Chapter 1: Introducing TCP/IP
Understand TCP/IP s origins and history Explain the process by which TCP/IP standards and other 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 model Introducing TCP/IP 2
Define the terms involved and explain how TCP/IP protocols, sockets, and ports are identified Understand 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 Introducing TCP/IP 3
Large collection of networking protocols and services Two key protocols o Transmission Control Protocol (TCP) Reliable delivery of messages o Internet Protocol (IP) Manages the routing of network transmissions Introducing TCP/IP 4
1969 o Advanced Research Projects Agency (ARPA) funded research for packet-switched networking o ARPANET Network built as a result of this project In a packet-switched network o Sender and receiver are identified by unique network addresses Introducing TCP/IP 5
To withstand a potential nuclear strike To permit different computer systems to communicate easily To interconnect systems across long distances Introducing TCP/IP 6
1978 o Internet Protocol version 4 (IPv4) 1983 o Defense Communications Agency took over operation of ARPANET 1986 o NSF (National Science Foundation) launches high-speed network (NSFNET) 1987 o Number of hosts on the Internet breaks 10,000 Introducing TCP/IP 7
1989 o Number of hosts on the Internet breaks 100,000 1990 o Worldwide Web is born at Centre European Researche Nucleaire (CERN) 1991 o Commercial Internet Exchange (CIX) is formed 1992 o Internet Society (ISOC) is chartered Introducing TCP/IP 8
1993 o InterNIC (Network Information Center) is chartered 1994 o Online junk mail begins to proliferate 1995 o Netscape launches Netscape Navigator 1996 o Microsoft launches Internet Explorer Web browser 1997 o 31 million registered domain names Introducing TCP/IP 9
2000 o Love Letter worm infects over one million PCs 2001 o Number of hosts on the Internet breaks 150 million o Sircam virus and Code Red worm infect thousands 2002 o 204 million Internet hosts 2003 o Public Interest Registry becomes.org registry operator Introducing TCP/IP 10
TCP/IP o Falls squarely into the public domain o Funded with public monies since its inception o Owned by everybody and nobody Introducing TCP/IP 11
Internet Society (ISOC) Internet Architecture Board (IAB) Internet Engineering Task Force (IETF) Internet Research Task Force (IRTF) Internet Societal Discussion Forum (ISDF) Internet Corporation for Assigned Names and Numbers (ICANN) Introducing TCP/IP 12
Request For Comments (RFCs) o Provide documentation to understand, implement and use TCP/IP protocols Index for all RFCs available at o www.faqs.org/rfcs/ RFC 2026 o Describes how a RFC is created Introducing TCP/IP 13
OSI reference model o A network reference model o Formally known as ISO/OSI o Designed to replace TCP/IP o Standard way to explain how networks operate o TCP/IP is the open standard protocol suite of choice Introducing TCP/IP 14
Divide and conquer approach o Separates networking hardware concerns from those related to networking software Key points about networking o Easier to solve problems when broken into series of smaller problems o Layers operate independently of one another o Changes to one layer need not affect other layers Introducing TCP/IP 15
Key points about networking o Individual layers work together on pairs of computers o Different expertise is needed at each layer o Network protocols usually map into one or more layers o TCP/IP is designed around a layered model Introducing TCP/IP 16
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Layers o Exist to encapsulate or isolate specific types of functionality o Provide services to the layer above o Deliver data to or accept data from the layer below Protocol Data Units (PDUs) o Include envelope information in the form of specific headers and trailers Introducing TCP/IP 18
Includes the physical transmission medium Job is to activate, maintain, and deactivate network connections Manages communications with the network medium going down the protocol stack Handles conversion of outgoing data Introducing TCP/IP 19
Situated between the Physical layer and the Network layer in the reference model Job is to o Enable reliable transmission of data through the Physical layer at the sending end o Check reliability at the receiving end Manages point-to-point transmission across the networking medium Introducing TCP/IP 20
Handles logical addresses associated with individual machines on a network Uses addressing information to o Determine how to send a PDU Embodies notion of multiple simultaneous connections between different IP addresses Flexible enough to o Recognize and use multiple routes between a sender and a receiver Introducing TCP/IP 21
Ensures reliable end-to-end transmission of PDUs Includes end-to-end error-detection and error-recovery Segmentation o Involves cutting up a big message into a numbered sequence of chunks, called segments PDUs used at the Transport layer are called segments, or data segments Introducing TCP/IP 22
Defines mechanisms to o Permit senders and receivers to request that a conversation start or stop o Keep a conversation going even when traffic may not otherwise flow between the parties involved Checkpoints o Define the last point up to which successful communications are known to have occurred Introducing TCP/IP 23
