Network Guide to Networks, Fourth Edition - PowerPoint PPT Presentation


PPT – Network Guide to Networks, Fourth Edition PowerPoint presentation | free to download - id: 2208bc-ZDc1Z


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

Network Guide to Networks, Fourth Edition


Network Guide to Networks, Fourth Edition. Chapter 11. In-Depth TCP/IP Networking ... Network Guide to Networks, 4e. 4. Classful Addressing. Adheres to ... – PowerPoint PPT presentation

Number of Views:263
Avg rating:3.0/5.0
Slides: 48
Provided by: cltAs


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Network Guide to Networks, Fourth Edition

Network Guide to Networks, Fourth Edition
  • Chapter 11
  • In-Depth TCP/IP Networking

Designing TCP/IP-Based Networks
  • Review of some TCP/IP fundamentals
  • IP is a routable protocol
  • On a network using TCP/IP, each interface
    associated with unique IP address
  • Some nodes may use multiple IP addresses
  • IP addresses consist of four 8-bit octets
  • Many networks assign IP addresses and host names
    dynamically, using DHCP
  • Every IP address can be associated with a network

  • Separates network into multiple, logically
    defined segments (subnets)
  • Each subnets traffic separated from every other
    subnets traffic
  • Enhances security
  • Subnetworks must be connected via routers or
    other Layer 3 devices
  • Improves performance
  • Data is selectively retransmitted
  • Simplifies troubleshooting

Classful Addressing
  • Adheres to network class distinctions
  • Only Class A, B, and C addresses are recognized
  • Network ID limited to first 8 bits in Class A,
    first 16 bits in Class B, and first 24 bits in
    Class C
  • Fixed network ID size ultimately limits number of
    hosts a network can include

Classful Addressing (continued)
Figure 11-1 Example IP addresses with classful
Subnet Masks
  • Subnetting depends on subnet masks to identify
    how a network is subdivided
  • Indicates where network information is located in
    an IP address
  • 1 bits indicate corresponding bits in IP
    address contain network information
  • 0 bits indicate corresponding bits in IP
    address contain host information
  • To calculate hosts network ID given IP address
    and subnet mask, perform ANDing

Subnet Masks (continued)
Table 11-1 Default subnet masks
Subnet Masks (continued)
Table 11-2 ANDing
Figure 11-2 Example of calculating a hosts
network ID
Reserved Addresses
  • Certain types of IP addresses reserved for
    special functions
  • In network IDs, bits for host information set to
  • In broadcast addresses, octet(s) representing
    host information set to all 1s (255 in decimal

Subnetting Techniques
  • Subnetting breaks rules of classful addressing
  • Some bits that in classful addressing would
    represent host information changed to represent
    network information
  • Reduce number of usable host addresses per subnet

Subnetting Techniques (continued)
Table 11-3 Class B subnet masks
Subnetting Techniques (continued)
Table 11-4 Class C subnet masks
Calculating Subnets
  • Formula for determining how to modify a default
    subnet mask 2n-2Y
  • n number of bits in subnet mask that must be
    switched from 0 to 1
  • Y number of subnets that result
  • Extended network prefix Additional bits used for
    subnet information plus existing network ID
  • Class A, B, and C networks can all be subnetted
  • External routers pay attention to only the
    network portion of devices IP addresses

Calculating Subnets (continued)
Figure 11-3 A router connecting several subnets
Calculating Subnets (continued)
Figure 11-3 (continued) A router connecting
several subnets
CIDR (Classless Interdomain Routing)
  • Classless routing or supernetting
  • Provides additional ways of arranging network and
    host information in an IP address
  • Supernet Subnet created by moving subnet
    boundary to the left
  • Generates more usable IP addresses
  • CIDR notation (slash notation) network ID
    followed by forward slash (/), followed by number
    of bits used for extended network prefix
  • CIDR Block

CIDR (continued)
Figure 11-4 Subnet mask and supernet mask
Figure 11-5 Calculating a hosts network ID on a
supernetted network
Internet Gateways
  • Combination of software and hardware enabling two
    different network segments to exchange data
  • Every device on a TCP/IP-based network has a
    default gateway
  • First interprets outbound requests to other
  • Interprets inbound requests from other subnets
  • Each node on network has one default gateway
  • May be network interface on a router
  • Must maintain routing tables as well
  • Core gateways make up the Internet backbone

