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Internet Protocol version 6

Internet Protocol version 6. Devpratim Chakraborty Ayaz Lalani ECE 4605 Prof: Siva. Connectin Lives~. Outline. Introduction – IPv6 Header Format Extension Headers Several types of extension headers Packet Size Flow Labels Upper-Layer Protocols IPv4 vs. IPv6. Introduction.

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Internet Protocol version 6

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  1. Internet Protocol version 6 Devpratim Chakraborty Ayaz Lalani ECE 4605 Prof: Siva Connectin Lives~

  2. Outline • Introduction – IPv6 • Header Format • Extension Headers • Several types of extension headers • Packet Size • Flow Labels • Upper-Layer Protocols • IPv4 vs. IPv6

  3. Introduction • Next generation protocol designed by IETF • Improvised IPv4 • Backwards compatibility • Growing applicability • Mail Clients • DNS • Multimedia • Remote Access

  4. Header Format 0 4 12 16 24 31 Version Traffic class Flow label Payload length Next header Hop limit Source address Destination address

  5. Extension Headers • All extension headers start with “next header” field • Hop-by-hop header • Destination Options header • Routing header: specifies nodes to be visited on the way • Fragment header • Authentication header • Encapsulating security payload header • Destination Options header: information to be examined only by the destination host • Upper-Layer Header Why Extension Headers

  6. Options Pad1, PadN • Option Type • First two bits (00, 01, 10, 11) • Third bit (0, 1) • Padding (Pad1, PadN) • Examples: • Hop-by-Hop • - 0 • Destination Options • - 60

  7. Routing Header Identified by Next Header value of 43 Type-specific data

  8. Routing (example)

  9. Fragment Header • Fragmentation at Source to fit path MTU • Identification values for each packet • Reassembly at Destination Fragmented Packets • Unfragmentable Part • IPv6 Header • Routing Header • Hop-by-Hop Options Header

  10. Fragment Header contd. • Reassembly • Same source, destination, identifier • Payload Length • Possible errors during reassembly • Fragment Reassembly Time Exceeded • Inconsistent Payload Length • Inconsistent Fragment Headers

  11. No Next Header • The value 59 in the Next Header field of an IPv6 header or any extension header indicates there is nothing following that header. • If the Payload Length of IPv6 header indicates the presence of more octets whose Next Header field contains a 59, those octets must be ignored, and forwarded unchanged.

  12. Packet Size • Minimum MTU of 1280 octets (default) • If unable, fragment at lower layer • Destination can reassemble up to 1500 octets • Path MTU Discovery – Efficiency!! • IPv6 Source - IPv4 Destination • ICMP Packet Too Big message • Include Fragment Header • Payload Length reduced to 1232 • Same Fragment ID => problem?!?

  13. Flow Labels • Type of Service (TOS) • “Real-Time” service • Flow Label • Random and Uniform between 1 & FFFFF • Why? • zero (non-supportive nodes, routers) • Default routers do not distinguish between flows

  14. Traffic Classes • Prioritization of packets by originating node • Differentiate services without explicit flow setup • Replaces ToS in IPv4 • General requirements • Upper-layer protocol compatibility • Leniency to change per use

  15. Upper-Layer Protocol • Upper Layer Checksums • Computation modified for 128-bit IPv6 addresses vs. 32-bit IPv4 addresses • UDP checksum is not optional for IPv6 • Next Header identifies the Upper-layer protocol • TCP – 6 • UDP – 17 • Checksum includes the Pseudo-Header!! • Different from IPv4 • Why? • Protect from misdelivery or corruption of IPv6 header fields. IPv6 Pseudo-Header

  16. Upper-Layer Protocols contd. • Maximum Packet Lifetime • IPv6 nodes are not required to enforce maximum packet lifetime • “Time to Live” of IPv4  “Hop Limit” of IPv6 • Maximum Payload Size • IPv4: Max packet size – 40 octets • IPv6: Max packet size – 60 octets

  17. Why IPv6? • Improvements over IPv4: • Expanded address space • Security and authentication • Improved option mechanism: separate optional headers • Mechanism for dynamic assignments of addresses • Improved addressing flexibility, including unicast • support for resource allocation: instead of TOS in IPv4, labeling of packets according to a traffic flow (source-destination) with predefined service characteristics

  18. Questions or comments?

  19. Puzzle • Suppose you have milk and coffee in equal quantities in two different cups. You pour some of the milk into the coffee then pour back some of the mixture back into the milk cup so that there is the same total amount of liquid in both cups once again. Is there more, less or an equal amount of milk in the coffee cup than there is in the milk cup?

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