Network Layer Support for Overlay Network John Jannotti MIT EECS Ph.D Thesis MIT LCS Parallel and Distributed Operating Systems Group Aug. 2002
Author • Postdoctoral Scholar Publish • John Jannotti, David K. Gifford, Kirk L. Johnson, M. Frans Kaashoek, James O'Toole Jr.: Overcast: Reliable Multicasting with an Overlay Network. OSDI 2000 • Eddie Kohler, Robert Morris, Benjie Chen, John Jannotti, M. Frans Kaashoek: The click modular router. TOCS 2000 • Jinyang Li, John Jannotti, Douglas S. J. De Couto, David R. Karger, Robert Morris: A scalable location service for geographic ad hoc routing. MOBICOM 2000
Outline • Problem • Packet Reflection • Path Painting
Problem • Stress : The number of times that a semantically identical packet traverses a given link • Stretch : The ratio of latency in an overlay network.
Problem E2 receives packets only after they have traversed eight links, rather than the four of a direct unicast
Packet Reflection (cont.) • Handshake mechanism • ASK • Offer • Demand
Fig. 1 Packet Reflection (cont.) • ASK • Initiate the request. • It contains a list of copies that the requester would like made on its behalf
Fig. 2 Packet Reflection (cont.) • OFFER • OFFER lists the subset of copies from the ASK that the router is willing to service • Nonce • Cryptographically generated integer
Fig. 3 Packet Reflection (cont.) • DEMAND • A DEMAND contains the nonce of the OFFER. • It will also contain the same copy info as the OFFER.
Packet Reflection (cont.) Offer + Nonce
Packet Reflection (cont.) Demand + Nonce