Network Protocols

1
Chapter 4 Network Protocols
2
Objectives

• Identify the characteristics of TCP/IP, IPX/SPX,
  NetBIOS, and AppleTalk
• Understand how key network protocols correlate to
  layers of the OSI Model
• Identify the core protocols of the TCP/IP suite
  and describe their functions

3
Objectives (continued)

• Understand the most popular protocol addressing
  schemes
• Describe the purpose and implementation of the
  domain name system
• Install protocols on Windows XP clients

4
Introduction To Protocols

• Protocol is a rule that governs how networks
  communicate
• Define the standards for communication between
  network devices
• Vary according to their speed, transmission
  efficiency, utilization of resources, ease of
  setup, compatibility, and ability to travel
  between different LANs

5
Introduction To Protocols

• Networks running more than one protocol are
  called multiprotocol networks

6
Transmission Control Protocol/Internet Protocol
(TCP/IP)

• TCP/IP is not simply one protocol, but rather a
  suite of specialized protocolsincluding TCP, IP,
  UDP, ARP, and many otherscalled sub protocols
• Extremely popular because of low cost

7
TCP/IP (continued)

• Has ability to communicate between a multitude of
  dissimilar platforms
• The core protocols are free and their code is
  available for anyone to read or modify
• Its routable, because they carry Network layer
  addressing information that can be interpreted by
  a router

8
TCP/IP (continued)

• Has flexibility because it can run on virtually
  any combination of network operating systems or
  network media
• TCP/IP Compared to the OSI Model
• The TCP/IP suite of protocols can be divided into
  four layers that roughly correspond to the seven
  layers of the OSI Model

9
TCP/IP (continued)

• TCP/IP Compared to the OSI Model (continued)
• Application layer
• Applications gain access to the network through
  this layer, via protocols
• Transport layer
• Holds the Transmission Control Protocol (TCP) and
  User Datagram Protocol (UDP), which provide flow
  control, error checking, and sequencing

10
TCP/IP (continued)

• TCP/IP Compared to the OSI Model (continued)
• Internet layer
• Holds the Internet Protocol (IP), Internet
  Control Message Protocol (ICMP), and Address
  Resolution Protocol (ARP).These protocols handle
  message routing, error reporting, delivery
  confirmation, and logical addressing
• Network Interface Layer
• This layer handles the formatting of data and
  transmission to the network wire

11
TCP/IP (continued)

• The TCP/IP Core Protocols
• Certain sub protocols of the TCP/IP suite
• Operate in the Transport or Network layers of the
  OSI Model

12
TCP/IP (continued)

• Transmission Control Protocol (TCP)
• Operates in the Transport layer of both the OSI
  and the TCP/IP Models and provides reliable data
  delivery services
• TCP is a connection-oriented sub protocol

13
TCP/IP (continued)

• Fields belonging to a TCP segment are described
  in the following list
• Source port
• Destination port
• Sequence number

14
TCP/IP (continued)

• Acknowledgment number (ACK)
• TCP header length
• Reserved
• Flags
• Sliding-window size (or window)

15
TCP/IP (continued)

• Checksum - Allows the receiving node to determine
  whether the TCP segment became corrupted during
  transmission
• Urgent pointer - Indicate a location in the data
  field
• Options - Used to specify special options

16
TCP/IP (continued)

• Padding - Contains filler information to ensure
  that the size of the TCP header is a multiple of
  32 bits
• Data - Contains data originally sent by the
  source node and the size of the Data field
  depends on how much data needs to be transmitted

17
TCP/IP (continued)

• User Datagram Protocol (UDP)
• A connectionless transport service
• UDP offers no assurance that packets will be
  received in the correct sequence

18
TCP/IP (continued)

• User Datagram Protocol (UDP)
• Provides no error checking or sequencing
• More efficient for carrying messages that fit
  within one data packet

19
TCP/IP (continued)

• Internet Protocol (IP)
• Provides information about how and where data
  should be delivered, including the datas source
  and destination addresses
• IP is the sub protocol that enables TCP/IP to
  internetwork

20
TCP/IP (continued)

• Internet Protocol (IP)
• IP datagram acts as an envelope for data and
  contains information necessary for routers to
  transfer data between different LAN segments
• IP is an unreliable, connectionless protocol,
  which means that it does not guarantee delivery
  of data

