3Chapter IPv6

• The Internet Engineering Task Force (IETF) is the organization that is responsible for defining the Internet Protocol standards
• When the IETF developed IPv4, the global expansion of the Internet and the current Internet security issues were not anticipated
• In IPv4's original design, network security was only given minor consideration
• As IPv4 was developed and the Internet explosion took place in the 1990s, Internet threats became prolific
• IPv6


  The replacement Internet protocol for IPv4

  
• IPv4


  • It has proven to be robust, easily implemented, and interoperable, and has stood the test of scaling an internetwork to a global utility the size of the Internet
• Deficiencies of IPv4


  • Recent exponential growth of the Internet and the impending exhaustion of the IPv4 address space
  • The ability of Internet backbone routers to maintain large routing tables
  • Need for simpler autoconfiguration and renumbering
  • Requirement for security at the IP level (IPSec)
  • Need for better support for real-time delivery of data, known as quality of service (QoS)

  
• IPv4 address format


  32-bit, can handle a maximum 4.3 billion unique IP addresses

  
• IPv6 address format


  128-bit, can support 3.4 x 10^38 or 340,282,366,920,938,463,463,374,607,431,768,211,456 unique IP addresses

  
• The number of IPv4 addresses is not enough to sustain and scale the rapidly rising growth of the Internet
• Improvements to IPv4, including the use of NAT, have allowed the extended use of the protocol, but address exhaustion is inevitable
• In the early 1990s, the IETF realized that a new version of IP would be needed, and the Task Force started by drafting the new protocol's requirements
• IP Next Generation (IPng)


  The new protocol that became IPv6 (RFC 1883)
• IPv6 is the second network layer standard protocol that follows IPv4 for computer communications across the Internet and other computer networks

  
• Improvements in IPv6 over IPv4

  • Increased address size from 32 bits to 128 bits
  • Streamlined protocol header: Improves packet-forwarding efficiency
  • Stateless autoconfiguration: The ability for nodes to determine their own address
  • Multicast: Increased use of efficient one-to-many communications
  • Jumbograms: The ability to have very large packet payloads for greater efficiency
  • Network layer security: Encryption and authentication of communications
  • Quality of service (QoS) capabilities: QoS markings of packets and flow labels that help identify priority traffic
  • Anycast: Redundant services using nonunique addresses
  • Mobility: Simpler handling of mobile or roaming nodes

  
• IPv6 address


  128 bits long, logically divided into a network prefix and a host identifier

  
• The number of bits in the network prefix is represented by a prefix length (for example, /64)

  
• If you do not specify a prefix length for an IPv6 address, the default prefix length is /64

  
• Representing IPv6 in binary format

  1. Break the 128 bit binary into 8 blocks each of 16 bits

  2. Split each block into 4 segments of 4 bits

  3. Convert each segment into hexadecimal notation

  
• Zero compression


  If there is more than one consecutive block where the characters are all zeros you can compress them to :: (a double colon)
• Zero suppression


  Leading zeros can be omitted
• Double colons can appear only once in the IPv6 address
• IPv6 prefixes


  Similar to IPv4 CIDR network prefix representation, an IPv6 address network prefix is represented the same way: 2001:db8:12::/64

  
• The bits on the left of an IPv6 address (high-order bits) specify the network, the other bits specify particular addresses in that network

  
• Advantages of IPv6


  • Simplified header format for efficient packet handling
  • Larger payload for increased throughput and transport efficiency
  • Hierarchical network architecture for routing efficiency
  • Support for widely deployed routing protocols (OSPF, BGP, etc.)
  • Autoconfiguration and plug-and-play support
  • Elimination of need for network address translation (NAT) and application layered gateway (ALG)
  • Increased number of multicast addresses

  
• Methods for configuring IPv6 host ID

  • Using a randomly generated number
  • Using DHCPv6
  • Using the Extended Unique Identifier (EUI-64) format

  
• Features of IPv6


  • Larger Address Space
  • Faster Forwarding/Routing
  • Simplified Header
  • End-to-end Connectivity
  • Auto-configuration
  • IPSec
  • No Broadcast
  • Anycast Support
  • Mobility
  • Enhanced Priority Support

  
• IPsec


  Allows IPv6 packet authentication and/or payload encryption via the Extension Headers

  
• IPsec is not automatically implemented, it must be configured and used with a security key exchange
• Broadcast


  Ethernet/Token Ring are considered as broadcast network because they support Broadcasting, IPv6 does not have any broadcast support any more
• Multicast


  IPv6 uses multicast to communicate with multiple hosts
• Anycast


  IPv6 has introduced Anycast mode of packet routing where multiple interfaces over the Internet are assigned same Anycast IP address, and routers send the packet to the nearest destination

  
• Mobility


  Enables hosts (such as mobile phone) to roam around in different geographical area and remain connected with the same IP address, taking advantage of auto IP configuration and Extension headers
• Traffic class and Flow label

  Used in IPv6 to tell the underlying routers how to efficiently process the packet and route it

  
• Smooth Transition


  Large IP address scheme in IPv6 enables to allocate devices with globally unique IP addresses, saving IP addresses and not requiring NAT

  
• As the header is less loaded, routers can take forwarding decisions and forward them as quickly as they arrive
• Extensibility


  IPv6 header is extensible to add more information in the option part, unlike IPv4 which provides only 40-bytes for options

  
• Unicast address


  Identifies a single node or interface, traffic destined for a unicast address is forwarded to a single interface

  
• Multicast address


  Identifies a group of nodes or interfaces, traffic destined for a multicast address is forwarded to all the nodes in the group

  
• Broadcast addresses are no longer used in IPv6, they are replaced by multicast addresses