Chapter Eleven

1
Chapter Eleven

• Networking
• with TCP/IP
• and the Internet

2
IP Planning

• An IP address contains 32 bits or total of 4
  octets
• i.e. 192.168.0.2
• Each bit of the 32 bits can be a member of one
  and only one of the following sections
• Network
• Host
• Subnet
• What is the Network section?
• A group Identifier (compare to area code number)
• What is the Host section?
• Group of individual PCs or devices within the
  same network

3
IP Planning

• How many bits should be under the Network
  section?
• Depending on the size of the organization and
  potential growth, one of the following classes
  can be obtained from the ICANN organization A,
  B, or C

• How many bits should belong to the host section?
• 32 Network bits
• How many hosts can a Network have?
• (2 Number of host bits ) - 2

4
IP Planning

• Why are we loosing 2?
• Network Identifier
• Network Broadcast Address
• What is a Network Identifier?
• The first IP address in a network, known as the
  cable identifier. Represents the entire
  network. All host bits are turned off (0s)
• Example 192.168.4.0
• What class is it? What is it in binary?
• What is a Broadcast Address?
• The last IP address in a network. Used to
  communicate with all the hosts in the network.
  All host bits are turned on (1s)
• Example 192.168.4.255 What is it in binary?

5
IP Planning

• Examples
• Class A uses the first 8 bits for the network
  identifier
• The address range is only up to 126. The binary
  equivalent to that is 01111110. The MSB is 0 so
  we use only the last 7 bits.
• Number of networks that can be created 27 128
  2 126. Why?
• Number of hosts per Class A network
• 32 bits 8 bits 24 bits
• 224 16,777,216 2 16,777,214
• Class A structure N.H.H.H
• Class B uses the first 16 bits for the network
  identifier
• The address range is from 128 - 191. The
  difference is 64. The binary equivalent to
  that is 00111110.00000000 The first two MSB are
  0 so we use only the last 14 bits
• Number of networks that can be created 214
  16384
• Number of hosts per Class A network
• 32 bits 16 bits 16 bits
• 216 65,536 2 65,534
• Class B Structure N.N.H.H
• What would be Class C?

6
Exercise

• Classify the following IP addresses as A, B, or C
  and label the network and host parts of the IP
  address
• 99.1.1.0
• 156.1.149.9
• 171.13.5.233
• 127.1.1.255
• 193.4.14.1

7
IP Planning

• What is Subnetting?
• Process of subdividing a single class of network
  into multiple, smaller networks.
• Why do we need it?
• Organization, control, and ease of management
• Who does it?
• The Network Administrator of the organization
• How is subnetting done?
• Borrow bits from the host section and move them
  to the subnet section

• How many bits should I borrow?
• Depends on how many subnets you want to create
• What are some of the problems associated with
  subnetting?
• Loosing IPs
• The outside world does not have any knowledge of
  our Subnetting plan

8
IP Planning

• What is a Subnetmask?
• Special 32-bit number that, when combined
  (Logically Anded) with a devices IP address,
  determines which subnetwork that particular
  device belongs to

For an external host to communicate with
166.144.63.12, the router will need to interpret
the subnetmask information
9
IP Planning

• How is it written?
• All bits under the network and subnetwork
  sections are turned on (1s).
• What is default subnetmask?
• The subnet mask that will be used if you do not
  specify one in your TCP/IP Configuration
• 255.0.0.0 for Class A
• 255.255.0.0 for Class B
• 255.255.255.0 for Class C
• What is the relation between Subnet Mask and Bit
  Mask?
• Subnet mask is the dotted decimal notation of the
  number of network and subnetwork bits
• Bit Mask is the count of the number of network
  and subnet bits
• Default bit mask for class A is 8
• Default bit mask for class B is 16
• Default bit mask for class C is 24

