chapter 1: introducing tcp/ip2profs.net/steve/cisntwk413/ppts/ch01.pdf · • understand tcp/ip’s...

Guide to TCP/IP, Third Edition

Chapter 1:pIntroducing TCP/IP

1

CISNTWK-11PermissionsObjectives

• Understand TCP/IP’s origins and histor• Understand TCP/IP’s origins and history

• Explain the process by which TCP/IP standards and other d ll d R f C (RFC )documents, called Requests for Comments (RFCs), are created, debated, and formalized (where appropriate)

• Understand the Open Systems Interconnection network reference model, often used to characterize network protocols and services, and how it relates to TCP/IP’s own internal networking modelinternal networking model

2Introducing TCP/IP 2

CISNTWK-11PermissionsObjectives

• Define the terms involved and explain how TCP/IP protocols sockets and ports are identifiedprotocols, sockets, and ports are identified

• Understand data encapsulation and how it relates to theUnderstand data encapsulation and how it relates to the four layers of the TCP/IP protocol stack

• Understand and apply the basic practices and principles that underlie network protocol analysis


CISNTWK-11PermissionsWhat is TCP/IP?

• Large collection of networking protocols and servicesT k l• Two key protocols– Transmission Control Protocol (TCP)

• Reliable delivery of messages– Internet Protocol (IP)

• Manages the routing of network transmissions


CISNTWK-11PermissionsThe Origins and History of TCP/IP

• 1969– Advanced Research Projects Agency (ARPA) funded research for– Advanced Research Projects Agency (ARPA) funded research for

packet-switched networking– ARPANET

• Network built as a result of this project• Network built as a result of this project

• In a packet-switched network– Sender and receiver are identified by unique network addresses


CISNTWK-11PermissionsTCP/IP’s Design Goals

• To withstand a potential nuclear strikeT i diff i• To permit different computer systems to communicate easily

• To interconnect systems across long distancesTo interconnect systems across long distances


CISNTWK-11PermissionsA TCP/IP Chronology

• 1978– Internet Protocol version 4 (IPv4)– Internet Protocol version 4 (IPv4)

• 1983– Defense Communications Agency took over operation of

ARPANETARPANET• 1986

– NSF launches high-speed network (NSFNET)• 1987

– Number of hosts on the Internet breaks 10,000


CISNTWK-11PermissionsA TCP/IP Chronology (continued)

• 1989– Number of hosts on the Internet breaks 100 000– Number of hosts on the Internet breaks 100,000

• 1990– Worldwide Web is born at Centre European Researche Nucleaire

(CERN)(CERN)• 1991

– Commercial Internet Exchange (CIX) is formed• 1992

– Internet Society (ISOC) is chartered


CISNTWK-11PermissionsA TCP/IP Chronology (continued)A TCP/IP Chronology (continued)

• 1993I t NIC i h t d– InterNIC is chartered

• 1994– Online junk mail begins to proliferatej g p

• 1995– Netscape launches Netscape Navigator

• 1996– Microsoft launches Internet Explorer Web browser

• 19971997– 31 million registered domain names


CISNTWK-11PermissionsA TCP/IP Chronology (continued)

• 2000L L tt i f t illi PC– Love Letter worm infects over one million PCs

• 2001– Number of hosts on the Internet breaks 150 million– Sircam virus and Code Red worm infect thousands

• 2002204 illi I t t h t– 204 million Internet hosts

• 2003– Public Interest Registry becomes .org registry operatorg y g g y p


CISNTWK-11PermissionsWho “Owns” TCP/IP?

• TCP/IP F ll l i t th bli d i– Falls squarely into the public domain

– Funded with public monies since its inception– Owned by everybody and nobody


CISNTWK-11PermissionsMeet the Standards Groups that Manage TCP/IPMeet the Standards Groups that Manage TCP/IP

i ( )• Internet Society (ISOC)• Internet Architecture Board (IAB)• Internet Engineering Task Force (IETF)• Internet Engineering Task Force (IETF)• Internet Research Task Force (IRTF)• Internet Societal Discussion Forum (ISDF)Internet Societal Discussion Forum (ISDF)• Internet Corporation for Assigned Names and Numbers

(ICANN)


CISNTWK-11PermissionsTCP/IP Standards and RFCs

• Request For Comments (RFCs)– Provide documentation to understand implement and use TCP/IP– Provide documentation to understand, implement and use TCP/IP

protocols• Index for all RFCs available at

www faqs org/rfcs/– www.faqs.org/rfcs/ • RFC 2026

– Describes how a RFC is created


CISNTWK-11PermissionsOSI Reference Model Overview

• OSI reference modelA t k f d l– A network reference model

– Formally known as ISO/OSI – Designed to replace TCP/IP– Standard way to explain how networks operate– TCP/IP is the open standard protocol suite of choice