Handles transforming data from o Generic, network-oriented forms of expression to more specific, platform-oriented forms of expression A redirector or network shell o Special computer facility that resides here Can supply special data-handling functions for applications Introducing TCP/IP 24
Defines an interface that applications can use to request network services Defines a set of access controls over the network PDUs o Generically called Application PDUs Introducing TCP/IP 25
Design model that describes TCP/IP differs somewhat from OSI reference model Transport layers for both models map together quite well as does the o Network layer from the OSI reference model and the Internet layer from the TCP/IP model Introducing TCP/IP 26
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Includes Ethernet, token ring, and wireless media devices Includes WAN and connection-management protocols The IEEE standards for networking apply o Including the IEEE 802 family of standards Introducing TCP/IP 28
PPP o Most important TCP/IP Network Access layer protocol PPPoE ( PPP over Ethernet ) SLIP o Widely used on Ethernet networks or those with Ethernet-like characteristics o Older, simpler serial line protocol that only supports TCP/IPbased communications Introducing TCP/IP 29
Handle routing between machines across multiple networks Three primary tasks o MTU fragmentation o Addressing o Routing Introducing TCP/IP 30
Internet Protocol (IP) Internet Control Message Protocol (ICMP) Packet Internetwork Groper (PING) Address Resolution Protocol (ARP) Reverse ARP (RARP) Bootstrap Protocol (BOOTP) Routing Information Protocol (RIP) Introducing TCP/IP 31
Functions o Reliable delivery of data from sender to receiver o Fragmentation of outgoing messages and their reassembly prior to delivery to the Application layer Hosts o Devices that operate on the Internet Introducing TCP/IP 32
Two TCP/IP Transport layer protocols o The transmission Control Protocol (TCP) Connection-oriented o The User Datagram Protocol (UDP) Connectionless UDP o Transmits data in a best-effort delivery o Does no follow-up checking on its receipt Introducing TCP/IP 33
Also known as the Process layer TCP/IP services depend on: o Special listener process, called a daemon Operates on a server to handle incoming user requests for specific services o Each TCP/IP service has an associated port address Introducing TCP/IP 34
Multiplexing o Combining various sources of outgoing data into a single output data stream Demultiplexing o Breaking up an incoming data stream so separate portions may be delivered to the correct applications Well-known protocols o Assign a series of numbers to represent a sizable collection of TCP/IP-based network services Introducing TCP/IP 35
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TCP/IP application processes o Sometimes called network services o Identified by port numbers Source port number o Identifies the process that sent the data Destination port number o Identifies the process to receive that data Introducing TCP/IP 37
Well-known or registered ports o Represent pre-assigned port numbers Socket address (or socket) o The combination of a particular IP address and a dynamically assigned port address Introducing TCP/IP 38
At each layer in the TCP/IP protocol stack o Outgoing data is packaged and identified for delivery to the layer underneath Header o PDU s own particular opening component o Identifies the protocol in use, the sender and intended recipient Trailer (or packet trailer) o Provides data integrity checks for the payload Introducing TCP/IP 39
Protocol analysis is the process of o Tapping into the network communications system o Capturing packets o Gathering network statistics o Decoding packets Popular Windows-based protocol analyzers o Ethereal for Windows (Gerald Combs) o Sniffer Network Analyzer (Network Associates) Introducing TCP/IP 40
Used to troubleshoot network communications Used to test networks o Passive o Active Gather trends on network performance Analyzers available for variety of platforms Introducing TCP/IP 41
Promiscuous mode card and driver Packet filters Trace buffer Decodes Alarms Statistics Introducing TCP/IP 42
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Protocol analyzer o Captures packets that it can see on the network On network connected with hubs o You can place analyzer anywhere on the network Options for analyzing switched networks o Hubbing out o Port redirection o Remote Monitoring (RMON) Introducing TCP/IP 46
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TCP/IP design goals o To support multiple, packet-switched pathways through the network o To permit dissimilar computer systems to easily exchange data o To offer robust, reliable delivery services for both short- and longhaul communications o To provide comprehensive network access with global scope Introducing TCP/IP 48
Initial implementations of TCP/IP o Funded by Advanced Research Projects Agency TCP/IP remains in the public domain As Standard RFCs go through approval process they begin as Proposed Standard documents Best Current Practice (BCP) o An informational (non-standard) RFC Introducing TCP/IP 49
ISO/OSI network reference model o Breaks networking into seven distinct layers TCP/IP uses a variety of encapsulation techniques at its various layers to o Label the type of data contained in the contents, or payloads, of its PDUs Protocol analysis o Network interface inspects all traffic moving across a segment of network medium Introducing TCP/IP 50