Internet Gateways (continued)
Figure 11-6 The use of default gateways
NAT (Network Address Translation)
  • Default gateways can be used to hide IP numbers
    assigned within an organization
  • Clients behind gateway may use any IP addressing
  • Even non-legitimate schemes
  • Must have legitimate IP address to exchange data
    with Internet
  • NAT when clients transmission reaches default
    gateway, it assigns clients transmission a valid
    IP address

NAT (continued)
Figure 11-7 NAT through an Internet gateway
ICS (Internet Connection Sharing)
  • Computer with Internet access (ICS host)
    configured to translate requests to and from
    Internet on behalf of other computers on network
  • Acts as DHCP server, DNS resolver, and NAT
    gateway for clients on its LAN
  • Network adapter on ICS host assigned IP address
  • Clients must be set up to obtain IP addresses
  • ICS host assigns clients IP addresses in range of through

Intranets and Extranets
  • Intranet network or part of network that uses
    browser-based services to exchange information
    within an enterprise
  • Used for supplying HTTP-accessible documents,
    e-mail, file sharing, document management, and
  • Defined by its security policies
  • Extranet network that uses Internet-like
    services and protocols to exchange information
    within an organization and with certain,
    authorized users outside of that organization

TCP/IP Mail Services
  • E-mail is most frequently used Internet service
    that network administrators manage
  • Mail servers communicate with other mail servers
    to deliver messages across Internet
  • Hundreds of software packages for mail servers
  • Sendmail, Microsoft Exchange Server, Lotus Notes,
    Novell Groupwise
  • Mail clients send/retrieve messages to/from mail
  • Servers and clients communicate through TCP/IP
    Application layer protocols

SMTP (Simple Mail Transfer Protocol)
  • Protocol responsible for moving messages between
    mail servers over TCP/IP-based networks
  • Belongs to Application layer of TCP/IP Model
  • Relies on TCP at Transport layer
  • Operates from port 25
  • Relies on higher-level programs for instructions
  • Can only transport or hold mail
  • When configuring clients to use Internet e-mail,
    must identify users SMTP server

MIME (Multipurpose Internet Mail Extensions)
  • Standard SMTP message format allows for lines
    that contain 1000 ASCII characters max
  • Cannot handle pictures or formatted text
  • MIME standard for encoding and interpreting
    binary files, images, video, and non-ASCII
    character sets within e-mail messages
  • Identifies each element of a message according to
    content type
  • Works in conjunction with SMTP

POP (Post Office Protocol)
  • Application layer protocol used to retrieve
    messages from mail servers
  • POP3 is most current and commonly used version
  • Mail delivered and stored on mail server until
    user connects (via e-mail client) to retrieve
  • Mail deleted from server after retrieval
  • Minimizes use of server resources
  • Best suited to users who retrieve mail from same
    workstation all the time

IMAP (Internet Message Access Protocol)
  • Developed as sophisticated alternative to POP3
  • IMAP4 is most current version
  • Users can store messages on mail server
  • IMAP4 provides the following features
  • Retrieve all or only a portion of any mail
  • Review messages and delete them while the
    messages remain on the server
  • Create sophisticated methods of organizing
    messages on the server
  • Share mailboxes in a central location

Additional TCP/IP Utilities
  • TCP/IP comes with complete set of utilities that
    can help to track down most TCP/IP-related
  • e.g., Ping, Telnet, ARP
  • Nearly all TCP/IP utilities can be accessed from
    command prompt on any type of server or client
    running TCP/IP
  • Syntax may differ depending on OS
  • Options may differ according to OS

  • Displays TCP/IP statistics and details about
    TCP/IP components and connections on a host
  • Port on which a particular TCP/IP service is
  • Network connections currently established
  • Number of packets handled by network interface
    since activation
  • Number of data errors

Netstat (continued)
  • Common Netstat switches
  • -a lists all available TCP and UDP connections
  • -e displays details about all packets that have
    been sent
  • -n lists currently connected hosts according to
    their ports and IP addresses (in numerical form)
  • -p allows you to specify what type of protocol
    statistics to list
  • -r provides list of routing table information
  • -s provides statistics about each packet
    transmitted by a host, separated according to
    protocol type

