MIS140 - Exam 1
Transport
• Deals with end-to end issues such as segmenting the message for network transport, and maintaining the logical connections between sender and receiver. • Links application layer to the network with end to end connections. • Network address translation • Breaks long messages into packets • Ensures packet delivery and flow control
Physical
• Defines how individual bits are formatted to be transmitted through the network • Actually move bits
Media Access Control
AKA MAC, controls the flow of information by using ACKS for good packet or NAKs for bad packet, which require retransmission. Such as stop and wait ARQ or contineous ARQ
You decide to create your own protocol for Data Link Layer. Define the fields necessary for your protcol
Data Start Length Destination Address Control EDV Vlan Source Address
Give a specific example of 'header' information that would be optional in a HTTP request/response cycle
Date: Sept. 27, 2012 Server Information: Apache 2.2 URL: http://www.yahoo.com Content Type: Text/HTML
Data Link
Deals with message delineation, error control, and network medium access control.
Presentation
Formats data for presentation to the user. Provides data interfaces, data compression and translation between different data formats. Encryption/decryption
Give a specific example of 'header' information that would be required in a HTTP request/response cycle
HTTP version: version 1.1 Status Code: 202 Response: Ok
Message delineation
Indicates when the message starts and stops. Also contains EDV for errors, source address, and other functions in the frame.
Presentation
Name the layer where SSL encryption occurs
Transport
Name the layer where ensuring end to end reliable packet delivery occurs
Data Link
Name the layer where media access control occurs
Application
Name the layer where message creation occurs
Data Link
Name the layer where message delineation occurs
Physical
Name the layer where moving bits occurs
Physical
Name the layer where multiplexing occurs
Network
Name the layer where routing occurs
Transport
Name the layer where segmentation occurs
Session
Name the layer where the accounting occurs
Application
Provides a set of utilities used by application programs. Create, send, and respond to messages. Network monitoring and management.
Session
Responsible for initiating, maintaining and terminating each logical session between sender and receiver. Session accounting and logging.
Network
Responsible for making routing decisions. Choose the best route through the network Identification of hardware layer address.
Assume that we are trying to multiplex three logical circuits onto a DS-0, or 64kbps, circuit. If our single criterion is to minimize data transmission time, which method, FDM, or TDM, would you recommend? Why?
TDM because FDM uses guardbands that take away from thecircuit and it is at 3 logical circuit, it allows more frequent time to switch back.
What six factors are used to select the most appropriate media for communication
Type of network Cost Transmission distance Security error rates Transmission speed.
Error control
contains EDV for checking for errors in the message by using mathematical calculations such as checksum. If a error is detected, the packet will retransmission.
In clean, error free, and interference free analog transmission, what three basic factors could be changed to obtain a higher data rate
increases wave/second decreases wave/symbol increases bit/symbol
