Chapter Eleven

1
Chapter Eleven

• Networking
• with TCP/IP
• and the Internet

2
Chapter Objectives

• Discuss additional details of TCP/IP addressing
  and subprotocols
• Understand the purpose and uses of BOOTP, DHCP,
  WINS, DNS, and host files
• Use TCP/IP protocols for network troubleshooting
• Understand and use TCP/IP applications such as
  Internet browsers, e-mail, and e-commerce

3
Addressing and Name Resolution

• IP Addressing
• An IP address is 32 bits in size
• Every IP address is grouped into four 8-bit
  octets
• Octets are separated by decimal points
• Valid octet numbers range from 0 to 255 and
  represent a binary address

4
IP Addressing

• IP Addressing (cont.)
• Each address consists of two parts network and
  host
• The network portion of an address indicates
  whether the device belongs to a Class A, B, C, D,
  or E network
• Some octet number are reserved for special
  functions
• Dotted decimal notation
• Shorthand convention used to represent IP
  addresses and make them more easily readable by
  people

5
Network Classes
FIGURE 11-1 IP addresses and their classes
6
Network Classes
TABLE 11-1 Three commonly used classes of TCP/IP
networks

• Multicasting
• Allows one device to send data to a specific
  group of devices (not the entire network segment)

7
Subnetting

• Process of subdividing a single class of network
  into multiple, smaller networks

FIGURE 11-2 IP address before and after subnets
8
Subnetting

• Extended network prefix
• The combination of an addresss network and
  subnet information
• Subnet mask
• Special 32-bit number that, when combined with a
  devices IP address, informs the rest of the
  network about the network class to which the
  device is attached
• Follows same dotted quad format
• 1s specify extended network prefix
• 0s specify host

9
Subnetting
FIGURE 11-3 Subnetted IP address and its subnet
mask
10
Subnetting
FIGURE 11-4 Subnetted network connected to the
Internet
11
Subnetting
FIGURE 11-5 Network with several subnets
12
Subnetting
FIGURE 11-6 Data traveling over subnets
13
Gateways

• Combination of software and hardware that enable
  two different network segments to exchange data
• Every device has a default gateway
• First interprets its outbound requests and last
  interprets its inbound requests to and from other
  subnets
• Core Gateways
• Gateways that make up the Internet backbone

14
Gateways
FIGURE 11-7 Use of default gateways
15
Subnetting

• Defining your own subnet(s)
• Lets review decimal value of bit positions
• Ex. 01110001 ? 64 32 16 1 113

16
Subnetting

• Example creating subnets on a Class A network
• 1st octet can be 1-126 use 10.0.0.0
• 1st octet defines network address that leaves 24
  bit positions yet for node information
• of node addresses available is 224 2
  16,777,214 (-2 for broadcast and network)
• Determine the number of subnets needed (e.g. 30)
• Each w/ own router interface

17
Subnetting

• Create the subnet mask
• Steal bits from the node octets (for our example,
  use 2nd octet)
• Determine the lower order bits needed to create
  the subnets and then add the same number of
  higher order bits to create the subnet mask
• Well need 5 bits (124816) 1 30
• -1 is a reserved bit used to determine 0 or 255
• Calculate subnet mask ? 1286432168 248
• 255.248.0.0 is our new subnet mask
• We can use this to compute our range of IP
  addresses
• Slash notation (classless) 255.248.0.0 /13

18
Subnetting

• Calculating IP subnet ranges
• Use lowest high order bit equivalent as both our
  starting subnet number and our increment value
• Notice the lack of 10.8.0.0 and 10.15.255.255

19
Subnetting

• Calculate the of available host addresses
• We stole 5 bits for the subnet mask, so that
  leaves us 19 (32 13)
• 19 is the number of possible bits after all high
  order bits
• To calculate we take 219 2 524,286 IP
  addresses per subnet

20
Subnetting

• Subnetting tables

21
Subnetting

• JC config
• Subnet mask 255.255.240.0 (4 bits used)
• Slash notation?
• Default gateway 172.16.16.1
• 172.16.16.1 172.16.31.254
• 172.16.32.1 172.16.47.254
• 172.16.224.1 172.16.239.254
• Total of 4094 possible nodes per subnet