  • Given NetBIOS name, get IP address
  • Common nbtstat switches
  • -a displays a machines name table given its
    NetBIOS name
  • -A displays a machines name table given its IP
  • -r lists statistics about names that have been
    resolved to IP addresses by broadcast and by WINS
  • -s displays a list of all the current NetBIOS
    sessions for a machine

  • Query DNS database from any network computer and
    find host name of a device by specifying its IP
    address, or vice versa
  • Provides hosts IP address, primary DNS server
    name, and address holding record for this name
  • Many options (switches)

  • Domain information groper (dig) similar to
  • Provides more detailed information than nslookup
  • e.g., specifics about resource records associated
    with host name
  • Many switches
  • Must be explicitly installed on Windows systems

Dig (continued)
Figure 11-11 Output of a simple dig command
  • Query DNS registration database and obtain
    information about a domain
  • Who is domain registered to?
  • Technical person responsible for domain?
  • Hosting entity?
  • DNS Server addresses?
  • Must install software to use on Windows systems
  • Web-based alternatives exist
  • e.g.,

Traceroute (Tracert)
  • Uses ICMP to trace path from one node to another
  • Identifies all intermediate hops
  • Useful for determining router or subnet
    connectivity problems
  • Transmits series of UDP datagrams to specified
  • Increases TTL as path is discovered
  • Traceroute may stop before completing
  • Device problem on path
  • Device does not accept ICMP transmissions
  • Often indicates firewall

  • TCP/IP administration utility for use with
    Windows NT, 2000, XP, and Server 2003 OSs
  • Provides information about network adapters IP
    address, subnet mask, and default gateway
  • Commonly used switches
  • /? displays list of available switches
  • /all displays complete TCP/IP configuration
    information for each network interface on device
  • /release releases DHCP-assigned addresses for all
    network interfaces
  • /renew renews DHCP-assigned addresses for all
    network interfaces

  • Same as ipconfig utility, but applies to Windows
    9x and Me OSs
  • Graphical interface

  • TCP/IP configuration and management utility used
    on UNIX-type of systems
  • Similar to ipconfig on Windows systems
  • Commonly used switches
  • -a applies command to all interfaces on a device
  • down marks interface as unavailable to network
  • up reinitializes interface after it has been
    taken down
  • Complete list of switches found in man pages

VoIP (Voice over IP)
  • Use of packet-switched networks and TCP/IP to
    transmit voice conversations
  • IP telephony
  • Objectives for implementing VoIP
  • Lower costs for voice calls
  • Supply new or enhanced features and applications
  • Centralize voice and data network management

VoIP (continued)
  • VoIP callers can use
  • Traditional telephone
  • IP telephones telephones designed for TCP/IP
  • Softphones computers equipped with microphone,
    speaker, and VoIP client software
  • IP telephones must have unique IP addresses
  • More difficult to transmit voice signals over a
    packet-switched network than data signals
  • Internet telephony VoIP carried via Internet
  • May also be carried over private lines

VoIP (continued)
Figure 11-16 Accessing a VoIP network from
traditional telephones
  • Subnetting separates one network or segment into
    multiple, logically defined segments, or subnets
  • Bits in a subnet mask that equal 1 indicate that
    corresponding bits in an IP address contain
    network information
  • Bits in a subnet mask that equal 0 indicate that
    corresponding bits in an IP address contain host
  • CIDR allows the creation of supernets, or subnets
    established by using bits that normally would be
    reserved for network class information

Summary (continued)
  • Gateways facilitate communication between
    different subnets
  • Every device on a TCP/IP-based network has a
    default gateway
  • NAT allows a network administrator to hide IP
    addresses assigned to nodes on a private network
  • ICS is a service that allows a network of
    computers to share a single Internet connection
    through an ICS host computer

Summary (continued)
  • SMTP is responsible for moving messages from one
    e-mail server to another over TCP/IP-based
  • POP is a mail retrieval protocol
  • IMAP4 allows users to store messages on the mail
    server, rather than always having to download
    them to the local machine
  • The netstat utility displays TCP/IP statistics
    and the state of current TCP/IP components and

Summary (continued)
  • The nslookup utility allows you to look up the
    DNS host name of a network node by specifying the
    nodes IP address, or vice versa
  • The traceroute utility useful for determining
    router or subnet connectivity problems
  • VoIP is the use of packet-switched TCP/IP-based
    networks to carry voice signals