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					Internet Protocol Address



                        Kittipong Warasup
                 kittipong@sit.kmutt.ac.th
               What we will learn




Internet Protocol Address           2
               What is an IP address?

           IP address is requires for each host on a TCP/IP
            internetwork.
                 To access other devices on the network.
                 To network component.
                 To manage the device.
           The IP address must be unique across the entire
            internetwork.
           Internet Assigned Number Authority (IANA) is in
            charge of how IP addresses are assigned.



Internet Protocol Address                                      3
               Duplicate IP Address

           The second host with the duplicate IP address
            has its IP stack disabled.
           A warning message is issued to both host.
           Both host continue to use the same IP address.




Internet Protocol Address                                    4
               IP Address Representation
           There are two form
                 Binary representation
                 Dotted-decimal Notation
           On a single network segment, all hosts share the same
            network prefix, but must have a unique host number.
           On different network segment, hosts have different
            network prefixes, but may have the same host number.



                            Network Number   Host Number




Internet Protocol Address                                           5
               Binary Representation

           Each IP address is a stream of 32 1s and 0s.
                11000000101010000111100011111111
           We only work with up to eight digits.
           The largest value allowed for an octet is
            11111111 which is 255 in decimal.
           The lowest value allowed for an octet is
            00000000 which is 0.




Internet Protocol Address                                  6
                Dotted-Decimal Notation

           An IP address comprises four octets which make
            up the 32-bit address.
           Octets are written in decimal notation and
            separated using dot between each other.
         Bit#         0                                       31

                      11000000 . 10101000 . 01111000 . 01100100




                               192 . 168 . 120 . 100

Internet Protocol Address                                          7
               IP Address Classes
           There are five pools of IP addresses designated as classes
            of IP addresses.
           Each of the first three classes of IP addresses is composed
            of a network and host portion of those IDs.

                      Class A   Net   Host   Host   Host


                      Class B   Net   Net    Host   Host


                      Class C   Net   Net    Net    Host


                      Class D          Multicast


                      Class E          Reserved

Internet Protocol Address                                             8
               Class A Address

           Class A network address has an 8-bit network
            prefix and 24-bit host number.
           The highest order bit set to 0.
           The rest 7-bit of first octet creates unique
            network ID.
           The last three octets left for the host ID.

                        0


                        Network Number   24-bit Host Number



Internet Protocol Address                                     9
               Class B Address

           Class B network address has an 16-bit network
            prefix and 16-bit host number.
           The two highest order bit set to 10.
           The rest 6-bit of first octet and the next octet
            create unique network ID.
           The last two octets left for the host ID.

                        1 0


                              Network Number   16-bit Host Number



Internet Protocol Address                                           10
               Class C Address

           Class C network address has an 24-bit network
            prefix and 8-bit host number.
           The three highest order bit set to 110.
           The rest 5-bit of first octet and the next two
            octets create unique network ID.
           Only the last octet left for the host ID.

                        1 1 0


                                Network Number   24-bit Host Number



Internet Protocol Address                                             11
               Class D Address

           Class D addresses are reserved for multicast
            group, not assigned to individual hosts.
           The four highest order bit set to 1110.
           First octet of Class D value between 224 and 239.
           The remaining 28 bits represent the multicast
            group.

                        1 1 1 0


                                     24-bit Multicast Group



Internet Protocol Address                                     12
               Class E Addresses

           Class E addresses are experimental addresses,
            not available to the public.
           They have been reserved for future use.
           The four highest order bit set to 1111.
           First octet of Class E value between 240 and 255.


                       1 1 1 1 0




Internet Protocol Address                                   13
               Special IP Addresses
           Some IP addresses have been reserved and cannot be assigned to
            individual hosts.
           IP addresses with the host ID set to all 0s represent a network
            address.
           IP addresses with the host ID set to all 1s represent a network’s
            broadcast.
           The network address 127 is reserved for loopback functions.


    Class Network Address Broadcast Address Example
    A           x.0.0.0         x.255.255.255        125.0.0.0, 125.255.255.255
    B           x.y.0.0         x.y.255.255          131.1.0.0, 131.255.255.255
    C           x.y.z.0         x.y.z.255            202.1.1.0, 202.255.255.255


Internet Protocol Address                                                       14
               Local Network Address
           Three pools of IP addresses have been reserved for use on local
            network.
                 10.0.0.0 through 10.255.255.255
                 172.16.0.0 through 172.31.255.255
                 192.168.0.0 through 192.168.255.255
           These IP addresses are not in use on the internet.
           They only can be used behind firewalls and proxy servers that hide
            them from the internet.

