IPv6 and Overlays EE122 Introduction to Communication Networks Discussion Section IPv6 Motivation Need for a larger address space Explosive growth Under utilization by class A B C addresses Minus CIDR NAT increase usable address space Plus Wireless sensor networks ubiquitous computing require small devices have IP addresses 2 Packet Format From wikipedia 3 Larger 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 Multicast 4 Comparison of IPv4 and IPv6 IPv4 IPv6 Address Size 32 bits 128 bits Fragmentation Supported Not supported Checksum Yes No QoS No Yes IPsec No Yes Multicast No Yes 5 Limitation of IP layer services QoS Payment issue IPsec End to End argument Multicast 6 Internet 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 requirements 7 Goals Make it easy to deploy new functionalities in the network accelerate the pace of innovation Allow users to customize their service 8 One Solution Deploy processing in the network Have packets processed as they traverse the network AS 1 AS 1 IP Overlay Network over IP 9 Example MIT Berkeley Default IP path determined by BGP OSPF UCLA Reroute traffic using red alternative overlay network path avoid congestion point Acts as overlay router 10 Resilient 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 characteristics 11 What about P2P networks Some overlays are p2p networks Some p2p networks are overlays 12
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