Cs 2600 Week 3-4

Front 1

OSI Network Model Layers

Back 1

• Application
• Presentation
• Session
• Transport
• Network
• Data Link
• Physical

Front 2

TCP/IP Network Model Layers

Back 2

• Application
• Transport
• Internet
• Network Interface

Front 3

OSI Mnemonic

Back 3

"All People Seem To Need Data Processing”

Front 4

Data Communication Protocol

Back 4

A set of rules governing and standardizing communication between computers.

Front 5

Protocol Specification

Back 5

Defines how a particular layer operates

Front 6

Protocol Implementation

Back 6

The actual system (hardware or software) that implements a protocol specification

Front 7

Service Interface

Back 7

A set of definitions that define how a protocol layer obtains services from the layer below.

Front 8

Service Interface Definitions

Back 8

• Appear similar to methods
  
• Has parameters and are procedural
  

send (data buffer, length, destination addr)

Front 9

Peer-to-Peer Interface

Back 9

• A definition for a data structure
  
• Defines the messages that two peers exchange
  

Front 10

Data Definition Example

Back 10

Front 11

Service-Peer Interface Relation

Back 11

Front 12

RRP

Back 12

Request/Reply Protocol

Front 13

HHP

Back 13

Host-to-Host Protocol

Front 14

MSP

Back 14

Message Stream Protocol

Front 15

Demultiplexing Key

Back 15

A standardized code in a header (at any layer) that tells the protocol layer reading that header which upper layer to pass the contents of its message to.

Front 16

Second Principle of Network Design

Back 16

Data originating in a given layer, along with that layer's header, is viewed as "data" by the protocol below.

This process is called encapsulation.

Front 17

Encapsulation Diagram

Back 17

Front 18

Orgs involved with OSI Standards

Back 18

ISO

• ANSI (IBM, Xerox, Others)
  
• IEEE
  
• NIST
  
• EIA/TIA
  
• ITU
  

Front 19

Orgs involved with TCP/IP Model

Back 19

IETF

• DoD
  
• Unix (At&T)
  
• Universities
  
• Small Manufactures
  

Front 20

Application Layer (TCP/IP)

Back 20

Web, Email, Gaming, Video data

Front 21

Transport Layer (TCP/IP)

Back 21

• Provides end-to-end logical channels for apps to locate each other
• TCP (more reliable) or UDP
  

Front 22

Internet Layer (TCP/IP)

Back 22

• Uses IP Protocol
  
• Handles end-to-end routing across the Internet
  
• Connects dissimilar networks
  

Front 23

Network Interface Layer (TCP/IP)

Back 23

• All underlying hardware and network-specific tech
  
• Technically outside the scope of Internet Architecture
  
• 3G/4G, Ethernet, WiFi
  

Front 24

Application Layer (OSI)

Back 24

• Provides network services to applications
  
• File Transfer, Directory Services, Email Delivery
  

Front 25

Presentation Layer (OSI)

Back 25

• Formats data for presentation to user
  
• Includes standards for representation (char. sets, formatting), compression, and encryption
  

Front 26

Session Layer (OSI)

Back 26

• Provides reliability for app-to-app sessions
  
• Checkpointing and restart tools
  
• Not well understood/defined
  

Front 27

Transport Layer (OSI)

Back 27

• Handles process-to-process channel functions
  
• Adds reliability and connection management
  
• Lowest hardware-independent layer
  

Front 28

Network Layer (OSI)

Back 28

• Handles switching over a single network
  
• Data structure is a "packet"
  

Front 29

Data Link Layer (OSI)

Back 29

• Handles switching over a single link (between two nodes)
  
• Data structure is a "frame"
  

Front 30

Physical Layer (OSI)

Back 30

Hardware that transfers signals across a medium.

Front 31

Internet Model Standards Dev Process

Back 31

• Suggest protocol at IETF meetings
  
• Draft standard (RFC) in small group
  
• Seek Consensus via voting
  
• Design implementations of protocol
  
• Testing of spec/implementation
  
• Revision/Official Submission

Front 32

Bandwidth

Back 32

• Number of bits that can be transmitted on a link in some unit of time
  
• Measured in bits per second on network (bps)
  
• Bytes per second on a computer's bus (Bps)

Front 33

millisecond

Back 33

ms, 0.001 or 10^-3

WAN

Front 34

microsecond

Back 34

us, 0.000001 or 10^-6

LAN

Front 35

nanosecond

Back 35

ns, 0.000000001or 10^-9

Processing in a computer

Front 36

picosecond

Back 36

ps, 0.000000000001 or 10^-12

Front 37

Time to transmit 1 bit

Back 37

1

data rate

Front 38

Serial

Back 38

Bits sent through a single line one-by-one

Front 39

Parallel

Back 39

• Bytes sent over multiple lines simultaneously.
  
• Data inside computer bus typically sent this way
  

Front 40

Networks typically use ____________ communication systems

Back 40

Serial

Front 41

Bits transmitted at a particular bandwidth have __________________________.

Back 41

a particular width per bit.

Front 42

Factors that affect frame transmission time

Back 42

Smaller frame -> Slower Data Rate

Larger frame -> Faster Data Rate

Front 43

Latency

Back 43

• Amount of time that it takes a single bit to cross a link or entire network
  
• Longer distance -> Longer Latency
  

Front 44

Latency is affected by __________

Back 44

• the media over which data is traveling
  
• less impact than distance
  

Front 45

RTT

Back 45

• Round Trip Time
  
• Latency * 2
  

Front 46

If there's a slow network, we ask _______________________?

Back 46

• "Where is the bottleneck?"
  
• Which elements in the network are causing significant delay?
  

Front 47

Total Latency Formula

Back 47

Total Latency = Propagation Time + Transmission Time + Queuing Time

Front 48

Transmission Time

Back 48

Time to send data "out the door"

Message Size

Data Rate

Front 49

Propagation Time

Back 49

Time to travel across the medium on a single link.

Distance

Speed of Medium

Front 50

Queuing Delay

Back 50

Delay caused by the time a packet/frame takes for processing (or waiting to be processed) in computers, switches, routers, and servers

Amount of competing traffic

Processing power of nodes

Front 51

Delay x Bandwidth Product

Back 51

• The amount of data needed to fill the entire link
  
• If link is a pipe, this is the "volume"
  

Front 52

For this class, we use calculations of __________ instead of ____________ to measure data size.

Back 52

Powers of Ten (1 KB = 10^3) instead of Powers of Two (1 KiB = 2^10)