IPv6 Addressing Internet2 IPv6 Workshop Research Triangle Park, NC 5-7 March 2002

2 Overview of Addressing Historical aspects Types of IPv6 addresses Work-in-progress Abilene IPv6 addressing

3 Historical Aspects of IPv6 IPv4 address space not big enough Can’t get needed addresses (particularly outside Americas) Resort to private (RFC1918) addresses Competing plans to address problem Some 64-bit, some 128-bit Current scheme unveiled at Toronto IETF (July 1994)

4 Types of IPv6 Addresses Like IPv4… Unicast Multicast Anycast …but designed into specifications from the beginning

5 Representation of Addresses All addresses are 128 bits Write as sequence of eight sets of four hex digits (16 bits each) separated by colons Leading zeros in group may be omitted Contiguous all-zero groups may be replaced by “::” Only one such group can be replaced

6 Examples of Writing Addresses 3ffe:3700:0200:00ff:0000:0000:0000 :0001 can be written 3ffe:3700:200:ff:0:0:0:1 or 3ffe:3700:200:ff::1

7 Interface Identifiers Sixty-four bit field Guaranteed unique on subnet Essentially same as EUI-64 Formula for mapping IEEE 802 MAC address into interface identifier Used in many forms of unicast address

8 Types of Unicast Addresses Unspecified address All zeros (::) Used as source address during initialization Also used in representing default Loopback address Low-order one bit (::1) Same as in IPv4

9 Types of Unicast Addresses Link-local address Unique on a subnet Result of router discovery or neighbor discovery High-order: FE80::/64 Low-order: interface identifier Site-local address Unique to a “site” High-order: FEC0::/48 Low-order: interface identifier What is a site?

10 Types of Unicast Addresses Mapped IPv4 addresses Of form ::FFFF:a.b.c.d Used by dual-stack machines to communicate over IPv4 using IPv6 addressing Compatible IPv4 addresses Of form ::a.b.c.d Used by IPv6 hosts to communicate over automatic tunnels

11 Types of Unicast Addresses Aggregatable global unicast address Used in production IPv6 networks Goal: minimize global routing table size From range 2000::/3 Three fields in /64 prefix –16-bit Top Level Aggregator (TLA) –8-bit reserved –24-bit Next Level Aggregator (NLA) –16-bit Site Level Aggregator (SLA)

12 Types of Unicast Addresses Aggregatable global unicast address

13 Top-Level Aggregators Allocated by RIRs to transit providers In practice, RIRs have adopted “slow- start” strategy Start by allocating /35s Expand to /29s when sufficient use in /35 Eventually move to /16s

14 Abilene sTLA Allocated 2001:468::/35

15 NLAs and SLAs NLAs used by providers for subnetting Allocate blocks to customers Can be multiple levels of hierarchy SLAs used by customers for subnetting Analogous to campus subnets Also can be hierarchical

16 Other Unicast Addresses Original provider-based Original geographic-based GSE (8+8) Hain’s Internet Draft for provider- independent (geographically-based) addressing

17 Multicast Address From FF00::/8 Address contains four-bit scope field Unlike IPv4 multicast, scope is explicitly defined in address Low-order 112 bits are group identifier, not interface identifier

18 Anycast Address Used to send packets to all interfaces on a network (like IPv4 anycast, not all will necessarily respond) Low-order bits (typically 64 or more) are zero

19 Abilene IPv6 Addressing Two prefixes allocated 3ffe:3700::/24 on 6bone 2001:468::/35 sTLA Planning migration from 6bone addressing Current addressing plan built on assumption of /35

20 Allocation Procedures GigaPoPs allocated /40s Expected to delegate to participants No BCP (yet) for GigaPoP allocation procedures Direct connectors allocated /48s Will (for now) provide addresses to participants behind GigaPoPs which haven’t received IPv6 addresses See WG web site for details

21 Registration Procedures Providers allocated TLAs (or sTLAs) must register suballocations ARIN allows rwhois or SWIP For now, Abilene will use SWIP Will eventually adopt rwhois GigaPoPs must also maintain registries –Will probably have central Abilene registry

22 Obtaining Addresses Drop a note to Abilene NOC with Will set wheels in motion