CS221: IPv6

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The Internet Protocolversion 6 (IPv6)
Evolution or Revolution ?
Christophe Jelger Post-doctoral
researcher Christophe.Jelger_at_unibas.ch
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Plan

• Motivations behind IPv6
• IP is History
• Lack of IPv4 addresses ?
• Growth of routing tables
• Unfairness in IPv4 address allocation
• Required features of IPng
• So what's new in IPv6 ?
• Address format and scoped addresses
• IPv6 header vs. IPv4 header
• New features autoconfiguration, improved
  mobility support

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Plan

• Address allocation with IPv6
• Hierarchical routing everywhere
• Today's IPv6 world
• Where are we today ?
• Current status of IPv6
• From IPv4 to IPv6

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Motivationsbehind IPv6
When the main issues are not related to end users

Where are We today ?
Motivations Behind IPv6
So what's New in IPv6 ?
Address Allocation With IPv6
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IP is History and the Internet is growing

• The current version (4) of the IP protocol is 30
  years old
• IP is everywhere it has become the de facto
  standard
• The Internet is growing
• 1973 research network (100 machines)
• Mid-80s early adoption and first address
  allocations
• 1992 First commercial applications and start of
  the Web
• 1993 first address crisis CIDR introduced
• no more addresses by 1994 !
• Exponential growth
• 2002 600 million Internet users

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Lack of IPv4 addresses ?

• A very hot topic
• Address exhaustion was predicted many times
• Current estimates 5 to 20 years to go
• 2011-2012 IANA unallocated address space is
  assigned
• 2026 exhaustion of the RIRs' address spaces
• Drawback is that getting addresses becomes very
  difficult
• Address allocation is strongly unfair
• IPv4
• Address length is 32 bits theoretically, that
  is 4.5 billion addresses
• But addressing is not so simple
• Allocation is network-based

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Lack of IPv4 addresses ?

• Class-based address architecture

Network id
Host id
32 bits
Class A network 127 networks each with 16,777,216
hosts
8 bits
24 bits
Class B network 16,128 networks each with 65,536
hosts
16 bits
16 bits
Class C network 2,031,616 networks each with 256
hosts
8 bits
24 bits
1993 no Class B networks available !
Class-less Inter-Domain Routing (CIDR) introduced
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Lack of IPv4 addresses ?

• CIDR
• Allows network-id of any length (e.g. /13, /26)
• E.g. /18 16384 hosts and /19 8192 hosts
• Aggregation and hierarchical routing
• An ISP get a /15 address space and it
  redistributes sub-parts of it, e.g. 512 /24
  networks
• Routing to all the ISP's clients is done via the
  /15
• Also adddress allocation became more strict

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Lack of IPv4 addresses ?

• CIDR solved the problem until when ?
• Around 41 /8 are still available (78 in November
  2004)
• At the current pace, 5 /8 (100M addresses !) are
  used every year, but this rate is growing as
  emerging countries are hungry in addresses
  (China, India, African countries)
• Address allocation is becoming a nightmare
• We must move ahead before it's too late
• Still a big waste of address space
• UniBasel 8500 active machines but a /16 network
  (65,536 hosts)
• Non-ISP entities still have a /8 address space
  (IBM, HP, Xerox, Apple, MIT, Ford, Lily,
  Halliburton)
• BUT the problem is not only the lack of addresses
  

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Growth of routing tables

• In the core part of the Internet, routers do not
  have a default route this is the Default-Free
  Zone (DFZ)
• In 2000, the size of routing tables in the DFZ is
  around 75,000 entries
• In 2001, it is around 100,000
• In December 2004, this value is between 150,000
  and 180,000
• In April 2007, this value reaches 300,000 for
  some ASs !
• In April 2008, about 255,000 prefixes for AS2.0
  (APNIC RD).
• Routing updates are getting slower
• Operational maintenance becomes more and more
  complex

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Growth of routing tables

• Main cause aggregation is not sufficient
• The top 30 operators could reduce their
  announcements by 64.1 with proper aggregation
  (68 in 2007, 67 in 2006, 60 in 2005)
• The DFZ size could be reduced by 35.9 with
  aggregation for all ASs (50 in 2007, 34 in
  2006, 30 in 2005)
• Aggregation alone cannot significantly reduce the
  size of the DFZ A complete address re-allocation
  should be made
• 131.152.0.0/16 UniBasel 131.153.0.0/16
  Sematech, TX
• THIS IS IMPOSSIBLE !
• Except if a new addressing scheme is used IPv6 !

