Chapter Three Network Protocols

Introduction to Protocols Rules network uses to transfer data Protocols that can span more than one LAN segment are routable SNA & DLC becoming outdated due to non-routability Multiprotocol network Network using more than one protocol

TCP/IP Transmission Control Protocol/Internet Protocol (TCP/IP) OSI Model TCP/IP Transmission Control Protocol/Internet Protocol (TCP/IP) Suite of small, specialized protocols called subprotocols Figure 3-1: TCP/IP compared to the OSI Model

The TCP/IP Core Protocols Certain subprotocols of TCP/IP suite Operate in Transport or Network layers of OSI Model Provide basic services to protocols in other layers of TCP/IP TCP and IP are most significant core protocols in TCP/IP suite

Internet Protocol (IP) Provides information about how and where data should be delivered Subprotocol that enables TCP/IP to internetwork To internetwork is to traverse more than one LAN segment and more than one type of network through a router In an internetwork, the individual networks that are joined together are called subnetworks (or subnets)

Internet Protocol (IP) IP datagram IP portion of TCP/IP frame that acts as an envelope for data Contains information necessary for routers to transfer data between subnets Figure 3-2: Components of an IP datagram

Internet Protocol (IP) Version IPv4 – current version used for 20 years IPv6 – in process Time to live (TTL) – max time, in seconds, that a datagram can remain on the network before it is discarded Also corresponds to # of router hops

Internet Protocol (IP) IP is an unreliable, connectionless protocol, which means it does not guarantee delivery of data Connectionless Allows protocol to service a request without requesting verified session and without guaranteeing delivery of data

Transport Control Protocol (TCP) Provides reliable data delivery services Connection-oriented subprotocol Requires establishment of connection between communicating nodes before protocol will transmit data TCP segment Holds TCP data fields Becomes encapsulated by IP datagram

Transport Control Protocol (TCP) Address on host where application makes itself available to incoming data Figure 3-3: A TCP segment

Additional Core Protocols of the TCP/IP Suite User Datagram Protocol (UDP) Connectionless transport service Lack of sophistication makes it more efficient than TCP Live audio/video transmissions over the Internet Internet Control Message Protocol (ICMP) Notifies sender of an error in transmission process and that packets were not delivered Sits between IP & TCP in Internet layer of TCP/IP model Used by PING diagnostic tool Address Resolution Protocol (ARP) Obtains MAC address of host or node Creates local database mapping MAC address to host’s IP address

TCP/IP Application Layer Protocols These protocols work over TCP (or UDP) and IP: Telnet Used to log on to remote hosts using TCP/IP protocol suite File Transfer Protocol (FTP) Used to send and receive files via TCP/IP Simple Mail Transfer Protocol (SMTP) Responsible for moving messages from one e-mail server to another, using the Internet and other TCP/IP-based networks Simple Network Management Protocol (SNMP) Manages devices on a TCP/IP network

Addressing in TCP/IP IP Address Logical address used in TCP/IP networking Unique 32-bit number Divided into four groups of octets (8-bit bytes) that are separated by periods IP addresses are assigned and used according to very specific parameters Example: 144.92.43.178

Addressing in TCP/IP Table 3-1: Commonly used TCP/IP classes Though 8 bits have 256 possible combinations, only the numbers 1 through 254 are used to identify networks and hosts Numbers 0 and 255 are reserved for broadcasts Broadcast are transmissions to all stations on a network

Addressing in TCP/IP Group A Group B Group C Only 126 available – used/reserved for large corporations or governments Share the first octet (1-126) i.e. 23.78.110.109, 23.164.32.97 Group B Share the first two octets (128-191) i.e. 168.34.88.29, 168.34.55.41 Group C Share the first three octets (192-223) i.e 204.139.118.7, 204.139.118.14

Addressing in TCP/IP Loopback address IP address reserved for communicating from a node to itself Value of the loopback address is always 127.0.0.1 (try it) Internet Corporation for Assigned Names and Numbers (ICANN) – formerly InterNIC Non-profit organization currently designated by U.S. government to maintain and assign IP addresses

