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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 packet’s final destination.

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.

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 1–127

B 10 128–191

C 110 192–223

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.

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 XX:XX:XX:XX:XX:XX:XX:XX notation, each X is a pair of hexadecimals

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 0:0:0:0:0:0:0:0 == :: same as 0.0.0.0 in IPv4 not for

communication 0:0:0:0:0:0:0:1 == ::1 same as 127.0.0.1 for loopback 0:0:0:0:0:0:192.168.100.1 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 3FFF:FFFF::/32 and 2001:0DB8::/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 2002:c000:022a::/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.

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