Download - IPv6 Addressing
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IPv6 Addressing
Internet2 IPv6 Workshop
Research Triangle Park, NC
5-7 March 2002
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Overview of Addressing
Historical aspects
Types of IPv6 addresses
Work-in-progress
Abilene IPv6 addressing
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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)
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Types of IPv6 Addresses
Like IPv4…• Unicast• Multicast• Anycast
…but designed into specifications from the beginning
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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
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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
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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
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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 127.0.0.1 in IPv4
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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?
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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
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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)
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Types of Unicast Addresses
Aggregatable global unicast address
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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
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Abilene sTLA
Allocated 2001:468::/35
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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
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Other Unicast Addresses
Original provider-based
Original geographic-based
GSE (8+8)
Hain’s Internet Draft for provider-independent (geographically-based) addressing
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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
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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
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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
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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
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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
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Obtaining Addresses
Drop a note to Abilene NOC ([email protected]) with request
Will set wheels in motion