                                                                     202.44.8.40


                    Interne
                       t

                                        Firewall/
                  External Network    Proxy Server
                                                         Internal Network

Internet Protocol Address                                                          15
               IP Address Class Summary
 IP                                         High –     Address        Number of
                            Purpose                                  Bits Network/
 Address          Format                    Order       Range                        Max. Hosts
 Class                                      Bit (s)                       Host
                            Few large
 A               N.H.H.H                       0       1.0.0.0 to                    16,777,214
                            Organizations                                7/24
                                                       126.0.0.0                       (224-2)

 B               N.N.H.H    Medium - size
                                              1,0      128.1 to                        65,543
                            Organizations                               14/16
                                                      191.254.0.0                      (216-2)

 C               N.N.N.H    Relatively
                                             1,1,0    192.0.1.0 to
                            Small                                        22/8
                                                       223.255.                       254(28-2)
                            Organizations
                                                        254.0
                                                                        Not for
 D                    -     Multicast                                 commercial
                                                      224.0.0.0 to
                            Groups (RFC                                  use
                                            1,1,1,0   239.255.255                         -
                            1112)
 E                    -                                240.0.0 to          -
                            Experimental                254.255.
                                            1,1,1,1                                       -
                                                        255.255
Internet Protocol Address                                                                         16
               Subnet Masks

           Subnet masks designate which bits of an IP
            address represent the network portion and which
            bits represent the host portion.
           Default subnet masks are:
                 Class A is 255.0.0.0
                 Class B is 255.255.0.0
                 Class C is 255.255.255.0




Internet Protocol Address                                 17
               The ANDing Process
           When two hosts attempts to communicate with each other, the
            source uses its subnet mask to determine whether the destination is
            on the local network or a remote network.




                                                    192.168.1.20
                                                    255.255.255.0
                             192.168.1.10
                             255.255.255.0


       Host A’s IP address 11000000 10101000 00000001 00001010
       Host A’s subnet mask 11111111 11111111 11111111 00000000
       ANDing Result      11000000 10101000 00000001 00000000
       Host B’s IP address 11000000 10101000 00000001 00010100
       Host B’s subnet mask 11111111 11111111 11111111 00000000
       ANDing Result      11000000 10101000 00000001 00000000
Internet Protocol Address                                                         18
               General Guidelines for IP Addressing

           All hosts on the same physical network should
            have the same network ID.
           Each host on a network segment must have a
            unique host portion of the IP address.
           A network ID never be 127.x.x.x .
           A host ID cannot be all 1s.
           A host ID cannot be all 0s.




Internet Protocol Address                                   19
               Limitations of Classful Addressing

           No network class was designed to support
            medium-sized organizations.
           Allocation of IP address is not efficient.
           It causes depletion of the network address space.
           The size of the global Internet’s routing table is
            increasing.




Internet Protocol Address                                    20
               Subnetting Solution
           There are a situations that require you to segment the
            network using a subnet mask that is not the default
            subnet mask.
           The host portion is now broken into a subnet portion and
            host portion
            Two-level Classful

                            Network Number                  Host Number



            Three-level Subnet

                            Network Number           Subnet Number   Host Number


                                 Extended Network Prefix

Internet Protocol Address                                                          21
               Subnet Designing

           Before design, the following questions must be
            answered.
                 How many network segments does the network need
                  addresses for today and in the future?
                 How many hosts will be needed on the largest segment
                  of the network today and the future?
           Three steps for subnet designing.
                 Determining the number of subnets.
                 Determining the number of hosts.
                 Establishing the available pools of IP addresses.


Internet Protocol Address                                             22
               Determining the Number of Subnets

           Each individual network segment requires a
            unique network number.

                               Net#1   Net#2




                                               Net#3
                       Net#4




Internet Protocol Address                                23
               Zero Subnetting

           The subnetwork addresses of all zeros or all ones
            are not allowed in many networking
            implementations.
           Zero subnetting is a feature that allows routers
            supporting advanced routing protocols to use the
            subnetwork addresses of all zeros and all ones.




Internet Protocol Address                                   24
               Determining the Number of Hosts

           Number of hosts is calculated by the bits left from
            the first step using the following formula.
                                  2n – 2

           The “n” is the number of bits left.
           The number 2 is subtracted because a host
            address cannot be all zeros or all ones.




Internet Protocol Address                                     25
               Establishing the Pools of IP Addresses

           The final step is to identify the actual address
            that can be assigned to hosts in the network
            segments.
           Two IP addresses cannot be used.
                 The first address, which all host IDs are zero, is the
                  network address.
                 The last address, which all host IDs are one, is the
                  broadcast address.
           The available pool begins with the address
            immediately following the network address and
            ends with the address before the broadcast
            address.
Internet Protocol Address                                                  26
               Variable-Length Subnet Masking

           VLSM enables each subnet to have its own unique
            subnet mask.
           If the subnet mask is not included in the routing
            protocol, the VLSM can not be implemented.




Internet Protocol Address                                   27
               Classless Inter-Domain Routing

           CIDR removes the concept of Class A, Class B,
            Class C address.
           Every address simply contains network and host
            portions.
           CIDR supports route aggregation that a single
            route can represent the thousands of actual
            routes.
           All routers must advertise both the network
            address and the subnet mask.


Internet Protocol Address                                    28

				
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