Internet Protocol Architecture Chapter 2. The Internet Internet evolved from ARPANET Developed in 1969 by the Advanced Research Projects Agency (ARPA)

Internet Protocol Architecture

Chapter 2

The Internet

Internet evolved from ARPANETDeveloped in 1969 by the Advanced

Research Projects Agency (ARPA) of the U.S. DOD

First operational packet networkPacket network also applied to tactical radio

& satellite nets need for interoperability led to standardized TCP/IP protocols

Internetworking standards was proposed by Vint Cerf and Bob Kahn (TCP/IP)

Key Elements

Hosts: computers, mainframes, workstations, etc.

Ethernet Switch: Connecting hosts in a LAN (multiple segments)

Routers: Connecting LANs and WANS

Each segment can be a separate building

Cisco's Catalyst Switch

http://www.querycat.com/question/f3d88ef267ad2505f6e7cfe3061aaca3

Key Elements

ISP (Internet service provider) Regional ISP Backbone ISP

CPE (customer premises equipment): modems, DSL, cable modem, satellite

NAP (network access point): One of the major elements connecting ISPs

Last mile (or local loop): physical path (infrastructure) between the host and the ISP – coax. Copper, etc.

POP (point of present): ISP site with communication equipments

NSP (network service provide): The company that provides backbone services to ISPs

http://navigators.com/internet_architecture.html

Internet Architecture

Internet Architecture

Example ConfigurationAssume -Company C, located in San Francisco,

-Has 5 hosts-Connected to an ISP Y

-David located in NY -Connected to ISP Z-Uses DSL

- Company A runs the NAP in West coastAnd company B runs the NAP in East Coast

-Peer agreement

Show: POPsCPERegional ISP

http://www.vtc.com/products/TCP/IP-for-Windows-tutorials.htm

Example ConfigurationAssume -Company C, located in San Francisco,

-Has 5 hosts-Connected to an ISP Y

-David located in NY -Connected to ISP Z-Uses DSL

- Company A runs the NAP in West coastAnd company B runs the NAP in East Coast

-Peer agreement Show: POPsCPERegional ISP

Network Protocols

Protocols define format, order of messages sent and received among network entities, and actions taken on message transmission

Set of rules or conventions that allow peer layers to communicate

Key features Syntax (format of the data) Semantics (Control information, error handling) Timing (sequencing and synchronization)

How Does a Protocol Work?

A human protocol and a computer network protocol:

Hi

Hi

Got thetime?

2:00

TCP connection request

TCP connectionresponseGet http://www.awl.com/kurose-ross

<file>time

Open Systems Interconnection - OSI

Developed by the International Organization for Standardization (ISO)

Has seven layers Is a theoretical

system delivered too late!

TCP/IP is the de facto standard

Peer layers communicate with one another

Open Systems Interconnection - OSI

TCP/IP Protocol Architecture

Developed by US Defense Advanced Research Project Agency (DARPA)

For ARPANET packet switched network

Used by the global Internet

Protocol suite comprises a large collection of standardized protocols

TCP/IP Layers

Application layer Host-to-host, or

transport layer Internet layer Network access layer Physical layer

Physical Layer Protocols Responsible for transporting the

information encapsulating information and

getting it ready for transportation Deals with physical interfaces,

electrical parameters, pin outs, number of twists per foot, cable gauge, data rate, signal integrity, etc.

Examples: RS-232, V.35, RJ-48, DS3, OC-n, High Speed Serial Interface

Physical Layer Protocols - Examples RS-233

Interfacing computer to modem Supports speeds up to 9.6 Kbps 25-pin or 9-pin interface

V.35 Serial interface between the

terminal and the digital communication equipment (T1)

Supports speeds above 19.2 Kbps RJ-48

Physical interface for T1 and E1 Defined by G.703 standards

DS3 Uses coaxial cable Supports 45 Mbps

OC-n Fiber optic interface n can be 1,3,12,etc. Multimode or single mode

High speed Serial Interface Supports 42 Mbps Interfacing ATM switches

Data Link Layer Protocols Frame and format information according to some

standards Two basic categories

Connection oriented Technology Establishing pre-defined virtual path upon request Many different virtual paths can reside on a physical link (like a

highway system) Example: ATM and Frame Relay Protocols

Connectionless Technology Only source and destination addresses are defined No pre-defined path exists between devices The actual routing path can be different depending on the network

status Example: High-level Data Link Control (HDLC)

