IPv6 The New Internet Protocol

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IPv6The New Internet Protocol

• Integrated Network Services
• Almerindo Graziano

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Introduction

• Justification for IPv6
• IPv6 goals
• IPv6 Addressing
• The new Header
• Extension Headers
• Recap

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Justification for IPv6 What is wrong with IPv4?

• Wasteful of address space
• Not built-in support for hierarchical addressing
• Subnetting
• CIDR
• Large routing tables
• Large administrative workload
• Changing ISP
• Merger or acquisition

Renumbering or NAT
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What is wrong with IPv4?

• Routers perform a lot of operations
• Table lookup
• Options
• Checksum
• Fragmentation
• Lack of authentication
• IP spoofing
• Lack of encryption

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IPv6 goals

• Support for a larger number of addresses
• Reduce the size of routing tables
• Simplify the protocol (easier to process)
• Provide better security
• Better support for Quality of Service
• Provide support for mobile users
• Allow the protocol to be extensible
• Be compatible

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IPv6 Addressing scheme

• Designed to be highly scalable and hierarchical
• 16-byte long
• 7x1023 IP addresses per square meter!!!
• It eliminates the need for private address
  space
• IPv6 notation
• 800000000000000001238219E42ADF3E
• 80001238219E42ADF3E
• IPv4 addresses can be written as
• 192.31.20.46

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Address Allocation

• IPv6 could support a number of diverse addressing
  schemes
• Provider Allocation
• hierarchy is based on large service providers,
• regardless of their location
• Geographic Allocation
• hierarchy is based on the location of subscribers
• (similar to the telephony system)
• Both approaches have drawbacks
• Large networks do not often conform to provider
• and/or geographical boundaries!!

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Aggregation Based Allocation

• Combines provider and geographic allocation
  approaches
• Based on the existence of limited number of
  high-level exchange points
• Large providers are represented at one or more
  exchange points (provider orientation)
• Exchanges are distributed around the globe
  (geographic orientation)
• Favoured by the IETF

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IPv6 Address Hierarchy
To other TLA
TLA Top Level Aggregator
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Aggregation-based Allocation

• First 3 bits identify the type of address
• unicast, multicast, anycast etc..
• International registries assign block to TLA
• TLA allocate block of addresses to NLA
• NLA can be large providers or global corporate
  networks
• NLA can create their own hierarchy

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Aggregation-based Allocation
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Other Address Types

• Site-Local Addresses
• Similar to IPv4 private addresses
• Link-Local Addresses
• A router doesnt exist
• Operate over a single link
• Used for temporary bootstrapping
• Not propagated outside organizational boundaries
• Not allocated by public registry authorities

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Other Address Types

• Multicast Addresses
• Logical addresses to communicate to multiple
  nodes
• Anycast Addresses
• Used to communicate to the closest of a class of
  nodes (closest DNS, closest router)
• Allocated from the same address space as Unicast
  addresses

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Address Autoconfiguration

• A node combines its MAC address with a network
  prefix it learns from a neighbouring router
• The autoconfiguration doesnt need a manually
  configured server stateless address
  autoconfiguration
• It differs from IPv4s DHCP (stateful address
  configuration). DHCPv6 has been developed
• Great advantage when an enterprise is forced to
  renumber because of an ISP change or MA
• Great support for mobile users and dynamic
  workgroups

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IPv4 Header
Header Comparison
IPv6 Header
IPv4 Header 14 fields IPv6 Header 8 fields
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The new Header

• Fixed size
• Fewer fields
• No Checksum
• Already performed by other layers
• Reliable networks
• Extension Headers replace Options
• Routers can skip over some extension headers
• Faster processing
• Extensible

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QoS Support

• Priority field (4 bits)
• Congestion-Controlled traffic (0-7)
• Traffic where the source backs off in case of
  congestion (e.g. TCP)
• Non-Congestion-Controlled traffic (8-15)
• Traffic where constant data rate and delay are
  desirable (real-time audio/video)
• Flow label field (20 bits)
• A sequence of packets sent from a particular
  source to a particular destination for which the
  source desires special handling by intervening
  routers

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Extension Headers

• Hop-by-Hop options header
• Destination options header-1
• Source Routing header
• Fragmentation header
• Authentication header
• IPv6 Encryption header
• Destination options header-2

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Extention Headers

• Hop-by-Hop
• Carries information for all intermediate nodes
• Used for management and debugging
• Destination
• Carries information to be read just by
  destination nodes
• Source Routing
• Allows to specify a list of router to traverse

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Fragmentation Header

• Each source is responsible for sending packets of
  the right size
• MTU path discovery process
• Packet fragmentation is not permitted by
  intermediate nodes (routers)
• Faster processing
• If fragmentation is required, the fragmentation
  header is used

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Authentication Header

• It gives network applications a guarantee that a
  packet did in fact come from an authentic source
• A checksum is created based on the key and the
  content of the packet
• The checksum is re-run at the destination and
  validated

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IPv6 Encryption Header

• Encapsulation Security Payload (ESP)
• It provides encryption at the network layer
• Two encryption modes are supported
• Transport mode
• Tunnel mode (steel pipe)

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Encryption modes
Transport Mode
Tunnel Mode
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The Transition to IPv6

• IPv6 offers a robust future-oriented solution to
  integrate physical networks
• Possibly use NAT but
• can be a bottleneck
• prevents the use of IP-level security
• breaks Domain Name Servers
• 6Bone
• Experimental world-wide network for testing IPv6

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IPv6 Resources

• Main IPv6 page
• http//ipv6.com/
• 6Bone home page
• http//6bone.net/
• The case for IPv6 (Internet Draft)
  http//www.6bone.net/misc/case-for-ipv6.html