Chapter%20Overview

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Chapter Overview

• IP (v4) Address
• IPv6

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IPv4 Addresses

• Internet Protocol (IP) is the only network layer
  protocol with its own addressing system and is
  design for a host on one network to communicate
  with another host on a different network,
  regardless the type of LAN
• IP addresses are 32 bits long and have two parts
  a network identifier and a host identifier.
• IP addresses are assigned to network interface
  adapters, not to computers.
• The Source IP Address field in the IP header
  always identifies the computer that generated the
  packet.
• The Destination IP Address field in the IP header
  always identifies the packets final destination.

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ipconfig
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IP Address Assignments

• Every network interface adapter on a network must
  have
• The same network identifier as the others on the
  network
• A unique host identifier
• The Internet Assigned Numbers Authority (IANA)
  assigns network identifiers, but you typically
  obtain network addresses from an Internet service
  provider (ISP).
• Network administrators, or DHCP, assign host
  identifiers.

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• Dotted decimal
• For example,
• 124.241.144.2
• This is not one
• 1.1.1.256
• The binary and hexadecimal are not common to say
  the least

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IP Address Classes
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IP Address Class First Bit/Byte Values
Class First Bits First Byte Values
A 0 1127
B 10 128191
C 110 192223
Class D (224-239) and E (240-255)
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IP Address Class Network and Host Bits
Class Network ID Bits Host ID Bits Number of Networks Number of Hosts
A 8 24 126 16,777,214
B 16 16 16,384 65,534
C 24 8 2,097,152 254
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Private Network Addresses
Class Network Addresses
A 10.0.0.0 through 10.255.255.255
B 172.16.0.0 through 172.31.255.255
C 192.168.0.0 through 192.168.255.255
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IP Addressing Rules

• All the bits in the network identifier cannot be
  set to zeros.
• All the bits in the network identifier cannot be
  set to ones.
• All the bits in the host identifier cannot be set
  to zeros.
• All the bits in the host identifier cannot be set
  to ones.

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Reserved IP addresses
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Automatic Private Internet Protocol Addressing
(APIPA)

• a common alternative to the use of DHCP to
  request and retrieve an IP address for a host.
• simplifies the assignment of IP address and
  subnet-mask configuration information to hosts in
  small networks.
• When APIPA is used, the OS allows the assignment
  of a unique IP address to each station on a small
  LAN to avoids the administrative overhead of
  running a DHCP server or manually setting IP
  configuration information.

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Different types of broadcasts

• Layer 2 broadcast -- all nodes on a LAN
• Broadcast (Layer 3) to all hosts on the network
• Unicast a node sends a message to
  255.255.255.255 with port number 67 (BootP
  server), router knows it is for DHCP asking for
  an IP address, so forward to DHCP server
• Multicast one host to several hosts, forwarded
  by router

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IPv6 Addressing

• Expands IP address space from 32 to 128 bits
• Designed to prevent the depletion of IP addresses
  and address-exhaustion crisis of IPv4, later
  modified to add features for flexibility,
  efficiency, capability, mobility, etc
• Uses XXXXXXXXXXXXXXXX notation, each X is
  a pair of hexadecimals

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IPv6 Addressing (2)

• Global routing prefix used by router for the
  network
• A subset of a network
• A host address

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IPv6 Addressing (3)

• You can only replace one contiguous block of
  zeros in an address

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IPv6 Address Types

• Unicast very much the same as IPv4 unicast
• Global unicast unicast, start with 001
• Link-local address -- private, not to be routed
  (FE80 addresses) for point to point, not
  forwarded
• Unique local address -- FC00/
• Multicast to all
• Anycast -- to one

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Special address

• 00000000 same as 0.0.0.0 in IPv4 not
  for communication
• 00000001 1 same as 127.0.0.1 for
  loopback
• 000000192.168.100.1 mixing IPv4 with IPv6
• 200/3 global unicast address range
• FC00/7 unique local unicast range
• EF80/10 link-local unicast range
• FF00/8 The multicast range
• 3FFFFFFF/32 and 20010DB8/32 for examples
  and document
• 2002/16 for 6 to 4

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2002/16 for 6 to 4

• For any 32-bit global IPv4 address, a 48-bit 6to4
  IPv6 prefix can be constructed for use by that
  host (and if applicable the network behind it) by
  prepending 2002 (hex) to the IPv4 address.
• For example, for192.0.2.42, the corresponding
  6to4 prefix would be 2002c000022a/48.
• This gives a prefix length of 48 bits, which
  leaves room for a 16-bit subnet field and a 64
  bit host address within the subnet.