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04 IP Addressing Scheme

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04 IP Addressing Scheme Powered By Docstoc
					       IP Addressing Scheme
             (Topic 4)
                       Textbook:
Networking Basics, CCNA 1 Companion Guide, Cisco Press
Cisco Networking Academy Program, CCNA 1 and 2,
Companion Guide, Cisco Press, Latest Edition




                 CIM 2465 IP Addressing Scheme           1
    IP Address Fundamentals
• Logical address
• IPv4 (32 bits, usually in dotted-decimal,
  e.g. 192.168.123.1)
• Must be unique inside a particular network




               CIM 2465 IP Addressing Scheme   2
      Address Assignment (1)
• All hosts on the same LAN must use the same
  value for the first part of their IP addresses
  (length depends on size of the network)
• IP addresses are assigned to network interfaces
  rather than to entire computers




                CIM 2465 IP Addressing Scheme       3
     Address Assignment (2)
• ipconfig




             CIM 2465 IP Addressing Scheme   4
     Address Assignment (3)
• 3 key rules
  – Devices on the same LAN must use IP
    addresses in the same group (IP network)
  – Devices on different LANs that are separated
    by at least one router must use IP addresses
    in different IP networks
  – IP addresses must be unique inside the same
    internetwork
• Fig 9-13
                CIM 2465 IP Addressing Scheme      5
• Three networks
  – All IP addresses that begin with 10
  – All IP addresses that begin with 11
  – All IP addresses that begin with 12
                   CIM 2465 IP Addressing Scheme   6
             Network Classes (1)
• Unicast IP address
   – An IP address that can be assigned to a single interface
• IPv4 defines 3 three classes of unicast IP addresses, determined
  by the value of the first octet of the address
• An address includes two parts (no subnetting)
   – network part
   – host part

Range of values          Class         Length of          Length of Host
In first octet                         Network Part       Part
1-126                      A           1 octet            3 octets

128-191                    B           2 octets           2 octets


192-223                    C           3 octets           1 octet
                         CIM 2465 IP Addressing Scheme                     7
             Network Classes (2)
• Fig 9-14




• A unicast IP address determines its class and structure,
  specifically, the size of the network and host parts of the
  address
• An IP network consists of all unicast IP addresses for
  which the network part’s value is the same
                     CIM 2465 IP Addressing Scheme              8
             Network Classes (3)
• Fig 9-15




IP Address      Class      Network part          Host part
10.1.1.1
172.22.3.4
192.168.55.66
                 CIM 2465 IP Addressing Scheme               9
           Network Classes (4)
• IPv4 uses class D IP addresses to multicast packets to a
  multicast destination IP address (all hosts will receive a
  copy of the packet)
• Table 9-7




• Values of 0 and 127 are not listed in the first octet
   – 127.0.0.1, loopback IP address
   – Network 0.0.0.0 has been reserved
                     CIM 2465 IP Addressing Scheme         10
             Network Classes (5)
• IP network number (network ID) is a dotted-decimal number that
  represents a particular IP network. E.g. 10.0.0.0
• First and last number in a network are reserved
   – 10.0.0.0 (network ID)
   – 10.255.255.255 (network broadcast address)


IP Address         Class      Network address Host address
10.1.1.1
172.22.3.4
192.168.55.66


                       CIM 2465 IP Addressing Scheme               11
        Network Classes (6)
• Fig 9-17




             CIM 2465 IP Addressing Scheme   12
  Number of Hosts per Network
• Depends on number of bits of the Host part


Class   Network Host            Number of Hosts per
        part (bits) part (bits) Network
A
B
C


                CIM 2465 IP Addressing Scheme    13
    Number of Class A, B, C Networks
• Depends on number of bits of the network part
• How many class A? 28 ? 28 – 2 ?


