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CSCI 465 D ata Communications and Networks Lecture 25

CSCI 465 D ata Communications and Networks Lecture 25. Martin van Bommel. IP Versions. IP v 1-3 defined and replaced IP v4 - current version IP v5 - streams protocol IP v6 - replacement for IP v4 during development it was called IPng (IP Next Generation). Why Change IP Versions?.

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CSCI 465 D ata Communications and Networks Lecture 25

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  1. CSCI 465Data Communications and NetworksLecture 25 Martin van Bommel CSCI 465Data Communications & Networks

  2. IP Versions • IP v 1-3 defined and replaced • IP v4 - current version • IP v5 - streams protocol • IP v6 - replacement for IP v4 • during development it was called IPng (IP Next Generation) CSCI 465Data Communications & Networks

  3. Why Change IP Versions? • Address space exhaustion: • 2 level addressing (network and host) wastes space • IP network addresses used even if not connected • Growth of networks and the Internet • extended use of TCP/IP – e.g. TV, point-of-sale • single address per host not flexible • Requirements for new types of service • address configuration • Routing flexibility - traffic support CSCI 465Data Communications & Networks

  4. IPv6 Enhancements • expanded 128 bit address space • improved option mechanism • most not examined by intermediate routes • dynamic address assignment • increased addressing flexibility • unicast, anycast, and multicast • support for resource allocation • labeled packet flows CSCI 465Data Communications & Networks

  5. IPv6PDU(Packet) Structure

  6. IPv6 Header CSCI 465Data Communications & Networks

  7. IP v6 Flow Label • related sequence of packets - special handling • identified by source and destination address + flow label • flow number generated randomly • make sure not to reuse within lifetime of old flow • router treats packets of flow the same • treatment pre-negotiated with router(s) CSCI 465Data Communications & Networks

  8. IPv6 Addresses • 128 bits long • Assigned to interface • Same interface may have multiple addresses • Types of addresses • Unicast – single interface address • Anycast – one of a set of interface addresses • Multicast – all of a set of interface addresses CSCI 465Data Communications & Networks

  9. Hop-by-Hop Options • must be examined by every router • if unknown discard/forward handling is specified • next header – type of header that follows • header extension length – length of this header • Options • Jumbo payload • IPv6 packet is longer than 65,535 octets • Router alert • Tells router(s) that packet contains router control data CSCI 465Data Communications & Networks

  10. Fragmentation Header • fragmentation only allowed at source • no fragmentation at intermediate routers • node must perform path discovery to find smallest MTU (maximum transmission unit) of intermediate networks • set source fragments to match MTU • otherwise limit to 1280 octets • minimum MTU must be supported by networks CSCI 465Data Communications & Networks

  11. Routing Header • contains a list of one or more intermediate nodes to be visited on the way to a packet’s destination • Includes • Next header identification, Header length, Routing type • Segments left – number of route segments left • Type 0 routing – IPv6 header has address of router • Routing header contains list of router addresses • Next destination address first on list • Final destination address last on list • Each router on path moves address to IPv6 header and shortens list CSCI 465Data Communications & Networks

  12. IPv6 Extension Headers CSCI 465Data Communications & Networks

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