21-IP addressing by uth65747

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									21-IP addressing

Dr. John P. Abraham
      Professor
       UTPA
          Chapters 19, 20
• I have already covered these concepts
  elsewhere.
             Addressing
• Physical
• Logical
                  IP address
• 32 bits
  – Hierarchy – prefix and suffix
  – Prefix identifies the network – given by IANA
    In classful addressing, the network address (the
        first address in the block) is the one that is
         assigned to the organization. The range of
     addresses can automatically be inferred from the
                     network address.

  – Suffix identifies the computer –given locally
  – No two computers can have the same public IP
       Classful IP addressing
• Divided IP address space into three
  primary classes A, B, C and also there
  exist class D (multicasting) and E.
• First four (MSB) bits will determine its
  class
              Lea    Size of     Size of    Number     Addresse       Start      End
  Class       ding   Network      Rest        of          s          addres    address
              Bits   Number        Bit     Networks      per            s
                     Bit field    field                Network


Class A         0      8           24         128        16,777,     0.0.0.0   127.255.
                                            7                24
                                           (2 )        216 (2 )                255.255

Class B        01      16          16        16,384      65,536      128.0.0. 191.255.
                                            14          16
                                           (2 )        (2 )          0        255.255

                                                                 8
Class C       110      24          8         2,097,1     256 (2 )    192.0.0. 223.255.
                                                21
                                           52 (2 )                   0        255.255

Class D       1110     not         not       not         not         224.0.0. 239.255.
(multicast)          defined     defined   defined     defined       0        255.255

Class E       1111     not         not       not         not         240.0.0. 255.255.
(reserved)           defined     defined   defined     defined       0        255.255
Finding the address class
Figure 4.5   Finding the class in decimal notation
Find the class of each address:
    a. 227.12.14.87      b.193.14.56.22       c.14.23.120.8
d. 252.5.15.111       e.134.11.78.56

                              Solution
a. The first byte is 227 (between 224 and 239); the class is D.
b. The first byte is 193 (between 192 and 223); the class is C.
c. The first byte is 14 (between 0 and 127); the class is A.
d. The first byte is 252 (between 240 and 255); the class is E.
e. The first byte is 134 (between 128 and 191); the class is B.
          Subnet Addressing




• The network address is the beginning
  address of each block. It can be found by
  applying the default mask to any of the
  addresses in the block (including itself). It
  retains the netid of the block and sets the
  hostid to zero.
     Example 12


Given the address 23.56.7.91, find the beginning address
(network address).




                            Solution
The default mask is 255.0.0.0, which means that only the first
byte is preserved and the other 3 bytes are set to 0s. The
network address is 23.0.0.0.
     Example 15


What is the subnetwork address if the destination address is
200.45.34.56 and the subnet mask is 255.255.240.0?


 Solution
 We apply the AND operation on the address and the subnet
 mask.
Address            ➡ 11001000 00101101 00100010 00111000
Subnet Mask        ➡ 11111111 11111111 11110000 00000000
Subnetwork Address ➡ 11001000 00101101 00100000 00000000.
Figure 4.25   Comparison of a default mask and a subnet mask
Table 4.3 Special addresses




                        Private IPs
            CIDR notation
• Classless Inter-Domain routing (CIDR)
• Ddd.ddd.ddd.ddd/m 192.5.48.69/26

								
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