1 / 18

SPAIN: Multipath Forwarding For COTS Ethernet

tracey
Download Presentation

SPAIN: Multipath Forwarding For COTS Ethernet

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Presenter: Praveen Yalagandula, HP Labs, Palo Alto Collaborators: Jayaram Mudigonda & Jeff Mogul, HP Labs Mohammad Al-Fares, UCSD SPAIN: Multipath Forwarding For COTS Ethernet

    2. OC Testbed Shuffle Experiment 2 29 May 2012 Shuffle experiment with about 80 servers Approximate Map-Reduce or a large join 500 MB transfer from every node to all other nodes At most 5 simultaneous transfers at a time

    3. Utilization 3 29 May 2012

    4. OC Testbed Shuffle Experiment 4 29 May 2012 Shuffle experiment with about 80 servers Approximate Map-Reduce or a large join 500 MB transfer from every node to all other nodes At most 5 simultaneous transfers at a time

    5. Goal Scalable, cheap, high-performance L2 datacenter networks Why L2? Cheaper switches (vs. L3 routers) Less configuration required Flat addressing makes VM migration much easier 29 May 2012 5

    6. What about Ethernet? Ethernet is (mostly) wonderful: COTS technology Increasingly high bandwidth Self-configuring with Spanning Tree Protocol (STP) Avoids packet-forwarding loops But: Spanning Tree creates problems: Only links within the spanning tree are actually used Limits bisection BW and flexibility in node placement Forces the use of expensive core switches 29 May 2012 6

    7. SPAIN: Smart Path Assignment In Networks Multipath forwarding Exploits all physical links, not just spanning tree Over arbitrary topologies does not require fat-tree, hypercube, etc. Uses unmodified, COTS Ethernet switches as long as they have VLAN support 29 May 2012 7

    8. Other approaches Designs requiring specific, regular topologies PortLand, VL2, DCell, BCube Designs focusing on shortest-path but not multipath TRILL, SmartBridge, SEATTLE Also require changes to switches (HW/SW/Both) SPAIN is unique because it supports multiple paths between nodes in arbitrary topologies, uses unmodified COTS switches, and is incrementally deployable 29 May 2012 8

    9. SPAIN in one slide Central, off-line manager: Discovers network topology Pre-computes a set of paths that best exploit the redundancy of the physical network links Merge paths into a minimal set of trees Map trees onto VLANs and install these into switches End-host modifications: Download mapping table from manager Classify packets into flows (e.g., TCP connections) Choose correct VLAN for new outgoing flows “Chirping” protocol for efficient fault detection (etc.) Table maintenance on packet transmission/reception 29 May 2012 9

    10. SPAIN in Action 10 29 May 2012

    11. 11 What paths to use? Goal: Utilize the topological redundancy well Challenge: Network graphs can be extremely huge Approach: Trim the graphs, use link-disjoint paths greedily How to map paths to VLANs? Goal: Maximize the number of installed paths Challenge: Limited switch resources; only 4096 VLANs Approach: Graph-coloring based algorithms What should the end-point do? Goal: Balance load well Challenge: Limited view of the network Approach: Pick a VLAN randomly (uniform/biased on path length) SPAIN needs to answer three questions 29 May 2012

    12. SPAIN: Simulations Considered different topologies Regular: Fat Trees Arbitrary: AS topologies from the RocketFuel project Up to 1600 switches, 13K links, 80K end hosts Compared SPAIN and Spanning Tree Metrics Path Set Quality: Link Coverage, (Potential) Reliability Feasibility: #VLANs required Effectiveness: Aggregate throughput With a large number of flows (up to 10Million) 12 29 May 2012

    13. SPAIN: Simulation Results Link Coverage: SPAIN: 100% in all cases considered Spanning Tree: varied from 2% to 51% Reliability: With a link failure probability of 0.04 Spanning Tree: prob. of path failure varies from 0.16 to 0.45 SPAIN: prob. of path failure varies from 0.00 to 0.04 Feasibility: #VLANs required is less than 4K for all topologies except one case Aggregate Throughput: Arbitrary topologies: 0.67X to 10X improvement over Spanning Tree Fat tree: 24X improvement over Spanning Tree 13 29 May 2012

    14. SPAIN OpenCirrus testbed 29 May 2012 14

    15. SPAIN: Prototype experiments Quick-and-dirty Linux implementation Adds lots of unnecessary overhead; we know how to fix it Deployed and tested on OpenCirrus testbed 80 hosts dispersed across 3 racks/3 switches Shuffle experiment (similar to Map-Reduce or large join) 500 MB transfer from every node to all other nodes At most 5 simultaneous transfers at a time Results: Improvements limited by software and servers, not by SPAIN design 30% improvement in the aggregate throughput 22% reduction in the mean completion time Demonstrated incremental deployability of SPAIN Demonstrated fault-tolerance capability of SPAIN 29 May 2012 15

    16. SPAIN on OpenCirrus Shuffle Experiment 29 May 2012 16 Photo of OpenCirrus? Animation of the dataPhoto of OpenCirrus? Animation of the data

    17. Incremental deployability 29 May 2012 17

    18. Next Steps Open SPAIN enhancements for other users of the test bed OpenCirrus topology planned enhancements A two-level Fat-Tree + Mesh topology Connect all 8 racks at HP Labs No over-subscription (full bisection bw) 18 29 May 2012

    19. Questions? ”SPAIN: COTS Data-Center Ethernet for Multipathing over Arbitrary Topologies” Jayaram Mudigonda and Praveen Yalagandula, HP Labs; Mohammad Al-Fares, UCSD; Jeffrey C. Mogul, HP Labs To appear at NSDI 2010, San Jose, CA 29 May 2012 19

More Related