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Overlay Networking Research @NTG

Overlay Networking Research @NTG. Srinivasan Seetharaman Fall 2006. Overlay Networks. Overlay networks help overcome functionality limitations of the Internet by forming a virtual network on top of the IP network. Overlay nodes collaborate to offer multiple services:

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Overlay Networking Research @NTG

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  1. Overlay Networking Research@NTG Srinivasan Seetharaman Fall 2006

  2. Overlay Networks • Overlay networks help overcome functionality limitations of the Internet by forming a virtual network on top of the IP network. • Overlay nodes collaborate to offer multiple services: • Multicast (Ex: ESM, Overcast) • Alternate paths (Ex: RON, Detour, X-Bone, Brocade) • Customized forwarding (Ex: I3, Scattercast) • QoS (Ex: OverQoS, SON) • Name resolution, Intelligent routing…

  3. Overlay Networks (contd.) • Typical features: • Overlay routing is independent of IP layer routing(Possibly with functionality overlap) • End-system overlays (Ex: Skype), or Service overlays (Offer services to actual end-systems) • Each Overlay link is actually an IP route between the two overlay nodes • Each Overlay path is comprised of one or more Overlay links, inline with a certain objective

  4. Example: Latency-Optimized paths • Potential for selfish behavior. Impact varies based on the • percentage of overlay traffic • scale of overlay networks A 50ms D 20ms 20ms C B Relaying

  5. A D 20ms 20ms C B Relaying What can go wrong? • Overlay routes can violatenative layer polices- [Srini ICNP06] • Extra load on native linkscausing bottleneck issues.Serious issue when nativelayer wants load balance.- [Srini Ongoing] • Failure detected by both layers and rerouted twice,with each rerouting disrupting the optimality of the previous.- [Srini Infocom06]

  6. A D 20ms 20ms C B Relaying What can go wrong? (contd.) • Sub-optimal performance becauseof lack of cooperation. Potentiallya chicken-and-egg problem- [Srini Hotnets05] • Topology (Nodes+Links)placement is tricky- [Jinliang Infocom06, Sridhar Ongoing, YongZhu Infocom06] • Overlay routing can clash with TCP congestion control- [Ruomei Ongoing]

  7. 1. BGP Policy Violations • Example violation over Planetlab and its benefit 6.3ms lower latency = 10.48% gain • Transit policy is violated in the above example. Harvard Univ pays its provider unnecessarily and unavoidably.

  8. 3. Dual Rerouting 2 G 3 Consider a native link failure in CE • Only overlay link AE is affected. • The native path AE is rerouted over F(ACE → ACFDE) A I 3 2 4 E OVERLAY NATIVE G B I A ∞ F C H + Cost Overlay recovery: 8 E D Original: 2 Native Rerouting: 2 Overlay rerouting: 4 Time Native Failure Native Recovery Native Repair

  9. 4. ESM-Friendly Native Network • Reduce extra copies on some links • No extra copies on each link • Latency to reach C is less… If there were native layer support A D New packet replication capability Similar in spirit to REUNITE, Packet reflection C B

  10. What can go right? 0. The services listed earlier, viz. QoS, Multicast, resilience, intelligent routing, security • Improve performance of TCP using schemes like Overlay-TCP- [Pradnya Networking05] • Improve services offered at the native layer by deploying them at the overlay layer (Ex: Name resolution)- [Sridhar Ongoing] • Creating improved service-based architectures and end-system driven functionalities- Anyone interested?

  11. References • Jinliang Fan, Mostafa Ammar, "Dynamic Reconfiguration of Service Overlay Networks," IEEE INFOCOM, 2006. [PDF] • Yong Zhu and M. Ammar, "Algorithms for assigning substrate network. resources to virtual network components," IEEE INFOCOM, 2006. [PDF] • Pradnya Karbhari, M.Ammar, E. Zegura, "Optimizing End-to-End Throughput for Data Transfers on an Overlay-TCP Path", IFIP Networking, 2005. [PS] • S. Seetharaman and M. Ammar, "Characterizing and Mitigating Inter-domain Policy Violations in Overlay Routes," IEEE ICNP, 2006. [PDF] • S. Seetharaman and M. Ammar, "On the Interaction between Dynamic Routing in the Overlay and Native Layers," IEEE INFOCOM, 2006. [PDF] • S. Seetharaman and M. Ammar, "Overlay-Friendly Native Network: A Contradiction in Terms?," ACM HOTNETS IV, 2005. [PDF]

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