CSC645/745

We're gona ACE this quiz and the rest of the quizzes! :p

=Quiz 1 Review=

Question 1 - Define networking terms
'''1. Define the following terms: protocol, network, network structure, internetwork, network architecture, protocol hierarchy, layer, level-n protocol, level n-1 interface, physical medium, service primitives. '''


 * Protocol: A protocol defines the format and the order of messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or receipt of a message or other event. It defines peer-to-peer communications.
 * Network:  1 distributed system where communications are connected, means to transfer messages (data) between components in a single distributed system
 * Network Structure:	How components are physically connected. Example media: twisted pair wire, fiber optic cable, microwave channel. Two flavors: Point-to-point and multiple access
 * Internetwork: Take any networks of any sort and combine it to become bigger networks where routers are used to configure these networks. Means to transfer messages (data) between networks (i.e. between components in different distributed systems). A specific set of networks connected by routers that are configured to pass traffic among any computers attached to networks in the set. Most internets use TCP/IP protocols.
 * Network architecture: The design of a computer network. A set of layers and corresponding protocols
 * Protocol hierarchy: We have different layers on top of the physical media for the client and server that are connected via peer to peer protocols.
 * Layer: Well defined collection of functions. Run-time entities perform the functions defined by each layer.
 * Level-n protocol:
 * Level n-1 interface:
 * Physical medium:
 * Service primitives:

Question 2 - point-to-point vs. multiple access
'''2. What is the difference between point-to-point and multiple access networks? '''


 * Point-to-Point Networks:
 * A collection of links that are connected by nodes.
 * Able to send a transmition (data) from links to links from the source to the destination
 * Developed in 1960s~1970s
 * OSI/ISO standards
 * Have dedicated links between pairs of components.
 * Types: star, ring, tree, complete, irregular (most common)-> Impossible to do math analysis. Least discussed
 * ISSUE: Network topology (which pairs of components have links)
 * Multiple access networks:
 * Single shared communication channel
 * Types: Satellite/radio, ethernet, token ring
 * Ethernet: more for LAN. 1 to aparnet and 1 connected to ethernet
 * ARPANET: connection out of the network in Europe
 * TCP/IP Protocols
 * ISSUE: Channel allocation (who's turn it is to use the media).

Question 3 - internetwork vs. network
'''3. How is an internetwork different from a network? Why are both necessary? '''
 * Internetwork
 * Consists of various kinds of networks but connected using a router.
 * Uses the TCP/IP
 * Not ISO protocols.
 * Last 10yrs are ISO compliants.
 * Means to transfer messages (data) between networks (i.e. between components in different distributed systems). A set of networks connected by routers that are configured to pass traffic among any computers attached to networks in the set. Most internets use TCP/IP protocols.
 * Network:
 * A single distributed system where communications are connected.
 * means to transfer messages (data) between components in a single distributed system


 * why both are necessary
 * An internetworks allows for communication between two or more networks that can be of different infrustructures. It also allows for LANs to become WANs.

Question 4 - level n-1 interfaces
'''4. Why don't network architectures specify the level n-1 interfaces? '''

The network architectures do not specify the level n-1 interfaces because these are not visible "outside" of the computer executing the protocol code.

Question 5 - communication between levels
'''5.	Why isn't communication between peers on different levels allowed? '''

Communication isn't allowed between peers on different levels to avoid the mix up of code (spaghetti code). Make the programming for each level a much simplier task for the programmer and to allow each level to work more efficiently.

Each of the layer in the architecture have a peer-to-peer protocol to communicate with the same layer level. Each of this layers have APIs and interfaces that separates them. A change on a lower level of the network stack should not affect the APIs that are defined higher and thus does not need the developer to rewrite the calls to the APIs. The change should be seemless.

Question 6 - purpose of the interface control information
'''6.	What is the purpose of the interface control information added by the level n entity. Does this information get delivered to the remote level-n peer? '''

Question 7 - purpose of the header information
'''7.	What is the purpose of the header information added by the level n entity? Does this information get delivered to the remote level n peer? '''

Question 8 - level N PDU and the level N+1 PDU
'''8.	What is the relationship between the level N PDU and the level N+1 PDU? '''

Question 9 - Protocol
'''9.	What is a protocol? How is it defined? '''

A protocol is defined by the format of messages exchanged and the legal exchange of sequences. It defines peer-to-peer communication, logical description of what the peer is doing.

Question 10 - 4 classes of service primitives
'''10.	What are the four classes of service primitives? '''
 * 1) Request a service
 * 2) Indicate that request has arrived
 * 3) give Response to request
 * 4) Confirm that request arrived

Question 11 - service primitives and ISO/OSI standards
'''11.	How are service primitives used in the ISO/OSI standards? '''

Question 12 - confirmed message delivery vs. unconfirmed message delivery
'''12.	What is the difference between confirmed message delivery and unconfirmed message delivery? '''


 * Confirmed Message Delivery
 * Request + Indication + Response + Confirmation


 * Unconfirmed Message Delivery
 * Request + Indication

Question 13 - sequence of service primitives for delivery of confirmed message
'''13.	Describe the sequence of service primitives used to implement delivery of a confirmed message. '''

A picture paints a thousand words ;)



Question 14 - sequence of service primitives for delivery of unconfirmed message
'''14.	Describe the sequence of service primitives used to implement delivery of an unconfirmed message. '''

Another 10,000 words ;)



Question 15 - ISO/OSI Layers
'''15.	What are the seven ISO/OSI layers? Give a one sentence description of each layer. '''

"All People Seem To Need Data Processing." :p remember that sentence.


