer header tells which message belongs to which layer?. Flow control.
Network layer: Is concerned with the operation of the network, how the packets are routed from one machine to other, congestion control, billing information, handling of problems occuring due to heterogeneous networks.
Datalink Layer: create and recognize the frame boundaries, handling the problems of duplicate frames, flow control, buffer space management, control the access to a shared channel.
Physical Layer: Actual transmission of data, how many volts should be used to represent 1 and 0, how many microseconds a bit should last, how the initial connection is established & how it's torn, how many pins the network connector should have.
Interface
The primitive operations and services the lower layer offers to upper layer.
Internet
Internet is network of networks connected by black boxes called repeaters which copy individual bits between cable segments, Bridges store and froward data link frames between LANs, Mulitprotocol routers forward packets between dissimilar networks, Transport gateways connect byte streams in the transport layer, Application gateways allow interworking on networks. Conventionally gateway is used to mean a device that connects two or more dissimilar networks.
IP Address
Each IP packet will contain IP addresses of both the source and destination. Each address is of 32 bytes and are devided into five classes A, B, C, D, E. Each host on the network will have its unique network number provided by the NIC (Network Information Center). The IP address 0 means this network or this host and -1 is used for broadcast addresses to mean all hosts on the indicated network. The network address 0.0.0.0 is used by hosts while booting but not afterwards.
Hamming Distance
The number of bit positions by which the two code words differ is called hamming distance. In another way the number of bits that need to be inverted in one code word so that it will represent its nearest or next code word is called hamming distance.
MAC
Medium Access Control is a sublayer of datalink layer, deals with the broadcast channels, sometimes refered to as multiaccess channels or random access channels.
Manchester Encoding
Manchester encoding is the way to represent the bits in a data frame such that it willn't produce any redundency in the bit transmissions in the physical layer.
Multicasting
Multicasting is sending messages to well-defined groups that are numerically large in size but small compared to the network as a whole.
Network architecture
A set of layers and protocols
Optimality Principle
It states that if router J is on the optimal path from router I to router K, then the optimal path from J to K also falls along the same route. The set of optimal routes from all sources to a given destination form a tree rooted at the destination, is called Sink Tree.
OSI
Open System Interconnection reference model is developed by Inernational Standards Organization to standardize the protocols used in various layers.
Pipelining
In Slinding window protocol suite, the goback n protocol causes the transmission of all the frames to the destination even if the acknowledgement for a previous frame hasn't been received yet, till the sender's window gets filled is called pipelining.
Port
Ports indicate which service is desired. port-23 is for Telnet, port-79 is for Finger, port-119 is for USENET news, etc.
Protocol stack
A list of protocols, one per layer in certain system.
Routing Algorithm
The main function of network layer is routing packets from the source machine to the destination machine.The routing algorithm is that part of the network layer S/W resposible for deciding which output line an incoming packet should be transmitted on. They can be grouped into two classes: Nonadaptive algorithm which don't base their routing decisions on measurements or estimates of the current traffic and topology. This is also called static routing. Adaptive algorithms change their routing divisions to reflect the changes in the topology, and usually the traffic as well. Static or Nonadaptive algorithms are Shortest Path Routing, Flooding, Selective Flooding, Flow-Based Routing. The adaptive algorithms are Distance Vector Routing algorithm, Link State Routing.
Simplex Protocol
The simplest protocol in data link layer where data is transmitted in only one direction with the assumption that the sending and receiving networks are always ready, ignoring the processing time, having infinite buffer space and the communication channel between the data link layers never damages or looses the frames.
Sliding Window Protocol
The goal of the protocol suite is to maximize the use of bandwidth through a technique called piggibacking where the outgoing acknowledgement is temporarily delayed so that they can be hooked on to next outgoing data frame.
SNA
System Network Architecture, as seven layer protocol designed by IBM.
Stop and Wait Protocol
Is equivalent to Simplex Protocol with the restriction that buffer space is limited.
Traffic Shaping
The open loop method to manage congestion is forcing the packets to transmit in more predictable way. This approach widely used in ATM networks is called traffic shaping. Monitoring the traffic flow is called traffic policing.
Tunneling
Tunneling is defined as a way of sending data packet of a network to the destination network following the same protocol, through a network inbetween, which follows a different protocol, by wrapping the data packet in the payload field of the network inbetween.
Protocol Acronyms
 
QUESTIONS

1. All the network classes are present in ________ class.
2. TCP/IP stands for __________________
3. ______________ are fire-and-forget bundles of information that are passed over the network.
4. _________ are more specifically TCP/IP connections, used to implement reliable bi-directional point-to-point, stream-based connections between hosts on the internet.
5. ____________ class is used to create client side sockets.
6. ______________ class is used to create server side sockets.
7. Socket class can be used to create a server socket (T/F)
8. Explain difference between socket and serversocket (SQ)
9. What is a URL (SQ)
10. The default HTTP port on any host is _________
11. HTML stands for _________________
12. Explain the various parts of this URL: http://www.example.com:80/
13. http stands for ______________
14. Error in a URL throws _______________ exception.
15. Network programs cannot be multithreaded (T/F)
16. DNS stands for ____________________
17. www stands for __________________
18. world wide web programming is not possible using network classes of java (T/F)
19. SMTP stands for __________________________
20. Even without a network connection we can test a java network program (T/F)
21. MIME stands for ___________________
22. Server socket waits for a client connection infinitely (T/F)
23. ___________ is the server socket method which waits for a client connection.


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