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Unfairness in address allocation

• Historically, addresses have been assigned on a
  first-come first-serve basis
• But today, addresses are assigned in a very
  strict way
• Some countries fail to obtain sufficient
  addresses
• When others have far too many addresses
• United States 4.2 addresses / inhabitant (9.4
  per Internet user)
• Switzerland 1.4 addresses / inhabitant (4 per
  Internet user)
• France 0.6 addresses / inhabitant (3.4 per
  Internet user)
• China 0.02 addresses / inhabitant (0.54 per
  Internet user)
• India 0.003 addresses / inhabitant (0.38 per
  Internet user)
• Senegal 8.192 addresses (10M inhabitants)
• Mali 4.096 addresses (13 M inhabitants)
• Congo 0 addresses (52 M inhabitants)

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Required features of IPng (next generation)

• RFC-1380 from IESG (Internet Engineering
  Steering Group)
• IPng must be capable of addressing 1012 networks
• Transition to IPng must be done without the need
  of a D-day
• IPng must be easily extended with new features
• Deployment features
• Hierchical routing MUST be the norm
• Getting an address space must be straightforward
• Autoconfiguration

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So what's new in IPv6 ?
Myths and reality
Where are We today ?
Motivations Behind IPv6
So what's New in IPv6 ?
Address Allocation With IPv6
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Address format and scoped addresses (RFC 3513)

• 128 bits (16 octets)
• That is potentially 3.4 x 1038 addresses
• And 1.8 x 1019 /64 networks !
• 64-64 is the norm a /64 network can accommodate
  any number of devices !
• Notation
• IPv4 131.152.230.33/16
• IPv6 20016202001200e2fffe9c2282/64
• 200162020010001 ? 200162020011
• New DNS record AAAA (A for IPv4)

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Address format and scoped addresses

• Scoped addresses
• Link-local addresses prefix fe80/64
• Site-local (deprecated) prefix fec0/64
• Unique local (address scope is global but routing
  is restricted to a site) prefix fc00/7 (but
  /64 when deployed)
• Multicast ff00/8
• Link-scope ff02/16
• Site-scope ff05/16
• Global-scope ff0e/16
• Well-known addresses no layer-3 broadcast any
  more
• ff021 all nodes on link, ff022 all routers on
  link
• ff0216 all MLDv2 multicast routers

• Special addresses
• Loopback 00000001 or 1
• Unspecified 00000000 or

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IPv6 header vs. IPv4 header (RFC 2460)
20 bytes (without option)
40 bytes
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IPv6 header vs. IPv4 header

• Header format is simplified
• Optional headers are daisy-chained
• No checksum at IP layer (it's done by other
  layers)
• No re-computation by each router
• No hop-by-hop segmentation
• Path MTU discovery
• 64 bits aligned
• ARP (address Resolution Protocol) is replaced by
  Neighbor Discovery at the ICMP6 layer

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IPv6 header vs. IPv4 header

• Optional headers
• Hop-by-Hop header information that must be
  processed by all intermediate hops
• Used by ICMP6 (MLD, Multicast Listener Discovery)
• Routing header the source node can specify one
  or multiple intermediate hops via which the
  packet must travel (source-routing)
• Used by Mobile IPv6
• Fragment header to send a packet which has a
  size gt MTU
• Destination option to carry additional
  information that must be processed by the
  destination
• Used by Mobile IPv6

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New features

• Stateless Address Autoconfiguration (RFC 2462)

MAC 000785927FF8
IPv6 router
Prefix EUI-64 (universal bit)
IPv6 prefix
20016604701f00220785fffe927ff8/64
20016604701f002/64
also internally done for fe8020785fffe927ff8/
64
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New features ICMPv6