21
TCP/IP (continued)

• Internet Control Message Protocol (ICMP)
• An Internet layer protocol that reports on the
  success or failure of data delivery
• ICMP announcements provide critical information
  for troubleshooting network problems

22
TCP/IP (continued)

• Address Resolution Protocol (ARP)
• An Internet layer protocol that obtains the MAC
  (physical) address of a host, or node, then
  creates a database that maps the MAC address to
  the hosts IP (logical) address ( IP to MAC )

23
TCP/IP (continued)

• Address Resolution Protocol (ARP) table
• Dynamic ARP table entries are created when a
  client makes an ARP request that cannot be
  satisfied by data already in the ARP table
• Static ARP table entries are those that someone
  has entered manually using the ARP utility
• ARP can be a valuable troubleshooting tool

24
TCP/IP (continued)

• Reverse Address Resolution Protocol (RARP)
• Allow the client to send a broadcast message with
  its MAC address and receive an IP address in
  reply ( MAC to IP )
• RARP was originally developed as a means for
  diskless workstations

25
TCP/IP (continued)

• Addressing in TCP/IP
• Two kinds of addresses Logical or physical

26
TCP/IP (continued)

• Logical (or Network layer) can be manually or
  automatically assigned and must follow rules set
  by the protocol standards
• Physical (or MAC, or hardware) addresses are
  assigned to a devices network interface card at
  the factory by its manufacturer
• Addresses on TCP/IP-based networks are often
  called IP addresses

27
TCP/IP (continued)

• IP addresses are assigned and used according to
  very specific parameters
• Each IP address is a unique 32-bit number,
  divided into four octets, or sets of 8-bits, that
  are separated by periods
• An IP address contains two types of information
  network and host
• From the first octet you can determine the
  network class
• Three types of network classes are used on modern
  LANs Class A, Class B, and Class C

28
TCP/IP (continued)

• IP Addresses specific parameters continued
• Class D and Class E addresses do exist, but are
  rarely used
• Class D addresses are reserved for a special type
  of transmission called multicasting
• Multicasting allows one device to send data to a
  specific group of devices

29
TCP/IP (continued)

• IP Addresses specific parameters continued
• Some IP addresses are reserved for special
  functions, like broadcasts, and cannot be
  assigned to machines or devices
• 127 is not a valid first octet for any IP address
• The range of addresses beginning with 127 is
  reserved for a device communicating with itself,
  or performing loopback communication

30
TCP/IP (continued)

• The command used to view IP information on a
  Windows XP workstation is ipconfig

31
TCP/IP (continued)

• Binary and Dotted Decimal Notation
• A decimal number between 1 and 255 represents
  each binary octet (for a total of 256
  possibilities)
• The binary system is the way that computers
  interpret IP addresses
• In this system every piece of information is
  represented by 1s and 0s and each 1 or 0
  constitutes a bit

32
TCP/IP (continued)

• Subnet Mask
• A special 32-bit number that, when combined with
  a devices IP address, informs the rest of the
  network about the segment or network to which the
  device is attached
• A more common term for subnet mask is net mask,
  and sometimes simply mask
• Subnetting is a process of subdividing a single
  class of network into multiple, smaller logical
  networks, or segments

33
TCP/IP (continued)

• Assigning IP Addresses
• Every node on a network must have a unique IP
  address
• If you add a node to a network and its IP address
  is already in use by another node on the same
  subnet, an error message will be generated on the
  new client

34
TCP/IP (continued)

• A manually assigned IP address is called a static
  IP address
• Most network administrators rely on a network
  service to automatically assign them

35
TCP/IP (continued)

• Two methods of automatic IP addressing BOOTP
  and DHCP
• Bootstrap Protocol (BOOTP), an Application layer
  protocol, uses a central list of IP addresses and
  their associated devices MAC addresses to assign
  IP addresses to clients dynamically

36
TCP/IP (continued)

• An IP address that is assigned to a device upon
  request and is changeable is known as a dynamic
  IP address
• BOOTP has the potential to issue additional
  information, such as the clients subnet mask and
  requires administrators to enter every IP and MAC
  address manually into the BOOTP table

37
TCP/IP (continued)

• Dynamic Host Configuration Protocol (DHCP)
• An automated means of assigning a unique IP
  address to every device on a network
• DHCP does not require a table of IP and MAC
  addresses on the server
• DHCP does require configuration of DHCP service
  on a DHCP server