Network Protocol Layers Transporting individual packets of information

through the network end-to-end Can route packets according to actual device

address or network topology (connectionless) Routing is done according to the network

manager or by a dynamic routing protocol Without Network layer all routings will be point-

to-point Examples:

Internet Protocol (IP) used on Internet Packet-based; Connectionless

IPX developed by Novel used in LAN Packet-based; Connectionless

Transport Protocol Layers Interfacing the upper layers to lower layers Formats applications into segments Examples: TCP and UDP Offers end-to-end flow TCP

Provides reliable delivery of data Keeps track of packet order

UDP User Datagram Protocol Does not guarantee delivery Offers faster data delivery

Application Layer

provide support for user applications need a separate module for each type of

application

TCP/IP Applications

Simple Mail Transfer Protocol (SMTP) Provides basic electronic mail Only sends (forwards) mail Uses TCP

File Transfer Protocol (FTP) Used to send files between systems – file transfer Uses TCP connect to check the ID and PW Establishes another TCP connection for data transfer

Telnet Provides remote login Implemented in two modules: User and Server

User Telnet: Interacts with terminal I/O module Makes the remote terminal appear as local terminal

TCP/IP Applications

Operation of TCP and IP

Addressing Requirements Two levels of addressing

required Each host on a subnet

needs a unique global network address called IP address

each application on a (multi-tasking) host needs a unique address within the host known as a port

Subnets: attached devicesDefined by the networkAccess Layer

Operation of TCP/IPProcess at A hands the message to TCP layer: Send the message to host B port 2

TCP hands the message to IP – destination will be Host B

IP hands it to network Layer -> next hop is router J

Conditions The signal format For the physical path

Operation of TCP/IP

Data from the applications software

Header contains: Destination port, sequence numberChecksum

Header contains: Destination of the host address

Header contains: Destination subnet address – which attached deviceFacility request: e.g., priority

Transmission Control Protocol (TCP) Standard transport layer for Internet is (TCP) Provides a reliable connection for transfer of

data between applications A TCP segment is the basic protocol unit

Logical connection between peer layers TCP provides host-to-host connection (port-to-port)

TCP tracks segments between entities for duration of each connection Segment flow

TCP Header

User Datagram Protocol(UDP) An alternative to TCP No guaranteed delivery No preservation of sequence No protection against duplication Minimum overhead Adds port addressing to IP

That is why we need it!

UDP Header

IP Protocol IPv4

Addresses are 32 bits wide Its header is 20 bytes at minimum Uses doted-decimal notation (e.g. 43.23.43.56)

IPv6 Provides larger address domain; addresses are 128

bits wide Multiple separate headers are supported Handles audio and video; providing high quality paths Supports unicast, multicast, anycast

IP Header

IPv6 Header

OSI - review Open Systems Interconnection developed by the International

Organization for Standardization (ISO)

has seven layers is a theoretical system

delivered too late! TCP/IP is the de facto

standard

Standardized Protocol Architectures

Each layer must interacts with threeOther layers

Protocols define which services are Provided

Providing services to N+1Multiple services: Each service has an address: Called Service access Point

Service Primitives and Parameters

Adjacent layers provide services to one another:

Primitives to specify function performed

Parameters to pass data and control info

N N-1 N-1 N

Elastic and Inelastic Traffic Elastic traffic

can adjust to delay & throughput changes over a wide range

eg. traditional “data” style TCP/IP traffic Inelastic traffic

does not adapt to such changeseg. “real-time” voice & video trafficneed minimum delay requirements

General Traffic Characteristics

Throughput Amount of data carried over time

Delay Time it take to deliver data between hosts

Delay Variation Variation in the time when delivering the data

Packet Loss Packets not made it to the destination

Media Types

Text, Audio, Graphic, and Video Different technologies are required to support

various media types Examples of multimedia technologies

Compression: JPG for images, MPG for video Transmission and networking technologies Protocols: RTP (real-time transport protocol) Quality of service (QoS) – providing different levels of

services to different applications

Watch this: http://www.vtc.com/products/TCP/IP-for-Windows-tuto

rials.htm

TCP/IP Applet http://www.kom.e-technik.tu-darmstadt.de/projects/ite

ach/itbeankit/Applets/TCP/tcp.html

Simple TCP/IP Lab http://www.windowsnetworking.com/articles_tutorials/t

sttcpip.html?printversion