Internet Protocol Architecture Chapter 2

The Internet Internet evolved from ARPANET  Developed in 1969 by the Advanced Research Projects Agency (ARPA) of the U.S. DOD  First operational packet network  Packet 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

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

Internet Architecture

Example Configuration Assume -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 coast And company B runs the NAP in East Coast -Peer agreement Show: POPs CPE Regional ISP

Example Configuration Assume -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 coast And company B runs the NAP in East Coast -Peer agreement Show: POPs CPE Regional 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 Got the time? 2:00 TCP connection request TCP connection response Get 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 devices Defined by the network Access Layer

Operation of TCP/IP Process 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 number Checksum Header contains: Destination of the host address Header contains: Destination subnet address – which attached device Facility 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 ) 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 three Other layers Protocols define which services are Provided Providing services to N+1 Multiple 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 NN-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 changes  eg. “real-time” voice & video traffic  need 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:  tutorials.htm tutorials.htm TCP/IP Applet  darmstadt.de/projects/iteach/itbeankit/Applets/TCP/tc p.html darmstadt.de/projects/iteach/itbeankit/Applets/TCP/tc p.html Simple TCP/IP Lab  sttcpip.html?printversion sttcpip.html?printversion