IP addresing - is the method used to identify hosts and network devices
IP address
  • 32 bits
  • are usually displayed in dotted-decimal notation (eg. 192.168.1.106)
  • are hierarchical
Class D is reserved for multicasting and Class E is reserved for experimental use.
The class of the network is indicated by the values of the first few bits of the Ip addresses, called the high order bits.
  • Class A (1-126) – the first bit is 0
  • Class B (127-191) – the first 2 bits are 10.
  • Class C (192-223) – the first three bits are 110.
  • Class D (224-239) – the first four bits are 1110.
  • Class E(240-255) – the first five bits are 11110.
Private addresses – have no connection with public addresses
                                     – are not to be routed accross the Internet
                                     – Class A: 10.0.0.0 – 10.255.255.255   1 network
                                     – Class B: 17.16.0.0 – 17.31.255.255   16 networks
                                     – Class C: 192.168.0.0 – 192.168.255.255   256 networks
Fixed length subnetting – the same number of host bits is used to designate the subnet ID for all the resulting subnetworks. This type of subnetting always results in a fixed number of subnets and a fixed number of hosts per subnet. All subnets must be the same size.
To determine how many host bits to use for the subnet ID we have to know the number of hosts on each network and the number of individual local networks needed.
 Custom subnet mask – any subnet mask that is not a default class A, B or C subnet mask.
Subnetting
  • it permitted organizations that owned a class A,B or C address to subdivide their address space into smaller local subnets to more efficiently assign addresses
  • is also important to minimize traffic loads and for adding security measures between networks.
VLSM
  • Variable length subnet masking
  • allows an address space to be divided into networks of various sizes
  • this is done by subnetting subnets
  • router today must receive routing information that includes the IP address of the network and the subnet mask information
CIDR
  • Classless Inter Domain Routing
  • identifies networks based solely on the number of bits in the network prefix
  • eg. 172.16.1.1/16 where /16 represents the numbers of bits in the network prefix
  • more efficeint use IPv4 address space
  • prefix aggregation, which reduced the size of the routing tables.
NAT (Network address translation) – allows a large group of private users to access the Internet by sharing one or more public IP addresses
         – advantages:
  • public IP sharing
  • transparent to end users
  • improved security
  • LAN expandability
  • local control including ISP connectivity
        – disadvantages:
  • incompatibility with certain application
  • hinders legitimate remote access
  • performance reduction caused by increased router processing
  1. Inside local network – any network connected to a router interface that is part of the privately addresses LAN.
  2. Outside global network – any network attached to the router that is external to the LAN and doesn`t recognize the private addresses assigned to host on the LAN.
  3. Inside local address – private IP address configures on the host on an inside network
  4. Inside global address – IP address of an inside host as it appears to the outside network
  5. Outside local address – destination address of the packet while it is on the local network
  6. Outside global address – public IP address of an external host; the address is allocated from a globally routable address or network space
Dynamic NAT – allows hosts on a private network that have private Ip addresses to acces a public network, such as the Internet
Static translation
  • ensure that an individual host private IP addresses is always translated to the same registered global IP addresses
  • it ensures that no other local host is translated to the same registered global IP addresses
PAT
  • translates multiple local addresses to a single global IP address
  • PAT conversations use a single temporary IP address and port number combination
IPv6 - 128 bits
           – 32 hexadecimal digits
           – three party hierarchy : global prefix, subnet mask and interface ID