38
TCP/IP (continued)

• Terminating a DHCP Lease
• A DHCP lease may expire based on the period
  established for it in the server configuration or
  it may be manually terminated
• Sockets and Ports
• Every process on a machine is assigned a port
  number and the processs port number plus its
  host machines IP address equals the processs
  socket

39
TCP/IP (continued)

• Port numbers range from 0 to 65,539 and are
  divided by IANA into three types Well Known
  Ports, Registered Ports, and Dynamic and/or
  Private Ports
• Well Known Ports are in the range of 0 to 1023
  and are assigned to processes that only the
  operating system or an Administrator of the
  system can access
• The use of port numbers simplifies TCP/IP
  communications and ensures that data are
  transmitted to the correct application

40
TCP/IP (continued)

• Registered Ports are in the range of 1024 to
  49151. These ports are accessible to network
  users and processes that do not have special
  administrative privileges
• Dynamic and/or Private Ports are those from 49152
  through 65535 and are open for use without
  restriction

41
TCP/IP (continued)

• Addressing in IPv6
• Known as IP next generation, or Ipng is slated to
  replace the current IP protocol, IPv4
• IPv6 offers several advantages over IPv4,
  including a more efficient header, better
  security, better prioritization allowances, and
  automatic IP address configuration
• The most valuable advantage IPv6 offers is its
  promise of billions and billions of additional IP
  addresses through its new addressing scheme

42
TCP/IP (continued)

• Addressing in IPv6 (continued)
• The most notable difference between IP addresses
  in IPv4 and IPv6 is their size
• IPv4 addresses are composed of 32 bits, IPv6 are
  eight 16-bit fields and total 128 bits
• IPv4 address contains binary numbers separated by
  a period, each field in an IPv6 address contains
  hexadecimal numbers separated by a colon

43
TCP/IP (continued)

• Host Names and Domain Name System (DNS) every
  device on the Internet is technically known as a
  host and every host can take a host name

44
TCP/IP (continued)

• Domain Names every host is a member of a domain,
  or a group of computers that belong to the same
  organization and have part of their IP addresses
  in common
• A domain name is associated with a company or
  other type of organization
• Local host name plus its domain name is a fully
  qualified host name

45
TCP/IP (continued)

• A domain name is represented by a series of
  character strings, called labels, separated by
  dots
• Each label represents a level in the domain
  naming hierarchy
• In the domain name, www.novell.com, com is the
  top-level domain (TLD), novell is the
  second-level domain, and www is the third-level
  domain
• Domain names must be registered with an Internet
  naming authority that works on behalf of ICANN

46
TCP/IP (continued)

• Domain Name System (DNS)
• A hierarchical way of associating domain names
  with IP addresses
• DNS refers to both the Application-layer
  service and the organized system of computers and
  databases

47
TCP/IP (continued)

• The DNS service does not rely on one file or even
  one server, but rather on many computers across
  the globe
• These computers are related in a hierarchical
  manner, with thirteen computers, known as root
  servers, acting as the ultimate authorities

48
TCP/IP (continued)

• DNS service is divided into three components
  resolvers, name servers, and name space
• Resolvers are any hosts on the Internet that need
  to look up domain name information

49
TCP/IP (continued)

• Name servers (or DNS servers) are servers that
  contain databases of associated names and IP
  addresses and provide this information to
  resolvers on request
• The term name space refers to the database of
  Internet IP addresses and their associated names

50
TCP/IP (continued)

• Resource record is a single record that describes
  one piece of information in the DNS database
• An address resource record is a type of resource
  record that maps the IP address of an
  Internet-connected device to its domain name
• Approximately 20 types of resource records are
  currently used

51
TCP/IP (continued)

• Some TCP/IP Application Layer Protocols
• Telnet
• A terminal emulation protocol used to log on to
  remote hosts using the TCP/IP protocol suite
• Using Telnet, a TCP connection is established and
  keystrokes on the users machine act like
  keystrokes on the remotely connected machine
• Telnet is notoriously insecure

52
TCP/IP (continued)

• Some TCP/IP Application Layer Protocols
  (continued)
• File Transfer Protocol (FTP)
• Used to send and receive files via TCP/IP
• FTP commands will work from your operating
  systems command prompt
• Many FTP hosts accept anonymous logins

