Skills: noneConcepts: local area network, router, inter network, the TCP/IP layered software “stack”, layer functions, layer protocols, dumb versus smart networks

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TCP/IP from 10,000 feet

Where does this topic fit?

• Internet concepts– Applications– Technology– Implications

• Internet skills– Application development– Content creation– User skills

TCP/IP from the outside

Application Program, forexample, a Web client

Application Program, forExample, aWeb server

A TCP/IP network

Local area networks

LAN LAN

A router at the edge

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From LAN to Internet to LAN

The Internet a network of networks

The path between two hosts

Crossing the LAN

LAN

R

From the LAN to the ISP’s router

Forward to next network

Forward to next network

Forward to next network

Reaches the destination network

Client Server

Delivered by the data link layer

A router goes down

Net routes around problems

TCP/IP, the very big picture

Layer Function

Application programs Do useful work like Web browsing, email, and file transfer

TCP/IP communication software

Handle communication between the client and server

Function of each layer

Layer Function

Application Do useful work like Web browsing, email, and file transfer

Transport Transport data between application programs running on two hosts

Internet Route packets between networks (inter network)

Data link Send data within the local area network

Physical Specify hardware characteristics and ways to differentiate between ones and zeros

Function of each layer

Layer Function

Application Do useful work like Web browsing, email, and file transfer

Transport Transport data between application programs running on two hosts

Internet Route packets between networks (inter network)

Data link Send data within the local area network

Physical Specify hardware characteristics and ways to differentiate between ones and zeros

Function of each layer

Layer Function

Application Do useful work like Web browsing, email, and file transfer

Transport Transport data between application programs running on two hosts

Internet Route packets between networks (inter network)

Data link Send data within the local area network

Physical Specify hardware characteristics and ways to differentiate between ones and zeros

Transport layer protocols

TCP (transmission control protocol)or

UDP (universal datagram protocol)

Data link layer protocols

Ethernet or

Wifi

Ethernet or

Wifi

Internet layer protocol

IP (the internet protocol)

Application layer protocols

Different protocols for each application

Different protocols for each application

Physical layer standards

or

Protocols at each layer

Layer Protocol

Application Many depending upon the application

Transport TCP or UDP

Internet IP

Data link Ethernet and WiFi most common

Physical Many wireless, copper wire, optical fiber, etc.

By design, the Internet is dumb

The Internet The telephone network

The telephone network is smart

Summary

Layer Function

Application Do useful work like Web browsing, email, and file transfer

Transport Transport data between application programs running on two hosts

Internet Route packets between networks (inter network)

Data link Send data within the local area network

Physical Specify hardware characteristics and ways to differentiate between ones and zeros

Self-study questions

1. Do you have a LAN at home? How many computers connect to it

2. There is only one connection leading out from your home router – where does it forward packets to?

3. When you connect to the Internet using a mobile device like a phone or a tablet, are you connecting to a network that is connected to the Internet? Explain.

4. We saw that there were two commonly protocols at the transport layer – TCP for reliable communication and UDP for fast, but unreliable communication. Which would an application programmer use for a file-transfer program? Which would an application programmer use for a streaming video program? Explain your answers.

Application

Physical

Do you recall the names of the TCP/IP protocol layers?

Do you recall the functions of the software at each layer?

Application:

Transport:

Internet:

Data link:

Physical:

Do you recall the protocol(s) used at each layer?

Application:

Transport:

Internet:

Data link:

Physical:

Resources