Transcript MCL-H0484 - Binus Repository

Matakuliah : H0524/Jaringan Komputer
Tahun
: 2009
IP Addressing
Pertemuan 06
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Membagi IP Address
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Outline Materi
• Classful Addressing
• Special Addresses
• Subnet mask
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IP Address
• 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.
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IPv4 Address Formats
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Classful Addresses
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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
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Special IP Addresses
• 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
127.0.0.1 is a loopback IP used to test local
workstation communication
• IP addresses ending in “1” are typically
reserved for gateway.
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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
• 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
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Private IP Addresses
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.
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Private IP Addresses
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.
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Private IP Addresses
Reserved IANA IP addresses for Private Internets
• 10.0.0.0 - 10.255.255.255
A single Class A network
• 172.16.0.0 - 172.31.255.255
Sixteen continuous Class B Networks
• 192.168.0.0 - 192.168.255.255
256 contiguous Class C networks
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Subnetting
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
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Subnetting
• 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
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Subnetting
• 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
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Subnetting
• 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.
• Subnet mask composed of four octets and
can be expressed in either binary or dotted
decimal notation.
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Subnetting
•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
11111111.11111111.1111111.00000000
•Dotted Decimal Notation
255.255.255.0
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Default mask and subnet mask
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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.
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