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

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

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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

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IP - routing policy topics

• interior gateway protocols (IGPs)
• RIP
• IGRP, EIGRP
• OSPF
• autonomous systems
• exterior gateway protocols
• EGP
• BGP
• IPv6

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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

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Automated Routing Protocols Generic Functions

• Measure route cost
• Send/receive routing updates
• compute routes
• update routing tables

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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)

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IGRP internet gateway routing protocol

• Cisco routers -gt 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

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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

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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)

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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

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autonomous systems

• a piece of the Internet unified by a routing
  policy
• somebodys 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

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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)

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autonomous systems
AS
AS
IGRP
EGP
RIP
BGP
AS
EIGRP
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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

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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

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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

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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

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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

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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

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IPv6 Addressing

• Address Notation XXXXXXXX
• 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