c-through: Part-time Optics in Data Centers

Transcription

1 Data Center Network Architecture c-through: Part-time Optics in Data Centers Guohui Wang 1, T. S. Eugene Ng 1, David G. Andersen 2, Michael Kaminsky 3, Konstantina Papagiannaki 3, Michael Kozuch 3, Michael Ryan 3 1 Rice University, 2 Carnegie Mellon University, 3 Intel Labs Pittsburgh Presented by Nadia Tkach

2 Outline Data Center Networks Overview Challenges & Existing Approaches Electrical vs Optical Switched Networks Helios c-through Approach & Design Traffic Demand Estimation, Traffic Batching, Traffic De-multiplexing Evaluation

3 Data Center Networks Conventional Tree VL2 Fat-Tree

4 Challenges Routing Massive amount of traffic Bursty traffic Congestion Cost of setup and maintenance Hardware and wiring costs Heat and power consumption

5 Current Solutions Spanning tree protocol Link layer routing protocols Partition-based approaches that split network into separate LANs

6 Flyways To De-Congest Data Center Networks Use of short wired and wireless links ( flyways ) and commodity switches to augment the network and selectively add capacity where needed Short range ~1 10 meters, high bandwidth ~1Gbps Improves performance only of a slightly oversubscribed networks

7 A Scalable, Commodity Data Center Network Architecture High bisection bandwidth using commodity Ethernet switches Based on Fat-Tree network topology Multi-path routing, load splitting across a number of commodity switches Link layer 2 switching and layer 3 routing

8 Packet Switching: Electrical vs. Optical Electrical Switching Full bisection bandwidth at packet granularity Optical Switching High bandwidth Time to reconfigure circuits ~ 1 20ms Reconfiguration causes high dynamism on the network (link ups/downs)

9 Helios: A Hybrid Electrical/Optical Switch Architecture for Modular Data Centers Hybrid approach between electrical and optical switched networks Implements traffic estimation and demultiplexing at the optical switch

10 Helios: A Hybrid Electrical/Optical Switch Architecture for Modular Data Centers Circuit Switch Manager unmodified circuit switch control software Pod Switch Manager initializes pod switch hardware, manage flow table, interface with TM Topology Manager monitor traffic patterns, estimate interpod traffic demands, calculate new circuit configurations

11 Helios: A Hybrid Electrical/Optical Switch Architecture for Modular Data Centers Benefits: Transparent to end-hosts Downfalls: Requires changes to the switches Pod switch can t split traffic over both packet and circuit switched ports for the traffic going to the same destination

12 c-through: Part-time Optics in Data Centers Hybrid Packet and Circuit (HyPaC) switched architecture High speed and low complexity Rack-to-rack optical circuit switched network Traffic estimation and de-multiplexing at the end-hosts

13 c-through: Design Connection between racks (multiple servers per rack) One high-bandwidth connection per rack to one other rack (one-to-one)

14 Traffic De-multiplexing 2 LANs separate electrical switched network from optical switched network Top-of-Rack (ToR) switches belong to both LANs Optically connected destinations have higher priority

15 Traffic Demand Estimation & Traffic Batching Implemented at the end-host Estimates traffic demand by increasing the perconnection socket buffer sizes Monitors the occupancy of buffers at run-time and optimizes the use of circuit Queued on a per-flow basis, thus avoids head-of-line blocking

16 Optical Circuit Configuration Central manager at the optical switch Maximum weight perfect matching with Edmond s algorithm

17 c-through: Evaluation [1] TCP adapts to the topology changes rapidly Batches traffic until the high bandwidth link is available

18 c-through: Evaluation [2] VM migration (bulk data transfer): near-optimal performance MapReduce (loose synchronization): coupling with electrical network provides near-optimal performance MPI Fast Fourier Transforms (tight synchronization): hard to saturate the optical network

19 c-through: Evaluation [3] Benefits Reduce load, improve throughput, reduce congestion Improve performance for bulk data transfer, skewed traffic pattern, loose synchronization Downfalls Potential increase in configuration complexity Moderate memory consumption (up to 100MB)