IP Addressing Pertemuan 18 Matakuliah: H0484/Jaringan Komputer Tahun: 2007

Bina Nusantara Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Menjelaskan IP Addressing

Bina Nusantara Outline Materi Classful Addressing Special Addresses Subnet mask

Bina Nusantara IP Address – A logical address used in TCP/IP networking for identifying a host in the network IP Address Characteristics – An IP address is 32 bits in size, unique, grouped into four 8-bit octets – Octets are separated by decimal points Network Administrator – IP addresses are assigned by a network administrator according to an organization’s valid IP address range. ICANN (Internet Corporation for Assigned Names & Numbers) – Central authority on Internet addresses and names. – A group of IP addresses must be obtained via an ISP. IP Address

Bina Nusantara IPv4 Address Formats

Bina Nusantara Classful Addresses

Bina Nusantara Network Addresses In classful addressing, the network address is the one that is assigned to the organization The network address defines the network to the rest of the Internet. Given the network address, we can find the class of the address, the block, and the range of the addresses in the block

Bina Nusantara Some IP address numbers are reserved for special functions. IP address whose numeric value is the highest value in the network (host bits all equal to one) is a broadcast address. IP addresses with first octet of 127 such as is a loopback IP used to test local workstation communication IP addresses ending in “1” are typically reserved for gateway Special IP Addresses

Bina Nusantara Private Addresses A number of blocks in each class are assigned for private use. They are not recognized globally Several techniques exist to hide internal network IP addresses from outside view Within the Class A, B, and C IP address ranges, the IETF has reserved private IP addresses or address ranges Any organization can use these addresses provide they adhere to the rules All connectivity to an Internet host must be provided by a Network Address Translator

Bina Nusantara Rules: They cannot be referenced by hosts in another organization They cannot be defined to any external router Organization with private addresses cannot externally advertise those IP Addresses and cannot forward IP datagrams containing those addresses to external routers External routers will quietly discard all routing information regarding these addresses Private IP Addresses

Bina Nusantara Private IP addresses relax the rule that IP addresses are globally unique This IP conservation technique reserves part of the IP address space for use exclusively within an organization The organization does not require connectivity to the Internet Private IP Addresses

Bina Nusantara IANA reserves three ranges of IP addresses for "Private Internets": A single Class A network Sixteen continuous Class B Networks contiguous Class C networks Private IP Addresses

Bina Nusantara Subnetting Allows the use one class of addresses for several network segments A subnetted address is comprised of three parts  Network address  Subnet address  Host address Subnet address uses part of the host address for subnet address assignment Efficient use of IP addresses

Bina Nusantara A subnet mask is a special bit pattern that blocks off the network portion of an IP address with an all-ones pattern The entire network address, including the network prefix and the subnetting bits, is called the extended network prefix This activity of stealing bits from the host portion of further subdivide the network portion of an address is called subnetting a network address, or subnetting Subnetting

Bina Nusantara A subnet mask that is larger than the default mask for the address in use divides a single network IP address into multiple subnetworks The network prefix identifies the number of bits in the IP address, counting from the left that represents the actual network address itself, and the additional bits of subnetting represent the bits that were borrowed from the host portion of that IP address to extend the network portion When a computer on one subnet wishes to communicate with a computer on another subnet, traffic must be forwarded from the sender to a nearby IP gateway to send the message on its way from one subnet to another Subnetting

Bina Nusantara Subnetting Subnet mask composed of four octets and can be expressed in either binary or dotted decimal notation – Octet of all 1’s Represents part of the extended network prefix that uses that subnet mask. – Octet of all 0’s Represents corresponding octets that are assumed to represent host information. – Binary Notation – Dotted Decimal Notation

Bina Nusantara Default mask and subnet mask

Bina Nusantara Subnetting  First 2 octets represent part of extended network prefix.  3rd octet represents subnet.  4th octet represents host/machine/device.  Router needed to interpret addresses.  IP ending in “1” always reserved for gateways address.