Class Network “Fixed” bits Bits that Number of Networks
      part (bits) at beginning can vary
A

B

C


                     CIM 2465 IP Addressing Scheme        14
             Subnetting (1)
• Subnetting allows the network designer to
  subdivide a classful IP network into
  smaller groups, called subnets
• Class A network 10.0.0.0, was divided into
  three subnets
  – 10.1.1
  – 10.1.2
  – 10.1.3

               CIM 2465 IP Addressing Scheme   15
               Subnetting (2)
• Key rules
  – Devices on the same LAN must use IP addresses in
    the same group (IP subnet)
  – Devices on different LANs that are separated by at
    least one router must use IP addresses in different IP
    subnet
  – IP addresses must be unique inside the same
    internetwork
• Subnet: A group of IP addresses that all have
  the same value in the first part of the address
• Subnet number: A dotted-decimal number that
  represents a particular IP subnet

                   CIM 2465 IP Addressing Scheme         16
• Three subnets
  – IP addresses beginning with 10.1.1
  – IP addresses beginning with 10.1.2
  – IP addresses beginning with 10.1.3




                   CIM 2465 IP Addressing Scheme   17
   Various Views of Subnetted IP
            Addresses
• Fig 9-19




             CIM 2465 IP Addressing Scheme   18
                           Subnet Mask
  • To find out the network (and subnet) parts of an IP
    address, thus determine whether two hosts are in the
    same network
  • To determine if the network is subnetted
IP Address     Mask                Class Network             Subnet   Host
10.1.2.3       255.0.0.0
172.22.109.4   255.255.0.0
192.168.1.109 255.255.255.0
10.1.2.3       255.255.0.0
172.22.109.4   255.255.224.0
192.168.1.109 255.255.255.224


                             CIM 2465 IP Addressing Scheme                   19
   Ensuring Unique IP Addresses
      Throughout the Internet
• Unique IP addresses on all computers?
• Unique Network Address for Each
  Enterprise Network
• Internet Assigned Numbers Authority
  (IANA), IANA member organizations
• IPv4 Address Depletion
  – NAT, Private IP Networks
  – IPv6 (128 bits)
               CIM 2465 IP Addressing Scheme   20
• Fig 9-20




             CIM 2465 IP Addressing Scheme   21
NAT and Private IP Networks (1)
• NAT allows a company to use just a few registered IP addresses
  instead of an entire registered Class A, B, or C networks
• Fig 9-21




                       CIM 2465 IP Addressing Scheme               22
NAT and Private IP Networks (2)
Class Range of Network                           Total Number
      Numbers                                    of Networks
  A   10.0.0.0                                         1


  B   172.16.0.0 – 172.31.0.0                         16


  C   192.168.0.0 –                                  256
      192.168.255.0
                 CIM 2465 IP Addressing Scheme                  23
IPv4 Vs IPv6




 CIM 2465 IP Addressing Scheme   24
     Assigning and Mapping IP
             Addresses
• A planning process
• Two popular methods
  – Static IP Address Configuration
  – Dynamic configuration using (DHCP)




               CIM 2465 IP Addressing Scheme   25
Static IP Address Configuration
• Fixed IP addresses entered by users
• Key Config Options
   – IP address, Subnet mask, Default gateway, DNS server
• Fig 9-23




                     CIM 2465 IP Addressing Scheme          26
CIM 2465 IP Addressing Scheme   27
Dynamic IP Config Using DHCP
• Dynamic Host Configuration Protocol (DHCP)
• DHCP allows a host that does not have a static
  IP address configured on an interface to send a
  request to a DHCP server
• The server then sends back a DHCP reply (IP
  address that can be used, mask, default
  gateway, and DNS server, and other control
  information)


                 CIM 2465 IP Addressing Scheme      28
• Fig 9-25




             CIM 2465 IP Addressing Scheme   29
         DHCP Mechanism
• Fig 9-26




             CIM 2465 IP Addressing Scheme   30
   Advantages of using DHCP
• When companies move employees and their
  PCs, the PCs can be installed in the new offices,
  send a DHCP request, and be up and running
• Laptop computers can be moved all over a
  network (company, home, hotel…)
• DHCP server can keep statistics of the usage of
  IP addresses
• DHCP reclaims the IP address once the lease
  expires so another host can use the IP
  addresses

                 CIM 2465 IP Addressing Scheme    31
          Why use Static IP
• Server IP addresses need to stay the
  same
• Routers, switches need to stay at the
  same IP addresses
• End-user hosts do not move often
• Network administration



               CIM 2465 IP Addressing Scheme   32
              Using ARP
• For an IP host to send an IP packet over a
  LAN, the sending host must know the
  Ethernet MAC address of another device
  on the LAN
• By Address Resolution Protocol (ARP)




               CIM 2465 IP Addressing Scheme   33
CIM 2465 IP Addressing Scheme   34
ARP Process




 CIM 2465 IP Addressing Scheme   35
Using IP ARP in Larger Network




          CIM 2465 IP Addressing Scheme   36
CIM 2465 IP Addressing Scheme   37

				
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