IP Version 6 Addressing Architecture RFC 2373 Presented by Vickie Brown

IPv6 Addressing 128-bit identifiers for interfaces Three types of addresses Unicast Anycast Multicast

IPv6 Addressing Unicast  Identifier for a single interface. Packet sent to a unicast address delivered to interface identified by that address.

IPv6 Addressing Anycast  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).

IPv6 Addressing Multicast  Identifier for a set of interfaces…a packet sent to an address of this type is delivered to all interfaces identified by that address.

Unlike IPv4, there are no broadcast addresses in IPv6…multicast addresses are utilized in place of broadcast addresses. All zeros and all ones are legal values for any field unless specifically excluded.  Prefixes may contain zero-valued fields or end in zeros. IPv6 Addressing

All types of IPv6 addresses are assigned to interfaces not nodes.  All interfaces are required to have at least one link-local unicast address.  A single interface may also be assigned multiple IPv6 addresses of any type.

IPv6 Addressing 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

IPv6 Addressing 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.  Can be used to compress leading or trailing zeros.

IPv6 Addressing Examples of Unicast addresses Uncompressed  1080:0:0:0:8:800:200C:417A Compressed  1080::8:800:200C:417A

IPv6 Addressing Examples of Multicast Addresses Uncompressed  FF01:0:0:0:0:0:0:101 Compressed  FF01::101

IPv6 Addressing Examples of Loopback Addressing Uncompressed  0:0:0:0:0:0:0:1 Compressed  ::1

IPv6 Addressing Examples of unspecified addressing Uncompressed  0:0:0:0:0:0:0:0 Compressed  ::

IPv6 Addressing Alternative form for dealing with mixed environments of IPv4 and IPv6 nodes. x:x:x:x:x:x:d.d.d.d  'x's are the hexadecimal values of the six high-order 16-bit pieces of the address.  'd's are the decimal values of the four low-order 8-bit pieces of the address.  Examples  0:0:0:0:0:0: (uncompressed)  :: (compressed)  0:0:0:0:0:FFFF: (uncompressed)  ::FFFF: (compressed)

IPv6 Addressing Text Representation of Address Prefixes Similar to IPv4 in CIDR (Classless Interdomain Routing). IPv6-address/prefix length Legal representations of 60-bit prefix 12AB CD3  12AB:0000:0000:CD30:0000:0000:0000:0000/60  12AB::CD30:0:0:0:0/60  12AB:0:0:CD30::/60  Node address and prefix for that node address can be combined.  12AB:0:0:CD30:123:4567:89AB:CDEF/60

IPv6 Addressing Specific type of IPv6 address is indicated by the leading bits in the address. Variable-length field is called the Format Prefix (FP).

IPv6 Addressing Initial allocation of prefixes Allocation Prefix Fraction of (binary) Address Space Reserved /256 Unassigned /256 Reserved for NSAP Allocation /128 Reserved for IPX Allocation /128 Unassigned /128 Unassigned /32 Unassigned /16

IPv6 Addressing Allocation continued… Aggregatable Global Unicast Addresses 001 1/8 Unassigned 010 1/8 Unassigned 011 1/8 Unassigned 100 1/8 Unassigned 101 1/8 Unassigned 110 1/8 Unassigned /16 Unassigned /32 Unassigned /64 Unassigned /128 Unassigned /512

IPv6 Addressing Allocation continued… Link-Local Unicast Addresses /1024 Site-Local Unicast Addresses /1024 Multicast Addresses /256

IPv6 Addressing Unspecified addresses, loopback addresses, and IPv6 with Embedded IPv4 Addresses are assigned out of the FP space. FPs 001~111 (except for Multicast Addresses ) are required to have 64-bit interface identifiers in EUI-64 format.

IPv6 Addressing Allocation supports the direct allocation of aggregation addresses and multicast addresses. 15% of the address space is initially allocated. 85% is reserved for future use.

IPv6 Addressing Unicast addresses can be differentiated from multicast addresses by the value of the high-order octet of the address. Example A value of FF( ) is a multicast address, any other value is a unicast address.  Anycast addresses are take from unicast address space and are not syntactically different.

IPv6 Addressing Unicast Addresses IPv6 unicast addresses are similar to IPv4. There are several forms of unicast address assignment in IPv6. Global aggregatable global unicast address NSAP address IPX address Site-local address Link-local address IPv4-capable host address

IPv6 Addressing Interface identifiers in IPv6 unicast addresses are used to identify interfaces on a link. Required to be unique on that link. Can be the same as link-layer address. Several FPs Interface IDs are required to be 64- bits long and constructed in IEEE EUI-64 format.

IPv6 Addressing Unspecified address consists of 0:0:0:0:0:0:0:0. It can never be assigned to any node. It is indicative of the absence of an address. It is used in the Source Address field of any IPv6 packets sent by an initializing host before it has learned its own address. Cannot be used as destination address in either IPv6 packets or IPv6 Routing Headers.

IPv6 Addressing The loopback address is used by a node to send an IPv6 packet to itself. The unicast address is 0:0:0:0:0:0:0:1 It cannot be assigned to any physical interface. It is more like a virtual interface.

IPv6 Addressing IPv6 Addresses with Embedded IPv4 Addresses. The Transition mechanism has a technique for host and routers to tunnel IPv6 packets over IPv4 routing infrastructures. Have a special unicast address that has IPv4 address in low-order 32-bits.