53
TCP/IP (continued)

• Trivial File Transfer Protocol (TFTP)
• Enables file transfers between computers, but it
  is simpler (or more trivial) than FTP
• TFTP relies on UDP at the Transport layer
• TFTP is useful when you need to load data or
  programs on a diskless workstation
• TFTP does not require a user to log on to a host

54
TCP/IP (continued)

• Network Time Protocol (NTP)
• Used to synchronize the clocks of computers on a
  network
• NTP depends on UDP for Transport layer services
• NTP is a protocol that benefits from UDPs quick,
  connectionless nature at the Transport layer
• NTP is time-sensitive and cannot wait for the
  error checking that TCP would require

55
TCP/IP (continued)

• Packet Internet Groper (PING)
• A utility that can verify that TCP/IP is
  installed, bound to the NIC, configured
  correctly, and communicating with the network
• PING uses ICMP services to send echo request and
  echo reply messages that determine the validity
  of an IP address
• By pinging the loopback address, 127.0.0.1, you
  can determine whether your workstations TCP/IP
  services are running

56
IPX/SPX

• Internetwork Packet Exchange/Sequenced Packet
  Exchange (IPX/SPX) is a protocol originally
  developed by Xerox
• Modified and adopted by Novell in the1980s for
  its NetWare network operating system
• Microsofts implementation of IPX/SPX is called
  NWLink

57
IPX/SPX (continued)

• The IPX and SPX Protocols
• Internetwork Packet Exchange (IPX) operates at
  the Network layer of the OSI Model and provides
  logical addressing and internetworking services,
  similar to IP in the TCP/IP suite
• IPX is a connectionless service because it does
  not require a session to be established before it
  transmits, and it does not guarantee that data
  will be delivered in sequence or without errors

58
IPX/SPX (continued)

• Sequenced Packet Exchange (SPX) belongs to the
  Transport layer of the OSI Model
• A connection-oriented protocol and therefore must
  verify that a session has been established with
  the destination node before it will transmit data

59
IPX/SPX (continued)

• Addressing in IPX/SPX
• IPX/SPX-based networks require that each node on
  a network be assigned a unique address to avoid
  communication conflicts
• IPX is the component of the protocol that handles
  addressing, addresses on an IPX/SPX network are
  called IPX addresses
• IPX addresses contain two parts the network
  address and the node address

60
NetBIOS and NetBEUI

• NetBIOS (Network Basic Input Output System) is a
  protocol originally designed for IBM to provide
  Transport and Session layer services for
  applications running on small, homogenous
  networks
• NetBEUI can support only 254 connections,
  however, and does not allow for good security
• Because NetBEUI frames include only Data Link
  layer (or MAC) addresses and not Network layer
  addresses, it is not routable

61
NetBIOS and NetBEUI (continued)

• Windows Internet Naming Service (WINS) - Provides
  a means of resolving NetBIOS names to IP
  addresses
• A computers NetBIOS name and its TCP/IP host
  name are different entities, though you can have
  the same name for both

62
NetBIOS and NetBEUI (continued)

• WINS has the same relationship to NetBIOS as DNS
  has to TCP/IP
• WINS does not assign names or IP addresses, but
  merely keeps track of which NetBIOS names are
  linked to which IP addresses

63
Appletalk

• The protocol suite originally designed to
  interconnect Macintosh computers
• An AppleTalk network is separated into logical
  groups of computers called AppleTalk zones

64
Appletalk (continued)

• An AppleTalk node ID is a unique 8-bit or 16-bit
  number that identifies a computer on an AppleTalk
  network
• An AppleTalk network number is a unique 16-bit
  number that identifies the network to which a
  node is connected

65
Binding Protocols on a Windows XP Workstation

• Binding is the process of assigning one network
  component to work with another
• You can manually bind protocols that are not
  already associated with a network interface

66
Summary

• Characteristics of TCP/IP, IPX/SPX, NetBIOS, and
  AppleTalk
• Network protocols correlate to layers of the OSI
  Model
• Core protocols of the TCP/IP suite and their
  functions

67
Summary (continued)

• The most popular protocol addressing schemes
• Purpose and implementation of the domain name
  system
• Install protocols on Windows XP clients