Guide to Networking Essentials Fifth Edition Chapter 6 Network - PowerPoint PPT Presentation

Guide to Networking Essentials Fifth Edition Chapter 6 Network Communications and Protocols

Objectives • Explain the function of protocols in a network • Describe common protocol suites Guide to Networking Essentials, Fifth Edition 2

Protocols • Strictly speaking, protocols are the rules and procedures for communicating – For two computers to communicate, they must speak the same language and agree on the rules of communication Guide to Networking Essentials, Fifth Edition 3

The Function of Protocols • As protocols serve their functions in the OSI model, they might work at one or many layers • When a set of protocols works cooperatively, it’s called a protocol stack or protocol suite – The most common protocol stack is TCP/ IP , the Internet protocol suite – IPX/ SPX, used in older versions of Novell NetWare, is disappearing as companies upgrade to newer versions of NetWare – Levels of a protocol stack map to their functions in the OSI model Guide to Networking Essentials, Fifth Edition 4

Connectionless Versus Connection- Oriented Protocols • Protocols that use connectionless delivery place data on the network and assume it will get through – Connectionless protocols aren’t entirely reliable – Are fast: little overhead, don’t waste time establishing/ managing/ tearing down connections • Connection- oriented protocols are more reliable and, consequently, slower – Two computers establish a connection before data transfer begins • In a connection, data is sent in an orderly fashion – Ensures that all data is received and is accurate, or that suitable error messages are generated Guide to Networking Essentials, Fifth Edition 5

Routable Versus Nonroutable Protocols • The network layer (OSI) is responsible for moving data across multiple networks – Routers are responsible for routing process • Protocol suites that function at Network layer are routable or routed protocols; otherwise, they are called nonroutable – TCP/ IP and IPX/ SPX are routable protocols – An older and nearly obsolete protocol, NetBEUI, is a nonroutable protocol that works well in small networks, but its performance drops considerably as a network grows Guide to Networking Essentials, Fifth Edition 6

Protocols in a Layered Architecture Guide to Networking Essentials, Fifth Edition 7

Protocols in a Layered Architecture (continued) • Some authors consider session- layer protocols to belong in the Transport layer Guide to Networking Essentials, Fifth Edition 8

Network Protocols • Some popular network protocols include: – Internet Protocol version 4 (IPv4 or simply IP) • Provides addressing and routing information – Internetwork Packet Exchange (IPX) • Novell’s protocol for packet routing and forwarding • Belongs to the IPX/ SPX protocol suite • Serves many of the same functions as TCP/ IP’s IP – Internet Protocol version 6 (IPv6) • A new version of IP that’s being implemented on many current networking devices and operating systems – Addresses some weaknesses of IPv4 Guide to Networking Essentials, Fifth Edition 9

Transport Protocols • Transport protocols can be connection- oriented (reliable) or connectionless (best- effort) delivery – Transmission Control Protocol (TCP) • Responsible for reliable data delivery in TCP/ IP – Sequential Packet Exchange (SPX) • Novell’s connection- oriented protocol used to guarantee data delivery – NetBIOS/NetBEUI • NetBIOS establishes/ manages communications between computers and provides naming services • NetBEUI provides data transport services for these communications Guide to Networking Essentials, Fifth Edition 10

Application Protocols • Application protocols provide services to client applications – Simple Mail Transport Protocol (SMTP) in TCP/IP – File Transfer Protocol (FTP) in TCP/IP – Simple Network Management Protocol (SNMP) • Manages and monitors network devices (TCP/ IP) – NetWare Core Protocol (NCP) • Novell’s client shells and redirectors – AppleTalk File Protocol (AFP) • Apple’s remote file- management protocol Guide to Networking Essentials, Fifth Edition 11

Common Protocol Suites • Because most protocols contain a combination of components, these components are usually bundled as a protocol suite – TCP/ IP • Dominates the networking arena to the point of making most of the other suites nearly obsolete – IPX/ SPX – NetBIOS/ NetBEUI – AppleTalk Guide to Networking Essentials, Fifth Edition 12

Transmission Control Protocol/ Internet Protocol (TCP/ IP) Guide to Networking Essentials, Fifth Edition 13

TCP/ IP Network Layer Protocols • Internet Protocol version 4 (IPv4) is a Network layer protocol that provides source and destination addressing and routing for the TCP/ IP suite – Connectionless protocol; fast but unreliable • Internet Control Message Protocol (ICMP) is a Network layer protocol used to send error and control messages between systems or devices – The Ping utility uses ICMP to request a response from a remote host to verify availability • Address Resolution Protocol (ARP) resolves logical (IP) addresses to physical (MAC) addresses Guide to Networking Essentials, Fifth Edition 14

IP, ICMP, and ARP in Action Guide to Networking Essentials, Fifth Edition 15

IP, ICMP, and ARP in Action (continued) Guide to Networking Essentials, Fifth Edition 16

TCP/ IP: Transport Layer Protocols • Transmission Control Protocol (TCP) is the primary Internet transport protocol – Connection oriented using a three- way handshake – Message fragmentation and reassembly • "Byte- oriented" means that messages are reassembled in correct order – Uses acknowledgements to ensure that all data was received and to provide flow control Guide to Networking Essentials, Fifth Edition 17

TCP/ IP: Transport Layer Protocols • User Datagram Protocol (UDP) is connectionless – Generally faster, although less reliable, than TCP • Doesn’t segment data or resequence packets • Doesn’t use acknowledgements for reliability • Used by NFS and DNS • Stream Control Transmission Protocol (SCTP) is a newer protocol – More flexibility than TCP – "Transaction" (stream) oriented – Originally intended for telephony over IP Guide to Networking Essentials, Fifth Edition 18

TCP/ IP Application Layer Protocols • Domain Name System (DNS) – Session layer name- to- address resolution protocol • Hypertext Transport Protocol (HTTP) – To transfer Web pages from Web server to browser • File Transfer Protocol (FTP) – For file transfer and directory and file manipulation • Telnet – Remote terminal emulation; operates at layers 7- 5 • Simple Mail Transport Protocol (SMTP) – Operates at layers 7- 5; provides messaging services Guide to Networking Essentials, Fifth Edition 19

IP Addressing • Logical addresses are 32 bits (4 bytes) long – Each byte is represented as an octet (decimal number from 0 to 255) – Usually represented in dotted decimal notation • E.g., 172.24.208.192 – Address has two parts: network and host ID • E.g. 172.24.208.192 (172.24.0.0 and 208.192) – Categorized into ranges referred to as classes • Class system provides basis for determining which part of address is the network and which is the host ID • The first octet of an address denotes its class Guide to Networking Essentials, Fifth Edition 20

IP Addressing (continued) • Classes – Class A: first octet between 1- 126 • 16,777,214 hosts per network address – Class B: first octet between 128- 191 • 65,534 hosts per network address – Class C: first octet between 192- 223 • 254 hosts per network address – Class D: first octet between 224- 239 • Reserved for multicasting – Class E: first octet between 240- 255 • Reserved for experimental use Guide to Networking Essentials, Fifth Edition 21

IP Addressing (continued) • 127.0.0.0 network is called the loopback address – localhost always corresponds to address 127.0.0.1 • IETF reserved addresses for private networks – Class A addresses beginning with 10 – Class B addresses from 172.16 to 172.31 – Class C addresses from 192.168.0 to 192.168.255 – These addresses can’t be routed across the Internet – To access the Internet, NAT is needed – IPv6 eliminates need for private addressing; provides a 128- bit address (vs. IPv4’s 32 bits) Guide to Networking Essentials, Fifth Edition 22