CISNTWK-11Permissions

Models Break Networking into LayersLayers

• Divide and conquer approachS t t ki h d f th l t d t– Separates networking hardware concerns from those related to networking software

• Key points about networking– Easier to solve problems when broken into series of smaller

problems– Layers operate independently of one anothery p p y– Changes to one layer need not affect other layers



Models Break Networking into Layers (continued)Layers (continued)

• Key points about networkingI di id l l k t th i f t– Individual layers work together on pairs of computers

– Different expertise is needed at each layer– Network protocols usually map into one or more layers– TCP/IP is designed around a layered model


CISNTWK-11PermissionsHow Protocol Layers Behave

• Layers– Exist to encapsulate or isolate specific types of functionality– Exist to encapsulate or isolate specific types of functionality– Provide services to the layer above– Deliver data to or accept data from the layer below

P t l D t U it (PDU )• Protocol Data Units (PDUs) – Include “envelope information” in the form of specific headers and

trailers


CISNTWK-11PermissionsPhysical Layer

• Includes the physical transmission medium • Job is to activate maintain and deactivate network• Job is to activate, maintain, and deactivate network

connections • Manages communications with the network medium going

d h l kdown the protocol stack • Handles conversion of outgoing data


CISNTWK-11PermissionsData Link Layer

• Situated between the Physical layer and the Network layer in the reference modelin the reference model

• Job is to – Enable reliable transmission of data through the Physical layer at g y y

the sending end – Check reliability at the receiving end

• Manages point-to-point transmission across the networking• Manages point-to-point transmission across the networking medium


CISNTWK-11PermissionsNetwork Layer

• Handles logical addresses associated with individual machines on a networkmachines on a network

• Uses addressing information to – Determine how to send a PDU

• Embodies notion of multiple simultaneous connections between different IP addresses

l ibl h• Flexible enough to – Recognize and use multiple routes between a sender and a receiver


CISNTWK-11PermissionsTransport Layer

• Ensures reliable end-to-end transmission of PDUs• Includes end to end error detection and error recovery• Includes end-to-end error-detection and error-recovery• Segmentation

– Involves cutting up a big message into a numbered sequence of g p g g qchunks, called segments

• PDUs used at the Transport layer are called segments, or data segmentsdata segments


CISNTWK-11PermissionsSession Layer

• Defines mechanisms to P it d d i t t th t ti t t– Permit senders and receivers to request that a conversation start or stop

– Keep a conversation going even when traffic may not otherwise fl b t th ti i l dflow between the parties involved

• Checkpoints– Define the last point up to which successful communications are p p

known to have occurred


CISNTWK-11PermissionsPresentation Layer

• Handles transforming data from G i t k i t d f f i t ifi– Generic, network-oriented forms of expression to more specific, platform-oriented forms of expression

• A redirector or network shell– Special computer facility that resides here

• Can supply special data-handling functions for applications


CISNTWK-11PermissionsApplication Layer

• Defines an interface that applications can use to request network servicesnetwork services

• Defines a set of access controls over the network• PDUsPDUs

– Generically called Application PDUs


CISNTWK-11PermissionsThe TCP/IP Networking Model

• Design model that describes TCP/IP differs somewhat from OSI reference modelfrom OSI reference model

• Transport layers for both models map together quite well as does the– Network layer from the OSI reference model and the Internet layer

from the TCP/IP model


CISNTWK-11PermissionsTCP/IP Network Access Layer

• Includes Ethernet, token ring, and wireless media devicesI l d WAN d i l• Includes WAN and connection-management protocols

• The IEEE standards for networking apply– Including the IEEE 802 family of standardsIncluding the IEEE 802 family of standards



TCP/IP Network Access Layer ProtocolsProtocols

• PPP– Most important TCP/IP Network Access layer protocol

PPP E (“PPP E h ” )• PPPoE (“PPP over Ethernet” )– Widely used on Ethernet networks or those with Ethernet-like

characteristics

• SLIP– Older, simpler serial line protocol that only supports TCP/IP-based

communicationscommunications


CISNTWK-11PermissionsTCP/IP Internet Layer Functions

• Handle routing between machines across multiple networksnetworks

• Three primary tasks– MTU fragmentationg– Addressing– Routing


CISNTWK-11PermissionsTCP/IP Internet Layer Protocols

• Internet Protocol (IP)I C l M P l (ICMP)• Internet Control Message Protocol (ICMP)

• Packet Internetwork Groper (PING)• Address Resolution Protocol (ARP)• Address Resolution Protocol (ARP)• Reverse ARP (RARP)• Bootstrap Protocol (BOOTP)p ( )• Routing Information Protocol (RIP)