IPv6 Addressing IPv6 Addresses with Embedded IPv4 Addresses Continued… IPv4-compatable IPv6 Address | 80 bits | 16 | 32 bits | | |0000| IPv4 address |

IPv6 Addressing IPv6 Addresses with Embedded IPv4 Addresses Continued… The second type of supports addresses that are for IPv4 only. IPv4-mapped IPv6 Address | 80 bits | 16 | 32 bits | | |FFFF| IPv4 address |

IPv6 Addressing Aggregatable Global Unicast Addresses Defined in [AGGR] Supports both current provider based aggregation and exchanges | 3| 13 | 8 | 24 | 16 | 64 bits | |FP| TLA |RES| NLA | SLA | Interface ID | | | ID | | ID | ID | |

IPv6 Addressing Local-Use IPv6 Unicast Address Two types Link local and Site-local  Link local  For use on single link. Purposes:  Auto-address configuration  Neighbor discovery  When no routers are present

IPv6 Addressing Local-Use continued… Routers must not forward packets with local-link source or destination address to other links. | 10 | | bits | 54 bits | 64 bits | | | 0 | interface ID |

IPv6 Addressing Local-Use continued… Second type is site-local. Used for single site. No need for global prefix. Routers must not forward any packets with site- local source or destination address outside of the site.

IPv6 Addressing Local-Use continued… Site-local format | 10 | | bits | 38 bits | 16 bits | 64 bits | | | 0 | subnet ID | interface ID |

IPv6 Addressing Anycast Addressing An address that is assigned to more than one interface. Packet with anycast address is routed to “nearest” interface with that address. Allocated from unicast address space.  Syntactically no different from unicast

IPv6 Addressing Anycast Addressing continued… When a unicast address is turned into an anycast address, nodes to which that address is assigned must be configured to know that it is an anycast address. For any assigned anycast address, there is a longest address prefix P. Identifies the topological region where all interfaces belonging to that anycast address live.

IPv6 Addressing Anycast Addressing continued… Within the region identified by P, Each member of anycast set must be advertised as separate entity in routing system. For regions identified outside of P,  Anycast address may be aggregated into the routing advertisement for prefix P.

IPv6 Addressing Anycast Addressing continued…  Problem is that P may not have topological locality.  Support for “global” anycast sets may be unavailable or strictly limited. Could use anycast addresses for; identifying set of routers belonging to organization that provides internet service. identifying the set of routers attached to particular subnet.

IPv6 Addressing Anycast Addressing continued… Could use anycast addresses for; identifying set of routers providing entry into particular routing domain.  Little experience with internet anycast addressing, so have restrictions.  An anycast address must not be used as the source address of an IPv6 packet.  An anycast address must not be assigned to an IPv6 host, that is, it may be assigned to an IPv6 router only.

IPv6 Addressing Anycast Addressing continued…  Required Subnet-Router anycast address format | n bits | 128-n bits | | *subnet prefix | ** |  *prefix which identifies a specific link  **interface identifier set to zero (same as unicast address for interface)

IPv6 Addressing Anycast Addresses continued… Uses for anycast  applications where a node needs to communicate with one of a set of routers on a remote subnet.

IPv6 Addressing Multicast Addresses Is an identifier for a group of nodes. | 8 | 4 | 4 | 112 bits | |* |flgs|scop| ** group ID | *  identifies the address as a multicast address **Group ID identifies the multicast group (permanent or transient)

IPv6 Addressing Multicast Addresses continued… 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.

IPv6 Addressing Multicast Addresses continued… Values of scop 0 reserved D (unassigned) 1 node-local scope E global scope 2 link-local scope F reserved 3 (unassigned) 4 (unassigned) 5 site-local scope 6 (unassigned) 7 (unassigned) 8 organization-local scope 9 (unassigned) A (unassigned) B (unassigned) C (unassigned)

IPv6 Addressing Multicast Addresses continued… Cannot be used as source addresses in IPv6 packets or in routing headers.

IPv6 Addressing Reserved Multicast Addresses FF00:0:0:0:0:0:0:0 FF01:0:0:0:0:0:0:0 FF02:0:0:0:0:0:0:0 FF03:0:0:0:0:0:0:0 FF04:0:0:0:0:0:0:0 FF05:0:0:0:0:0:0:0 FF06:0:0:0:0:0:0:0 FF07:0:0:0:0:0:0:0 FF08:0:0:0:0:0:0.0 FF09:0:0:0:0:0:0:0

IPv6 Addressing Reserved Multicast Addresses continued… FF0A:0:0:0:0:0:0:0 FF0B:0:0:0:0:0:0:0 FF0C:0:0:0:0:0:0:0 FF0D:0:0:0:0:0:0:0 FF0E:0:0:0:0:0:0:0 FF0F:0:0:0:0:0:0:0

IPv6 Addressing Reserved Multicast Addresses continued… All nodes addresses FF01:0:0:0:0:0:0:1 FF02:0:0:0:0:0:0:1 All routers addresses FF01:0:0:0:0:0:0:2 FF02:0:0:0:0:0:0:2 FF05:0:0:0:0:0:0:2

IPv6 Addressing A node’s required addresses. A host is required to recognize:  Its Link-Local Address for each interface  Assigned Unicast Addresses  Loopback Address  All-Nodes Multicast Addresses  Solicited-Node Multicast Address for each of its assigned unicast and anycast addresses  Multicast Addresses of all other groups to which the host belongs.

IPv6 Addressing A router must recognize all the addresses the host recognizes plus:  The Subnet-Router anycast addresses for the interfaces it is configured to act as a router on.  All other Anycast addresses with which the router has been configured.  All-Routers Multicast Addresses  Multicast Addresses of all other groups to which the router belongs.

IPv6 Addressing Addresses that should be predefined on implementation:  Unspecified Address  Loopback Address  Multicast Prefix (FF)  Local-Use Prefixes (Link-Local and Site-Local)  Pre-Defined Multicast Addresses  IPv4-Compatible Prefixes

Ipv6 Addressing The End

IPv6 Addressing References RFC 2373