1IPv6 and OverlaysEE122Introduction to Communication NetworksDiscussion Section2IPv6: Motivation Need for a larger address space- Explosive growth- Under-utilization by class A/B/C addresses- MinusCIDR, NAT increase usable address space+ PlusWireless sensor networks, ubiquitous computing require small devices have IP addresses3Packet FormatFrom wikipedia4Larger address is not everything Headers structure is made to improve the performance of routing (from wikipedia) No fragmentation- PMTU discovery is needed No checksum Flow label – QoS management IPsec Multicast5Comparison of IPv4 and IPv6YesNoMulticastYesNoIPsecYesNoQoSNoYesChecksumNot supportedSupportedFragmentation128 bits32 bitsAddress SizeIPv6IPv46Limitation of IP layer services QoS- Payment issue IPsec- End-to-End argument Multicast27Internet Today Changes in the network happen very slowly- IPv6 not deployed widely yet- Other examples: IPSEC (93), IP Multicast (90) Why?- Internet network is a shared infrastructure; need to achieve consensus (IETF)- Many of proposals require to change a large number of routers (e.g., IP Multicast, QoS); otherwise end-users won’t benefit - One size does not fit all• Different applications have different requirements8Goals Make it easy to deploy new functionalities in the network Æ accelerate the pace of innovation Allow users to customize their service9One Solution Deploy processing in the network Have packets processed as they traverse the networkAS-1IPAS-1Overlay Network(over IP)10ExampleDefault IP path determined by BGP & OSPFReroute traffic using red alternative overlay network path, avoid congestion pointActs as overlay routerBerkeleyMITUCLA11Resilient Overlay Network (RON) Premise: by building application overlay network, can increase performance and reliability of routing Install N computers at different Internet locations Each computer acts as an overlay network router- Between each overlay router is an IP tunnel (logical link)- Logical overlay topology is all-to-all (N^2) Computers actively measure each logical link in real time for- Packet loss rate, latency, throughput, etc Route overlay network traffic based on measured characteristics12What about P2P networks? Some overlays are p2p networks Some p2p networks are
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