10
IP Planning

• What are the rules?
• Number of subnets created
• 2 (Number of bits borrowed from the host
  section)
• Number of subnets Available
• 2 (Number of bits borrowed from the host
  section) 2
• Number of hosts created per subnet
• 2 (Number of bits remaining under the host
  section)
• Number of hosts available per subnet
• 2 (Number of bits remaining from the host
  section) 2

11
Agenda

• Attendance, and Review of subnetting rules
• Subnetting Class C -- Case Study
• Building the topology and Interconnecting
  Networking Devices Using real Cisco routers and
  switches
• Gateways What are they???
• Packet Tracer A quick introduction, and
  simulating how a packet traverses a simple WAN
  (How a packet goes from one LAN to another
  through routers)
• Subnetting Class C Group Exercise
• Logical And

12
Example

• Say you are assigned a Class C network number of
  200.133.175.0 (apologies to anyone who may
  actually own this domain address). You want to
  utilize this network across multiple small groups
  within an organization. You can do this by
  subnetting that network. Break this network into
  8 subnets of 32 IP addresses each.
• How many subnets can be used?
• How many nodes can be in each subnet?

13
Building the Topology

• Now, we will use real Cisco routers and switches
  to connect two LANs (Lets say, the HR department
  LAN and the IT department LAN)
• During this lab make sure that you take the time
  to do the following
• Check the different types of interfaces that a
  router can have
• Know what each type of an interface is used for
• Know what type of cable is used with each
  interface
• Ask Questions

14
Default Gateway

• The role of Routers in connecting subnets
• What is a Gateway?
• Combination of software and hardware that enable
  two different network segments to exchange data
• Examples Cisco Routers, Linksys routes, Linux
  servers with multiple NICs and routing services
  installed, windows 2000 server with multiple NICs
  and RRAS installed.
• The IP address of a routers port through which a
  network is connected to the router
• Every device has to have a default gateway to
  communicate with other devices outside its
  network

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(No Transcript)
16
Building The Topology with Packet Tracer

• Interconnect Devices
• Simulate how a Packet traverses a simple WAN

17
Group Exercise

• Do number 2 from the IP Addressing/Subnet Masking
  Problems

18
Agenda

• Attendance and questions from last weeks meeting
• Group discussion about the homework Exercise
• Logical AND and group exercise
• Case 1, and 2 (To be studied at home)
• Sockets, well-known port numbers, DNS, BOOTP,
  DHCP, and WINS
• Tools netstat, nbtstat, snlookup, and tracero

19
Logical And Why

• Why The logical AND function is used to
  extract the subnet ID from a host IP address and
  its subnet Mask
• Question With out using the table from the
  previous group exercise, can you tell to which
  subnet the host 200.133.175.199 belongs???

20
Logical And How

• Host IP Address (in binary format)
• AND
• Subnet Mask (in binary format)
• Subnet ID
• 1 And 1 1
• 1 And 0 0
• 0 And 0 0
• 0 and 1 0
• Short cut X And 255 X
• X And 0 0

21
Logical AND Exercise

• Given the IP Address 199.10.10.110/248
• What is the subnet mask?
• How many bits were borrowed?
• How many subnets were created
• What is the number of theoretical hosts per
  subnet?
• Using the Logical And function, find the subnet
  ID where the host resides
• What is the broadcast address for this subnet?

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Case 1

• Suppose you are given the IP address 195.5.5.0
  and wish to connect Springfield and Bedrock to
  Southpark. Create an IP addressing scheme that
  will meet the following requirements
• A Each subnet must support between 25 and 30
  devices.
• B You must have enough subnets to address each
  network.

• What is the subnet mask for this network?
• What is the broadcast address of the 3rd subnet?
• On the diagram, assign a subnet address to each
  network and give each router interface an
  appropriate IP address for that network.

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Case 1 Answer
24
Case 2

• Given the IP address 199.199.199.172 with a
  subnet mask of 255.255.255.192. Answer the
  following
• How many bits were borrowed?
• How many subnets have been created?
• How many host address per subnet?
• What is the subnet address of the network
  containing the given IP address?
• What is the broadcast address of the network
  containing the given IP address?

