Questions Why cant we measure the Internet more directly u What can we do about

Questions why cant we measure the internet more

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Questions Why can’t we measure the Internet more directly? u What can we do about it? Right division of labor between host and network? u For path selection u For network monitoring How do we fix these routing problems? u In a decentralized, federated network u How to incentivize better network management 11 CSE 222A – Lecture 4: Routing
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Internet “Ossification” Internet protocols evolve over long timescales u Witness the paper we just read from 1974 u IPv6 was proposed over 20 years ago now! (RFC2460) Yet new ideas appear all the time u RFCs are now at 8500+ u SIGCOMM/NSDI/etc. are full of new protocols/architectures Key challenge: how to deploy new things STAT? u In particular changes to the networking layer u Would naively require changing every router on the Internet! 12 CSE 222A – Lecture 4: Routing
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Obvious solution: Overlays Build the service at a layer above IP u Create an “overlay” of nodes connected by IP u Functionality implemented at IP “end hosts” and forwarded on u IP provides “tunnels” between nodes of overlay Exactly the same approach originally used by IP u IP treated the phone network as a series of tunnels Used to introduce a variety of services in the ‘90s u M-Bone, X-Bone, A-Bone, etc., etc. Major downside is performance u Each packet needs to be handled by an end host u Likely traverses an inefficient route 13 CSE 222A – Lecture 4: Routing
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An Alternative Approach Make the routers extensible: Active Networking u Provide a mechanism to implement services at an Internet router u Removes the need to route indirectly u But still requires additional end-host-like processing Same idea, two different layers u Active nodes are implemented at the (extended) network layer u
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  • Fall '08
  • Vahdat,A
  • Paxson

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