 * 1) Physical Layer: Transmission of bits on a single link.
 * 2) Data Link Layer: Error free transmission of packets on a single link
 * 3) Network Layer: End-to-End transmission of packets
 * 4) Transport Layer: End-to-End delivery of messages flow control
 * 5) Session Layer: Setup and manage end-to-end conversation between users, provide enhance data transport and dialog control
 * 6) Presentation Layer: Control syntax and semantics of information transmitted
 * 7) Application Layer: High level user services as well as high level generic services

Question 16 - Physical Layer
'''16.	Describe the major functions of the ISO/OSI physical layer. '''

Transmission of bits on a single link.

Question 17 - Data Link Layer
'''17.	Describe the major functions of the ISO/OSI data link layer. '''

Error free transmission of packets on a single link (flow control, line coordination).

Question 18 - Network Layer
'''18.	Describe the major functions of the ISO/OSI network layer. '''

End-to-End transmission of packets (subnet control, routing, congestion control, accoounting, network interface/gateway).

Question 19 - Transport Layer
'''19.	Describe the major functions of the ISO/OSI transport layer. '''

End-to-End delivery of messages (manage communication bit pipes between process) flow control.

Question 20 - Session Layer
'''20.	Describe the major functions of the ISO/OSI session layer. '''

Setup and manage end-to-end conversation between users, provide enhance data transport and dialog control.

Question 21 - Presentation Layer
21.	Describe the major functions of the ISO/OSI presentation layer.

Control syntax and semantics of information transmitted (formatting, compression, encryption).

Question 22 - Application Layer
'''22.	Describe the major functions of the ISO/OSI application layer. '''

High level user services (virtual terminals, file transfer, email, etc) as well as high level generic services (remote operations, reliable delivery, etc).

Question 23 - TCP/IP Layers
'''23.	What are the four (five) TCP/IP layers? Give a one sentence description of each layer. '''
 * 1) Hardware Layer: Physical bit transport
 * 2) Hardware Interface Layer: Transmit datagrams over specific network using physical address to identify hosts
 * 3) Transport Layer: Provide communication from one machine to another.
 * 4) User Services Layer: Provide communication between users (processes).
 * 5) Application Layer: Choose style of tranport and transfer data. Messages of streams of data are exchanged between peers

Question 24 - Hardware Layer
24.	Describe the major functions of the TCP/IP hardware and hardware interface layers (0 and 1).

Question 25 - Transport Layer
'''25.	Describe the major functions of the TCP/IP transport (IP) layer. '''

Question 26 - User Services Layer
'''26.	Describe the major functions of the TCP/IP user services (TCP/UDP) layer. '''

Question 27 - Application Layer
'''27.	Describe the major functions of the TCP/IP application layer. Why is this layer usually not included as part of the TCP/IP protocol stack? '''

Question 28 - TCP/IP Layer Vs. ISO/OSI Layering
'''28.	How is TCP/IP layering different from ISO/OSI layering? '''
 * TCP/IP


 * ISO/OSI

Question 29 - connectionless vs. connection-oriented service
'''29.	What is the difference between connectionless and connection-oriented service? '''
 * Connectionless service	
 * No logical connection established between peers before data exchange.
 * Message may arrive in any order (may not arrive at all).
 * Difficult to account for network resource utilization.
 * Connection-oriented service
 * Peer entities set up logical connection before data transfer.
 * During data transfer, all messages are delivered in order (usually guranteed to be delivered).

Question 30 - Define "-plex" terms
30.	Define the following terms: full duplex, half duplex, simplex 
 * Full duplex	: Data transfer in both directions at the same time.
 * Half Duplex	: Data transfer is both directions, but only 1 direction at a time.
 * Simplex	: Data transfer in only 1 direction.

Question 31 - Protocols
'''31.	Which protocols of TCP/IP are connectionless? Connection-oriented? Which layers of the ISO/OSI protocol are connectionless? Connection-oriented? '''


 * TCP/IP
 * Connectionless
 * Hardware (Layer 0) -- Service must be provided or emulated
 * Hardware Interface (Layer 1) -- Service must be provided or emulated
 * Layer 2 IP & Friends (ARP, ICMP, RARP)
 * Layer 3 UDP


 * Connection-Oriented
 * Layer 3 TCP


 * ISO/OSI Protocol Layers
 * Connectionless
 * MAC Layer
 * LLC Layer (Pass through MAC)
 * Transport Layer (Pass through MAC)
 * Session Layer
 * Presentation Layer
 * Application Layer


 * Connection-Oriented
 * Physical Layer
 * Data Link Layer
 * Network Layer
 * LLC Layer (Pass through MAC)
 * Transport Layer (Pass through MAC)