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IPv6 Addressing

IPv6 Addressing. IPv6 Addressing Model. No real change from the IPv4 model. Addresses assigned to interfaces. – Interfaces can have multiple addresses. IPv6 addresses can be classified into one of three categories:. Note. An IPv6 address is 128 bits long. IPv6 Addressing Syntax.

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IPv6 Addressing

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  1. IPv6 Addressing

  2. IPv6 Addressing Model • No real change from the IPv4 model. • Addresses assigned to interfaces. – Interfaces can have multiple addresses. • IPv6 addresses can be classified into one of three categories:

  3. Note An IPv6 address is 128 bits long.

  4. IPv6 Addressing Syntax • IPv6 address are assigned to interfaces, not nodes. – A node can be identified by any of the address of any of its interfaces. • A single interface can be assigned multiple IPv6 addresses of any type (unicast, multicast, anycast). Further information is specified in RFC2373. • A typical IPv6 address consists of three parts, the global routing prefix, the subnet ID, and the interface ID: Used to identify special address or address range to a site. Used to identify a link Within a state. Used to identify an interface on a link. Needs to be unique on that link. Usually the EUI-64 format of the NIC.

  5. IPv6 Addressing Notation • IPv6 address have 128-bits, or 16 bytes which is divided into eight 16-bit hexadecimal blocks separated by colons: – 2001:c18:b401:1:201:2ff:fe8a:d62b • Abbreviations to this address are possible. – Leading zeros in a 16-bit block can be skipped and replace by a ‘::’. – FE80:0000:0000:0000:0203:B3FF:FE1E:8329 can be abbreviated to: • FE80::0203:B3FF:FE1E:8329 • A double colon can replace consecutive zeros, leading zeros, or trailing zeros within an address and can only be used once. – A host always uses a 128-bit representation of the address even when it is simplified and expands it with as many zeros as are needed to get a 128-bit address. – 2001:0C18:0000:0056:0000:ABCD:EF12:1234 can be abbreviated as: • 2001:0C18::0056:0000:ABCD:EF12:1234 • 2001:0C18:0000:0056::ABCD:EF12:1234 and not as 2001:0C18::0056::ABCD:EF12:1234

  6. IPv6 address in binary and hexadecimal colon notation

  7. Abbreviated IPv6 addresses

  8. Example Expand the address 0:15::1:12:1213 to its original. Solution We first need to align the left side of the double colon to the left of the original pattern and the right side of the double colon to the right of the original pattern to find how many 0s we need to replace the double colon. This means that the original address is.

  9. Type prefixes for IPv6 addresses

  10. Type prefixes for IPv6 addresses (continued)

  11. Prefixes for provider-based unicast address

  12. Unicast Addresses • Type identifier: 3-bit defines the address as a provider-based. • Registry identifier: 5-bit indicates the agency that has registered the address. • Provider identifier: variable length (16-bit recommended) identifies the provider for Internet access. • Subscriber identifier: variable length (24-bit recommended) assigned to organization from provider when organization subscribe to Internet. • Subnet identifier: variable length (32-bit recommended) defines specific subnetwork under the territory of the subscriber. • Node identifier: 48-bit defines the identity of a node connected (usually it is the physical address used by Ethernet).

  13. Multicast address in IPv6

  14. Reserved addresses in IPv6

  15. Link-Local and Site-Local Addresses • Similar to RFC1918 private IP address in IPv4. • IPv6 allocates two separate addresses for link- and site-local use. – A link-local address is for use on a single link and should never be routed. Uniquely identified by the format prefix FE80::/10. • Used for autoconfiguration mechanisms, neighbor discovery, and on networks with no routers. – A site-local address contains subnet information within the address. Can be routed within a site, but routers do not route packets with site-local addresses outside of the site. Uniquely identified by the format prefix FEC0::/10. – Both address types can be used without a global prefix.

  16. Local addresses in IPv6

  17. Router Advertisement • Router advertisement (RA) messages are sent out periodically. – RA message contains link prefix, lifetime, MTU, etc information. • Hosts construct address by appending respective EUI-64 identifier (which is created from the 48-bit interface MAC address) - Appendix A of RFC 2373. • Hosts can also request RA by issuing a Router Solicitation message. This triggers routers to issue RAs outside of the regular interval. • This address then needs to be tested to ensure uniqueness via Duplicate Address Detection (DAD). • Auto configuration steps: 1. Link-local address is created by using link-local prefix (FE80::/10). This is a tentative address. 2. The host joins the ‘all-nodes’ (FE02::1) and the ‘solicited-node’ multicast groups. 3. A Neighbor Solicitation message is sent out with target set with tentative address as in (1). Source is all-zeros; destination is solicit-node multicast address. DAD step. Auto configuration step stops if a Neighbor Advertisement message is received. Otherwise IP connectivity via local-link address is established. 4. To determine routers available a Router Solicitation message (FF02::02) is sent. 5. All routers on the link will respond with RA message. An address is generated combining prefix and EUI-64.

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