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Case 2 Answer
A 2 B 4 C 64 D 199.199.199.128 E
199.199.1299.191
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Sockets and Ports

• Socket
• Logical address assigned to a specific process
  running on a computer

27
Sockets and Ports
Virtual circuit for the Telnet service
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Host Names and Domain Name System (DNS)

• Host name
• Symbolic name that describes a TCP/IP device
• Domain
• Group of computers that belong to the same
  organization and have part of their IP addresses
  in common
• Domain name
• Symbolic name that identifies an organization
• Must be registered with the Internet Naming
  Authority.
• Must be available (not already taken by another
  organization)

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Domain Names

• Fully qualified domain name (FQDN)
• Name of a host that includes the full domain name
  as well as the host name
• Example You work at the library of congress and
  named your machine PeggySue. Your fully
  qualified hostname is PeggySue.loc.gov
• Top-level domains (TLDs)
• Highest-level category used to distinguish domain
  names
• A certain suffix that applies to an organization
  according to the nature of business it conducts.

30
Domain Names
Domain naming conventions
What other domains are now available?
31
Host Files

• Text file that associates TCP/IP host names with
  IP addresses
• (was used when we had 1000 hosts on the web)
• Alias
• Nickname for a nodes host name

Example host file This file is called lmhosts
in Windows and /etc/hosts on a UNIX-based
computer
32
Domain Name System (DNS)

• Database that is distributed over several key
  computers across the Internet.
• Hierarchical way of tracking domain names and
  their addresses, devised in the mid-1980s
• Example How does the DNS request is processed?
• From Local, Regional, National To National,
  Regional, Organizational (local)

DNS server hierarchy by geography
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Domain Name System (DNS)

• Resolvers
• Hosts on the Internet that need to look up domain
  name information
• Example, type the command telnet
  support.novell.com and your Telnet client
  software will kick off the resolver service to
  find the IP address for support.novell.com
• Name servers are servers that contain databases
  of names and their associated IP addresses
• Each name server manages a group of devices,
  collectively known as a zone

34
Configuring DNS

• To view or change the name server information on
  a Windows 2000PC
• Right-click My Network Places, then right-click
  appropriate Network Adapter.
• Select Properties, Select TCP/IP, Select
  Properties.
• In the TCP/IP Properties box, click the DNS tab.

DNS Configuration properties tab
35
DNS Name Space

• Name space
• Database of Internet IP addresses and their
  associated names distributed over DNS name
  servers worldwide (every name server holds a
  piece of that database)
• Root server
• DNS server maintained by InterNIC and acts as the
  ultimate authority on how to contact the
  top-level domains (how to get from .edu to .com)
• Resource record
• One record for each host
• Element of a DNS database stored on a name server
  that contains information about TCP/IP host names
  and their addresses

36
Bootstrap Protocol (BOOTP)

• Service that simplifies IP address management.
• Requires network administrators to enter every IP
  and MAC address into the BOOTP table

• This situation is ideal for Diskless
  workstations workstations that do not contain
  any hard disks

37
Dynamic Host Configuration Protocol (DHCP)

• Automated means of assigning a unique IP address
  to every device on a network
• Reasons for implementing DHCP
• Reduce the time and planning spent on IP address
  management
• Reduce the potential for errors in assigning IP
  addresses
• Enable users to move their workstations and
  printers without having to change their TCP/IP
  configuration
• Make IP addressing transparent for mobile users

38
DHCP Leasing Process

• Lease
• Agreement between DHCP server and client on how
  long the client will borrow a DHCP-assigned
  address