CISNTWK-11PermissionsTCP/IP Transport Layer Functions

• FunctionsR li bl d li f d t f d t i– Reliable delivery of data from sender to receiver

– Fragmentation of outgoing messages and their reassembly prior to delivery to the Application layer

• Hosts– Devices that operate on the Internet


CISNTWK-11PermissionsTCP/IP Transport Layer Protocols

• Two TCP/IP Transport layer protocols Th t i i C t l P t l (TCP)– The transmission Control Protocol (TCP)

• Connection-oriented– The User Datagram Protocol (UDP)

• Connectionless

• UDP– Transmits data in a “best-effort delivery”Transmits data in a best effort delivery – Does no follow-up checking on its receipt


CISNTWK-11PermissionsTCP/IP Application Layer

• Also known as the Process layerTCP/IP i d d• TCP/IP services depend on:– Special “listener process,” called a daemon

• Operates on a server to handle incoming user requests for specific services

– Each TCP/IP service has an associated port address



TCP/IP Protocols, Services, Sockets, And Ports

l i l i• Multiplexing– Combining various sources of outgoing data into a single output data

stream

• Demultiplexing– Breaking up an incoming data stream so separate portions may be

delivered to the correct applicationsdelivered to the correct applications

• Well-known protocols– Assign a series of numbers to represent a sizable collection of

/ b d k iTCP/IP-based network services


CISNTWK-11PermissionsTCP/IP Port Numbers

• TCP/IP application processes S ti ll d t k i– Sometimes called network services

– Identified by port numbers

• Source port numberp– Identifies the process that sent the data

• Destination port number Id tifi th t i th t d t– Identifies the process to receive that data


CISNTWK-11PermissionsTCP/IP Sockets

• Well-known or registered portsR t i d t b– Represent pre-assigned port numbers

• Socket address (or socket)– The combination of a particular IP address and a dynamically p y y

assigned port address


CISNTWK-11PermissionsData Encapsulation In TCP/IP

• At each layer in the TCP/IP protocol stackO t i d t i k d d id tifi d f d li t th l– Outgoing data is packaged and identified for delivery to the layer underneath

• Header– PDU’s own particular opening component – Identifies the protocol in use, the sender and intended recipient

• Trailer (or packet trailer)• Trailer (or packet trailer)– Provides data integrity checks for the payload


CISNTWK-11PermissionsAbout Protocol Analysis

• Protocol analysis is the process of– Tapping into the network communications system– Tapping into the network communications system– Capturing packets– Gathering network statistics

Decoding packets– Decoding packets• Popular Windows-based protocol analyzers

– Ethereal for Windows (Gerald Combs)– Sniffer Network Analyzer (Network Associates)


CISNTWK-11PermissionsUseful Roles for Protocol Analysis

• Used to troubleshoot network communications• Used to test networks• Used to test networks

– Passive– Active

• Gather trends on network performance• Analyzers available for variety of platforms


CISNTWK-11PermissionsProtocol Analyzer Elements

• Promiscuous mode card and driverP k fil• Packet filters

• Trace buffer• Decodes• Decodes• Alarms• Statistics



Placing a Protocol Analyzer on a NetworkNetwork

• Protocol analyzerC t k t th t it th t k– Captures packets that it can see on the network

• On network connected with hubs– You can place analyzer anywhere on the networkp y y

• Options for analyzing switched networks– Hubbing out

P t di ti– Port redirection– Remote Monitoring (RMON)


CISNTWK-11PermissionsSummary

• TCP/IP design goals– To support multiple packet-switched pathways through the– To support multiple, packet-switched pathways through the

network – To permit dissimilar computer systems to easily exchange data– To offer robust reliable delivery services for both short- and long-To offer robust, reliable delivery services for both short and long

haul communications– To provide comprehensive network access with global scope


CISNTWK-11PermissionsSummary (continued)

• Initial implementations of TCP/IP F d d b Ad d R h P j t A– Funded by Advanced Research Projects Agency

• TCP/IP remains in the public domain• As Standard RFCs go through approval process they beginAs Standard RFCs go through approval process they begin

as Proposed Standard documents• Best Current Practice (BCP)

– An informational (non-standard) RFC


CISNTWK-11PermissionsSummary (continued)

• ISO/OSI network reference modelB k t ki i t di ti t l– Breaks networking into seven distinct layers

• TCP/IP uses a variety of encapsulation techniques at its various layers to y– Label the type of data contained in the contents, or payloads, of its

PDUs

• Protocol analysis• Protocol analysis – Network interface inspects all traffic moving across a segment of

network medium


chapter 1: introducing tcp/ip2profs.net/steve/cisntwk413/ppts/ch01.pdf · • understand tcp/ip’s...

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