• Neighbor Discovery (RFC 2461)
• Main feature is the replacement of ARP

IPv6 fe8020785fffe927ff8/64 MAC
000785927FF8 3333ff927ff8
IPv6 fe8020b5dfffe589eec/64 MAC
000B5D589EEC
Neighbor sollicitation
Neighbor advertisement
Eth dst addr 3333ff927ff8 (multicast MAC
address) IPv6 dst addr ff021ff927ff8
(sollicited multicast address) Target
fe8020785fffe927ff8
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New features

• Stateless Address Autoconfiguration
• Duplicate Address Detection (DAD)
• Security issues and DNS dynamic updates are
  currently being investigated by IETF.
• Who's behind which machine ? (URZ)
• Improved support for
• Mobility (Mobile IPv6)
• Security (IPSec) is integrated
• Multicast deployment through RP-embedded
  addresses
• Myths IPv6 does NOT provide
• Any QoS features
• Any kind of improved performance

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Address Allocationwith IPv6
Where the BIG difference is
Where are We today ?
Motivations Behind IPv6
So what's New in IPv6 ?
Address Allocation With IPv6
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AGUA (Aggregatable Global Unicast Addresses)
Host
Site
Provider
64 bits
16 bits
45 bits
3 bits 001
SLA
Global Routing Prefix
Host ID

• Current allocation scheme
• IANA has decided to start with 2001/16
• IANA allocates /23 to registries
• RIPE (Europe) 2001600/23
• ARIN (North America) 2001400/23
• APNIC (Asia) 2001200/23
• Registries allocate /32 to ISP
• SWITCH 2001620/32
• RENATER 2001660/32

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Allocation Scheme

• ISP allocate /48 or /64 to customers
• UniBasel 2001620200/48
• UniStrasbourg 20016604701/48
• /64s are for end users (via ADSL or cable)
• Hierarchical routing IS the norm
• With IPv4, SWITCH announces 94 prefixes (could be
  reduced to 91) which CANNOT be aggregated !
• With IPv6, SWITCH announces one prefix !
  (2001620/32)
• Current DFZ size is around 1100, 850 in 2007
  (250,000-300,000 for IPv4!)
• Proper aggregation could reduce this by 5.8 (4
  in 2007).
• Max DFZ until re-allocation is 4096

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Today's IPv6 world

• Only 0.0008 of the entire IPv6 address space is
  used ! (i.e. the equivalent of about 160,000
  billion /64 networks !)
• In 2007, 0.0008 and 152,000 billion /64s
• In 2006 0.0007 and 130,000 billion /64s
• In 2005 0.0005 and 90,000 billion /64s
• IPv6 ready-networks WIDE, Geant (european
  academic network), Internet2 (US academic
  network), AOL, Swisscom, NASA, FT, BT etc
• Deployment in end-sites is slow
• IPv6 is not a revolution not much added value
  for end-users
• Developed countries have plenty of IPv4 addresses
• Still, IPv6 will eventually replace IPv4 it's a
  matter of time !

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Where are we today ?
Status of IPv6 specifications
Where are We today ?
Motivations Behind IPv6
So what's New in IPv6 ?
Address Allocation With IPv6
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IPv6 status

• Most part of the protocol is specified and has
  proved to work well (around 10 years of
  experimentation)
• Areas that are currently considered
• Default router selection and specific routes
  (multi-homing)
• Load sharing
• Privacy extensions for address autoconfiguration
• Secure DNS update and secure autoconfiguration
• Most systems are IPv6-ready
• BSD, Linux, Windows 2000 and XP
• Cisco, Juniper, and 6Wind routers
• Most applications are also IPv6-ready

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From IPv4 to IPv6

• Transition is difficult
• End-users and end-sites do not feel concerned
• There is no killer application for IPv6
• Many transitioning tools available
• Dual-stack
• Tunneling techniques 6to4, ISATAP
• Translation tools NAT-PT, DSTM
• Sooner or later IPv6 will prevail
• In networks with IPv4 addresses dual-stack is
  best
• In native IPv6 networks, tunneling or translation
  is needed to reach IPv4 world

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Thank you
Questions ?