39
NetBIOS Names Defined

• Each Windows-based host receives a NetBIOS name
  during the installation of the operating system.
  This name is used to uniquely identify the
  machine on the network
• However the NetBIOS name is not used itself to
  identify a host it is used by NetBIOS
  applications and processes to establish
  communication with other NetBIOS applications on
  remote hosts
• A NetBIOS name consists of 15 alphanumeric
  characters
• If a NetBIOS name does not contain 15 characters
  to fill the name out to the required 15
  characters, Windows will add the necessary number
  of null characters to fill the name out to the
  required 15 characters
• A sixteenth character , which is not usually
  visible, is added to each NetBIOS name to
  indicate the type of name, service, or group that
  the NetBIOS name represents

40
Registration, Discovery and Release of NetBIOS
Names
41
LMHOSTS File

• Standard Text file used to resolve NetBIOS names
  to IP addresses.
• The LMHOSTS file should be located in
• systemroot\system32\drivers\etc directory
• Example
• 192.168.0.1 BONGO PRE DOM Resource
• The LMHOSTS file is read from top to bottom. So
  would the order of entries matter???

42
NetBIOS Node Types

• B-Node relies completely on broadcast for name
  registration, discovery and release. Creates
  great deal of traffic on the network
• Cache, Broadcast, End
• P-Node Point-to-point communication with a WINS
  server for NetBIOS name services
• Cache, WINS, End
• H-Node default configuration in windows machine
• Cache, WINS, Broadcast up to 3 requests, LMHOST
  if exist, End

43
NetBIOS Names and Browsing The Network Resources

• How do I get to see all these network resources
  when I click on My Network Places???
• What is a browse List? A list of available
  NetBIOS network resources for a particular
  network segment.
• How are the lists built and who keep them?
• NetBIOS machines announce their presence at the
  start up then once every 12 minutes. Those
  announcements will be used by the following
  special hosts to built the browse lists
• Master Browser One per segment
• Backup Master Browser Future Master browser
• Domain master Browser Pulls the master browser
  to get a list of the resources on this particular
  segment, then sends a complete list with all the
  resources on the entire network to each Master
  Browser

44
NetBIOS Switches
45
Windows Internet Naming Service (WINS)

• Provides a means of resolving NetBIOS names with
  IP addresses
• What are NetBIOS names?
• How are DNS names different from NetBIOS?
• Make sure that you can differentiate between
  TCP/IP host names and NetBIOS names
• Remember that NetBIOS is used primarily with
  Windows-based systems
• WINS offers several advantages
• Guarantees a unique NetBIOS name is used for each
  computer on a network
• Support for DHCP
• Better network performance (eliminates NetBIOS
  broadcast)

46
TCP/IP Troubleshooting

• Packet Internet Groper (PING)
• Troubleshooting utility that can verify TCP/IP is
  installed, bound to the NIC, configured
  correctly, and communicating with the network
• How does it work? It uses ICMP to send echo
  request and echo replay messages.
• What is an Echo Request? An echo request is a
  signal sent out to another computer
• What is an Echo Replay? An echo reply is the
  other computers response signal
• Process of sending this signal back and forth is
  known as pinging

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Netstat and Nbstat

• Netstat
• Displays statistics and the state of current
  TCP/IP connections
• Nbstat
• Provides information about NetBIOS names and
  their addresses

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Nslookup and Traceroute

• Nslookup
• Allows you to look up the DNS host name of a
  network node by specifying its IP address, or
  vice versa. Used to troubleshoot problems related
  to the DNS server.
• Tracert
• Uses ICMP and TTL to trace the path from one
  networked node to another
• What is TTL? Numeric measure used to determine
  how many more network hops a datagram can make.
  When TTL expires a datagram returns to the source
  with the identity of the destination.
• How is it done? By transmitting a series of UDP
  to a specified destination

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Next Meeting (After Spring Break)

• Take Chapter 11 Test (Read the chapter first)
• Take The Midterm Exam (Make sure that you study
  both case 1, and 2 before you take the test
• Download the Project and start working on it It
  is due two weeks before the final exam!
• Make sure that you have the cable kit
• Read Chapter 6 (Network Hardware)
• Enjoy your break