IPv6 Addressing • Designed to increase the size of the IP address space (128 bit), thus providing addresses for many more devices than IPv4 • Reduces the size of the routing tables because the size of the addresses provides for more than the two levels of subnetting currently possible with IPv4 IPv6 Addressing 128-bit identifiers for interfaces Three types of addresses Unicast Anycast Multicast 2018 Large Adresse Space IPv4 ~ = bits or 4 bytes long • 32 • 4,200,000,000 possible addressable nodes IPv6 ~ • 128 = bits or 16 bytes: four times the bits of IPv4 ~ • 3.4 * 1038 possible addressable nodes = ~ = • 340,282,366,920,938,463,374,607,432,768,211,456 • 5 * 1028 addresses per person Simple and Efficient Header A simpler and more efficient header means: • Hardware-based, efficient processing • Improved routing efficiency and performance • Faster forwarding rate with better scalability benefits IPv6 are : Increased address space Simplified configuration (with auto configuration) Integrated security (IPSec) Backward compatibility with IPv4 Version Traffic Class Pay Load Length Flow Label Next Header Hop Limit 40 Octet Source Address Destination address Data Varia le Leng Source address: It is of 128 bits and contains the IPv6 address of the originating node of the packet. Destination address: It is of 128 bits and contains the IPv6 address of the recipient node of the packet. Version/IP version: It is of 4 bits and contains the number 6.It indicates the version of the IPv6 protocol. Time To Live (TTL)/Hop Limit (8 bits): The 8-bit Hop Limit field is decremented by one, by each node (typically a router) that forwards a packet. If the Hop Limit field is decremented to zero, the packet is discarded Unicast : Provides one-to-one transmission service to individual interfaces, Identifier for a single interface. Packet sent to a unicast address delivered to interface identified by that address. Anycast : Provides one-to-one-of-many transmission service to groups of interfaces, Identifier for a set of interfaces. Packet sent to an address of this type is delivered to one of the interfaces identified by the address (nearest one). Multicast : Provides one-to-many transmission service to groups of interfaces identified by a single multicast address. Identifier for a set of interfaces…a packet sent to an address of this type is delivered to all interfaces identified by that address. There are three conventional forms for representing IPv6 addresses as text strings. x:x:x:x:x:x:x:x 'x's are the hexadecimal values of the eight 16-bit pieces of the address. FEDC:BA98:7654:3210:FEDC:BA98:7654:3210 1080:0:0:0:8:800:200C:417A A special syntax for compressing long strings of zero bits will be used. "::" indicates multiple groups of 16-bits of zeros. Can only be used once. • Basic IPv6 Address Format Global Unicast Addresses The current official format for global unicast addresses consists of the following elements: • Unicast Address : A 48-bit field beginning with the 001 in binary, • Subnet ID: a 16-bit field that organizations can use to create an internal hierarchy of sites or subnets • Interface ID: A 64-bit field identifying a specific interface on the network 13 Expressing IPv6 Network Addresses • No subnet masks in IPv6 • Network addresses use the same slash notation as CIDR: 21cd:53::/64 • This is the contracted form for the following network address: 21cd:0053:0000:0000/64 14 IPv6 Addressing Types Unicast Address 1. Link local address 2. Site local address 3. Global address 1.Link local address – Used on a single link – Prefix is 1111 1110 10 – FE80: | 10 bits | 54 bits | 64 bits | +--------------- +-------------------------+----------------------------+ |1111111010 | 0 | interface ID | +----------------+-------------------------+----------------------------+ IPv6 Addressing 2. Site local address – Used on a single site – Prefix is 1111 1110 11 – FEC0: | 10 bits | 38 bits | 16 bits | 64 bits | +----------------+-------------+-------------+--------------------------+ |1111111011| 0 | subnet ID | interface ID | +----------------+----------+-----------------+-------------------------+ IPv6 Addressing • Global address – Unique in Internet – Prefix is 001 | 3| 13 | 8 | 24 | 16 | 64 bits +--+-----+---+-------+---------------+-----------------------------+ |FP| TLA |RES| NLA | SLA | Interface ID | | ID | | ID | ID | +--+-----+---+--------+---------------+----------------------------+ | | | IPv6 Addressing 2. Anycast address When a unicast address is assigned to more than one interface, thus turning it into an anycast address, | 10 bits | 38 bits | 16 bits | 64 bits | +----------------+-------------+-------------+--------------------------+ |1111111011| 0 | subnet ID | interface ID | +----------------+----------+-----------------+-------------------------+ IPv6 Addressing • Multicast Addresses Is an identifier for a group of nodes. | 8 | 4| 4 | 112 bits | +------------------+----+--------+---------------------------------------------+ |*11111111 |flgs|scop| ** group ID | +------------------+----+---------+---------------------------------------------+ • • • • • • • • *11111111identifies the address as a multicast address **Group ID identifies the multicast group (permanent or transient) flgs is a set of 4 flags: |0|0|0|T| The high-order 3 flags are reserved, and must be initialized to 0. T = 0 indicates a permanently-assigned ("well-known") multicast address, assigned by the global internet numbering authority. T = 1 indicates a non-permanently-assigned ("transient") multicast address. scop is a 4-bit multicast scope value used to limit the scope of the multicast group. Examples of addresses Uncompressed 1080:0:0:0:8:800:200C:417A Compressed 1080::8:800:200C:417A . Examples of Addresses Uncompressed FF01:0:0:0:0:0:0:101 Compressed FF01::101 . Examples of Loopback Addressing Uncompressed 0:0:0:0:0:0:0:1 Compressed ::1 Examples of unspecified addressing Uncompressed 0:0:0:0:0:0:0:0 Compressed ::
