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CS4550 Computer Networks II IP : internet protocol, part 3 : routing policies, IPv6

CS4550 Computer Networks II IP : internet protocol, part 3 : routing policies, IPv6. IP routing. routing mechanism - the mechanics of routing -- discussed previously -- review basic routing algorithm routing policy - how the paths in the network are calculated

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CS4550 Computer Networks II IP : internet protocol, part 3 : routing policies, IPv6

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  1. CS4550 Computer Networks IIIP : internet protocol,part 3 : routing policies, IPv6

  2. IP routing • routing mechanism - the mechanics of routing -- discussed previously -- review basic routing algorithm • routing policy - how the paths in the network are calculated -- there is no single required routing policy on the Internet -- DV and LS routing already discussed -- some specific IP policies to follow

  3. interior gateway protocols (IGPs) RIP IGRP, EIGRP OSPF autonomous systems exterior gateway protocols EGP BGP IPv6 IP - routing policy topics

  4. references • Feit, TCP/IP: architecture, protocols and implementation • many RFCs : RIP : 1058, 1723, 1582 OSPF : 1583,1793, 1586, 1584, 1403 BGP : 1771, 1773, 1772 IGRP : www.cisco.com

  5. Automated Routing Protocols Generic Functions • Measure route cost • Send/receive routing updates • compute routes • update routing tables

  6. routing information protocol (RIP) • most widely used; now in 2nd version • free, available with Unix as “routed” • DV routing, each hop assigned cost (usually 1) • strong points: simple and available; good for small, simple networks • max path length is 15 hops • not good for very large networks (already discussed DV problems)

  7. IGRP : internet gateway routing protocol • Cisco routers -> proprietary • distance vector protocol also • uses split horizon • updates every 90 seconds (default) • triggered updates • if no update from an adjacent router for 270 sec, entry timed out, destinations using it rerouted • destinations flushed after 540 seconds

  8. more on IGRP • more sophisticated distance metric • delay • bandwidth • congestion (load) • reliability • hop count to destination • biggest MTU (packet) that link/path can carry • can also split traffic over multiple paths • can also support routing between different autonomous systems

  9. EIGRP - enhanced IGRP • same distance metrics and routing calculations • does away with periodic updates; only updated after change, but reliable updates used • used an algorithm to detect loops in routes and remove them • “EIGRP has proven the distance vector routing is far from dead” (Feit)

  10. OSPF : open shortest path first • link state protocol, developed by IETF; non proprietary • low overhead; updates report changes rather than everything • quick detection of topology changes, rap • id updating after changes • traffic splitting over multiple paths • subnet masks supported • authentication supported • widely used, refinements will continue

  11. autonomous systems • a piece of the Internet unified by a routing policy • “somebody’s network” early def: a collection of subnetworks and hosts, interconnected by routes new def: a connected group of 1 or more IP prefixes ... which has a SINGLE and CLEARLY DEFINED routing policy

  12. autonomous systems • routing within ASs is done by IGPs, or interior gateway protocols; chosen by the controlling organization • routing between ASs is done by EGPs, or exterior gateway protocols • AS domain is identified by a unique 16-bit AS number administered by ARIN (www.arin.net)

  13. EIGRP EIGRP EIGRP EIGRP autonomous systems AS AS IGRP EGP RIP BGP AS EIGRP

  14. exterior gateway protocols EGP - an early version - simple distance vector: But NO weight used - very limited information passed between routers - useful early when Internet was small; losing its usefulness now BGP - border gateway protocol -report entire paths, avoiding loops -similar to link-state algorithm

  15. Further Internet topics • IPv6 • UDP and TCP (in next class) • domain name system • FTP • Telnet • email • HTTP • internet telephony • integrating TV, voice,video into Internet

  16. Why IP Version 6 • IPv4 Proposed in 1975, adopted in 1981 • Served well but 24 years old • Address Depletion • Explosion of in growth of routing tables • Non-heirarchical in nature • Security Issues • Routing Performance • New Applications • Telephony, video , conferencing • Piece of “the Puzzel” to enable new services

  17. IPv6 Challanges • Backward Compatibility • MUST work with existing equipment • Perpetual coexistence with IPv4 • MUST Coexist with current standards/protocols • will require new v4/v6 aware protocols to take advantage of v6 features

  18. IPv6 Routing • Routers CANNOT Fragment • guaranteed minimum 576 byte path • Shorter & Simplified Header • Faster Analysis • Most Optional Headers Ignored during routing • Hierarchical Addressing • Smaller Routing Tables • Like international phone system • Flow Control Lables

  19. IPv6 Packet Format • MUCH Simplified • Fixed Length - 40 bytes • 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 • version Traffic Class Flow Label • Payload length next header hop limit • Source Address ( 4 lines 16 bytes) • destination Address (4 lines 16 bytes) • Extension Headers 8 Optional headers Defined • Authentication (MDS) • Encapsulating Security Payload

  20. IPv6 Addressing • Address Notation X:X:X:X:X:X:X:X • Where X = 16 bits • Total 0f 128 bits • Three Address Types • Unicast • Multicast • Anycast • Global Unicast Address • 3 13 8 24 16 64 • 001 TLA ID RES NLA ID SLA ID Interface ID

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