IPv6 are 128-bit identifiers (addresses) for interfaces and sets of interfaces. IPv6 addresses are assigned to interfaces, not nodes. There are three types of addresses-
1. Unicast: An identifier for a single interface. A packet sent to unicast address is delivered to a single interface identified by that address.
2. Anycast: An identifier for a set of interfaces. A packet sent to an anycast address is delivered to one of the interfaces identified by that address- the "closest" interface as suggested by the routing protocol.
3. Multicast: An identifier for a set of interfaces. A packet sent to a multicast address is delivered to all of the interfaces identified by that address.
IPv6 addresses are notified in the form X:X:X:X:X:X:X:X where "X" is a hexadecimal value with eight 16-bit pieces- each piece is represented by four hexadecimal digits seperated by a colon.
For example- a typical IPv6 address may look like FEDC: 0001: 0000: 0000: 0000: 0000: ABDC: 0FF0.
Since an IPv6 address may contain a long string of zero bits, few rules have been developed to write these addresses with ease.
Rule 1: The use of "::" indicates multiple groups of 16-bits of zeroes.
Rule 2: The "::" can appear only ONCE in an address.
Rule 3: The "::" can also be used to compress leading or trailing zeroes in an address.
For example- the IPv6 address FEDC: 0001: 0000: 0000: 0000: 0000: ABDC: 0FF0 can be compressed to FEDC: 1:: ABDC: FF0.
Also, the IPv6 address FEDC: 0000: 0000: 0001: 0000: 0000: ABDC: 0FF0 can be compressed to FEDC :: 1: 0: 0: ABDC: FF0. The "::" cannot appear twice in an address.
And, IPv6 address 0000: 0000: 0000: 0000: 0001: FEDC: ABDC: 0FF0 can be compressed to :: 1: FEDC: ABDC: FF0.
Rule 4: When dealing with a mixed IPv4 and IPv6 environment, the X:X:X:X:X:X.d.d.d.d is used where "X" are hexadecimal values of six high-order 16-bit pieces of the address, and "d" are the decimal values of four low-order 8-bit pieces of the address (the actual 32-bit IPv4 address).
For example- 0:0:0:0:0:0:10.1.8.24 or in compressed form ::10.1.8.24
IPv6 address prefixes can be written in a manner similar to CIDR notation ipv6-address/ prefix-length where
ipv6 address is an IPv6 address
prefix-length is a decimal value specifying how many leftmost contiguous bits of the address comprise the prefix.
For example- the following are legal representations of 60-bit prefix 1234: 0000: 0000: 0CB3.
1234: 0000: 0000: CB3: 0000: 0000: 0000: 0000/60
1234: 0: 0: CB3::/60
1234::CB3: 0: 0: 0: 0/60
However, 1234::CB3/60 is illegal since it means 1234: 0: 0: 0: 0: 0: 0: CB3/60.
1. Unicast: An identifier for a single interface. A packet sent to unicast address is delivered to a single interface identified by that address.
2. Anycast: An identifier for a set of interfaces. A packet sent to an anycast address is delivered to one of the interfaces identified by that address- the "closest" interface as suggested by the routing protocol.
3. Multicast: An identifier for a set of interfaces. A packet sent to a multicast address is delivered to all of the interfaces identified by that address.
IPv6 addresses are notified in the form X:X:X:X:X:X:X:X where "X" is a hexadecimal value with eight 16-bit pieces- each piece is represented by four hexadecimal digits seperated by a colon.
For example- a typical IPv6 address may look like FEDC: 0001: 0000: 0000: 0000: 0000: ABDC: 0FF0.
Since an IPv6 address may contain a long string of zero bits, few rules have been developed to write these addresses with ease.
Rule 1: The use of "::" indicates multiple groups of 16-bits of zeroes.
Rule 2: The "::" can appear only ONCE in an address.
Rule 3: The "::" can also be used to compress leading or trailing zeroes in an address.
For example- the IPv6 address FEDC: 0001: 0000: 0000: 0000: 0000: ABDC: 0FF0 can be compressed to FEDC: 1:: ABDC: FF0.
Also, the IPv6 address FEDC: 0000: 0000: 0001: 0000: 0000: ABDC: 0FF0 can be compressed to FEDC :: 1: 0: 0: ABDC: FF0. The "::" cannot appear twice in an address.
And, IPv6 address 0000: 0000: 0000: 0000: 0001: FEDC: ABDC: 0FF0 can be compressed to :: 1: FEDC: ABDC: FF0.
Rule 4: When dealing with a mixed IPv4 and IPv6 environment, the X:X:X:X:X:X.d.d.d.d is used where "X" are hexadecimal values of six high-order 16-bit pieces of the address, and "d" are the decimal values of four low-order 8-bit pieces of the address (the actual 32-bit IPv4 address).
For example- 0:0:0:0:0:0:10.1.8.24 or in compressed form ::10.1.8.24
IPv6 address prefixes can be written in a manner similar to CIDR notation ipv6-address/ prefix-length where
ipv6 address is an IPv6 address
prefix-length is a decimal value specifying how many leftmost contiguous bits of the address comprise the prefix.
For example- the following are legal representations of 60-bit prefix 1234: 0000: 0000: 0CB3.
1234: 0000: 0000: CB3: 0000: 0000: 0000: 0000/60
1234: 0: 0: CB3::/60
1234::CB3: 0: 0: 0: 0/60
However, 1234::CB3/60 is illegal since it means 1234: 0: 0: 0: 0: 0: 0: CB3/60.
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