Hands-On Microsoft Windows Server 2003

Networking

Chapter Three

TCP/IP Architecture

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Objectives

• Describe the overall architecture of TCP/IP• Describe application layer protocols• Discuss transport layer protocols• Understand the role of various network layer

protocols including IP, ICMP, and ARP• Understand network interface layer protocols• Describe different physical layer protocols• Discuss changes to IP introduced with IPv6

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TCP/IP Model• Application layer

– Provides access to network resources– Defines rules, commands, and procedures

• Transport layer– Breaks large messages into smaller packets of

information– Tracks whether packets arrived at final

destination• Internet layer

– Responsible for logical addressing• Networking interface layer

– Consists of network card driver and circuitry on network card itself

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TCP/IP Architecture

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Hypertext Transfer Protocol (HTTP)• The most common protocol used on the Internet

today• Defines the commands that Web browsers can

send and how Web servers are capable of responding

• Common mechanisms for passing data from a Web server to an application– Common Gateway Interface (CGI)– Internet Server Application Programmer Interface

(ISAPI)– Netscape Server Application Programmer

Interface (NSAPI)

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File Transfer Protocol (FTP)

• A simple file-sharing protocol• Includes commands for uploading and

downloading files • Implemented in stand-alone FTP clients as well

as in Web browsers

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Telnet

• A terminal emulation protocol used to remotely connect to Unix and Linux Systems

• Does not support a graphical user interface (GUI), only text

• Telnet client only responsible for displaying information on the screen and passing input to the server

• Can have many telnet clients connected to a single server at one time

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Simple Mail Transfer Protocol (SMTP)

• Used to send and receive e-mail messages between e-mail servers

• Used by e-mail client software, such as Outlook Express, to send messages to the server

• Is never used to retrieve e-mail that is being read

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Post Office Protocol version 3 (POP3)

• The most common protocol used for reading e-mail messages

• Does not support sending messages• Only supports a single inbox and does not

support multiple folders for storage on the server

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Internet Message Access Protocol version 4 (IMAP4)

• Another common protocol used to read e-mail messages

• Allows for multiple folders on the server side to store messages

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Transport Layer Protocols

• Responsible for getting data ready to move across the network

• Port– Used by transport layer protocols to direct

network information to the proper service

• Transport layer protocols in the TCP/IP protocol suite– Transmission Control Protocol (TCP)

– User Datagram Protocol (UDP)

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Common Services and Ports

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Transmission Control Protocol (TCP)

• The most commonly used transport layer protocol

• Connection-oriented and reliable• Establishment of a connection is a three-packet

process between the source and destination host

• Syn bit– Indicates that the packet is a request to negotiate

a connection

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Transmission Control Protocol (TCP) (Continued)

• Ack bit– An option in a packet that indicates this packet is

a response to the first packet

• Sliding Window– Process used to track which packets have been

received by the destination host

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TCP Three-way Handshake

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User Datagram Protocol (UDP)

• Connectionless and unreliable• Has no sliding window• The appropriate transport layer protocol to use

when you are unconcerned about missing packets

• Use also when the amount of data being exchanged is very small

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Internet Layer Protocols

• Responsible for all tasks related to logical addressing

• Internet Protocol (IP)– Responsible for the logical addressing of each

packet created by the transport layer

• Routing Information Protocol (RIP) and Open Shortest Path First (OSPF) – Responsible for defining how paths are chosen

through the internetwork from one computer to another

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Internet Layer Protocols (Continued)

• Internet Control Messaging Protocol (ICMP)– Used to send IP error and control messages

between routers and hosts

– Ping utility uses ICMP packets to test connectivity between hosts

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Common ICMP Packet Types

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Internet Layer Protocols (Continued)• Internet Group Management Protocol (IGMP)

– Used for the management of multicast groups• Address Resolution Protocol (ARP)

– Used to convert logical IP addresses to physical MAC addresses

– Data packets have four addresses: • Source IP address • Destination IP address• Source MAC address • Destination MAC address

– Uses a two-packet process to find the MAC address of the destination computer

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Computer A communicates with Computer B

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ARP Request Packet

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ARP Reply Packet

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Communication Across a Router

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Network Interface Layer Protocols• Institute of Electrical and Electronics Engineers

(IEEE)– Has system of numbered committees that each

defines a different network interface layer protocol

• Ethernet– The most common network interface layer

protocol used in corporate networks today• Token Ring

– Was commonly implemented with mainframe computers

– Uses twisted pair cabling and operates at 4 Mbps or 16 Mbps

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Network Interface Layer Protocols (Continued)

• Wireless LAN – One of the fastest growing network types

– 802.11b standard defines the most common wireless standard

• Bluetooth– Short-range wireless communication system

– Has maximum distance of approximately 30 feet and maximum speed of 720 Kbps

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Institute of Electrical and Electronics Engineers (IEEE) Protocols

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Ethernet Cabling Types and Speeds

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IPv6 Changes

• Newer versions of TCP and UDP• CHECKv4.EXE

– Utility provided by Microsoft to help developers find code that must be modified to work with IPv6

• Neighbor Solicitation multicast packet – Used to find the MAC address of an IPv6 host

– Replaces ARP

• Multicast Listener Discovery (MLD) – Replaces the functionality of IGMP

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Summary

• TCP/IP model– Application layer

– Transport layer

– Internet layer

– Network interface layer

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Summary (Continued)

• Application layer protocols– HTTP: the most common protocol in use– FTP: used for transferring files across the Internet– Telnet: used to remotely connect to UNIX and

Linux systems– SMTP: used to send and receive e-mail

messages– POP3: most common protocol used for reading e-

mail messages– IMAP4: used for reading e-mail messages

Transport layer protocols– TCP: connection-oriented and reliable– UDP: connectionless and unreliable

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Summary (Continued)• Internet layer protocols

– Responsible tasks related to logical addressing – Includes IP, RIP, OSPF, ICMP, IGMP, and ARP

• Ethernet– The most common network interface layer

protocol in use• Wireless LANs

– One of the fastest growing network types• IPv6 changes

– New versions of TCP and UDP– Discontinued use of ARP– Replacement of IGMP with Multicast Listener

Discovery