Addressing in TCP/IP Firewall Host Specialized device (typically a router) Selectively filters or blocks traffic between networks May be strictly hardware-based or may involve a combination of hardware and software Host Computer connected to a network using the TCP/IP protocol

Addressing in TCP/IP IP address data are sent across the network in binary form In IP address 131.127.3.22, to convert the first octet (131) to a binary number: On Windows 2000, click Start, point to Programs, point to Accessories, then click Calculator Click View, then click Scientific (make sure Dec option button is selected) Type 131, then click Bin option button The binary equivalent of number 131, 10000011, appears in the display window

Addressing in TCP/IP Static IP address IP address manually assigned to a device Dynamic Host Configuration Protocol (DHCP) Application layer protocol Manages dynamic distribution of IP addresses on a network

Viewing Current IP Information Figure 3-4: Example of an IP configuration window

Viewing Current IP Information Figure 3-5: IP address information on a Windows 2000 workstation

Addresses and Names In addition to using IP addresses, TCP/IP networks use names for networks and hosts Each host requires a host name Each network requires a network name, also called a domain name Together, host name and domain name constitute the fully qualified domain name (FQDN)

Figure 3-6: IPX/SPX compared to the OSI Model Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) Protocol originally developed by Xerox Modified and adopted by Novell in the 1980s for the NetWare network operating system Figure 3-6: IPX/SPX compared to the OSI Model

IPX/SPX Core Protocols Internetwork Packet Exchange (IPX) Operates at Network layer of OSI Model Provides routing and internetworking services Similar to IP in TCP/IP suite Socket – logical address assigned to a specific process Figure 3-7: Components of an IPX datagram

IPX/SPX Core Protocols Sequenced Packet Exchange (SPX) Belongs to Transport layer of OSI Model Works in tandem with IPX to ensure data are received: Whole In sequence Error free Similar to TCP

IPX/SPX Core Protocols Figure 3-8: SPX packet encapsulated by an IPX datagram

IPX/SPX Core Protocols Service Advertising Protocol (SAP) Works in Application, Presentation, Session, and Transport layers of OSI Model Runs directly over IPX Used by NetWare servers and routers to advertise to entire network which services they can provide Can lead to unnecessary network traffic

IPX/SPX Core Protocols NetWare Core Protocol (NCP) Works within Presentation and Sessions layers of OSI Model Works over IPX Handles requests for services between clients and servers

Addressing in IPX/SPX IPX address Address assigned to a device on an IPX/SPX network Contains two parts: Network address (external network number) Established Network Admin when network is installed Node address NIC MAC address Example (8.12): 000008A2:0060973E97F3

NetBIOS and NetBEUI Network Basic Input Output System (NetBIOS) Originally designed by IBM to provide Transport and Session layer services Adopted by Microsoft as its foundation protocol Microsoft added Application layer component called NetBEUI

NetBIOS and NetBEUI NetBIOS Enhanced User Interface Fast and efficient protocol Consumes few network resources Provides excellent error correction Requires little configuration Can handle only 254 connections Does not allow for good security By itself, it is not routable

NetBIOS and NetBEUI Compared to the OSI Model Figure 3-9: NetBIOS/NetBEUI compared to the OSI Model

Figure 3-10: Identification tab in Network properties NetBIOS Addressing Figure 3-10: Identification tab in Network properties

AppleTalk Apple has begun supporting TCP/IP Protocol suite used to interconnect Macintosh computers Originally designed to support peer-to-peer networking among Macintoshes Can now be routed between network segments and integrated with NetWare- and Microsoft-based networks AppleTalk networks are separated into logical groups of computers called AppleTalk zones Apple has begun supporting TCP/IP

AppleTalk and OSI Model Figure 3-11: AppleTalk protocol compared to OSI Model

Addressing in AppleTalk AppleTalk node ID Unique 8-bit or 16-bit number identifying a computer on an AppleTalk network AppleTalk network number Unique 16-bit number identifying the network to which a node is connected

Installing Protocols After installing protocols, they must be binded to NICs and services they run on or with Binding Process of assigning one network component to work with another