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Microsoft Research

Microsoft Research. Shujaat Hussain. Cloud Faster!. Low latency web transactions. …. especially important to our key online properties. Common Cloud/Web Architecture. Proxy. DNS. HTTP Request to server. WAN. HTTP response from proxy. HTTP response from server. DNS Query.

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Microsoft Research

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  1. Microsoft Research Shujaat Hussain

  2. Cloud Faster! Low latency web transactions …. especially important to our key online properties

  3. Common Cloud/Web Architecture Proxy DNS HTTP Request to server WAN HTTP response from proxy HTTP response from server DNS Query MS Data Center DNS Response HTTP Request to Proxy

  4. Common Cloud/Web Architecture • Performance improvements possible on every leg on this figure • This architecture is used by many customers: internal and external • Speed up this, and everyone benefits Akamai Proxy Akamai/DNS HTTP Request to server WAN HTTP response from proxy HTTP response from server DNS Query MS Data Center HTTP Request to Proxy DNS Response

  5. Causes of delay • Poor user-to-proxy mapping • Delays in data center processing • Communication between Proxy and user • “last mile” • Several RTTs • Subject to loss and delay on last mile

  6. Data Center RTT = Y Akamai Proxy RTT = X CWND starts at 2 And opens slowly Total delay (if no loss): n* X + Y

  7. If there is packet loss .. • If SYN or SYN-ACK is lost • 3 second timeout • If data packet is lost, timeout is likely • Since window is small • Windows default minimum timeout is 300ms • Even if RTT to proxy is just 10ms!

  8. Proposed TCP Modifications • Modified TCP stack on proxy and Data Center nodes • Increase ICW • Bing search results are < 17K, compressed • ICW = 16 gets the page across in 1 RTT • Use historical data to determine which clients get increased ICW • Scale back in the presence of losses

  9. Data Center RTT = Y ECN Proxy RTT = X CWND starts at 16 Total delay (if no loss): 2 * X + Y

  10. To deal with last-mile loss • Proactively retransmit SYN-ACK a few times • If SYN-ACK is lost, client waits for 3 seconds before retransmit • Other critical packets can also be sent multiple times • Reduce MinRTO to 100ms • Large ICW itself increases chance of fast recovery

  11. Note … • All changes are on server • Compatible with all clients • Useful for any service that does short web transfers • Bing, Hotmail, Maps, Azure, … • Proxy Assisted or direct from data center • implemented and tested these changes

  12. Results Overview • Large ICW reduces median response time • Reduced latency tail due to • Aggressive retransmission of SYN-ACK • low minRTO • low initial RTO

  13. Cloud Cryptography New security challenges since cloud operators are expected to manipulate client data without necessarily being fully trusted. Microsoft is designing cryptographic primitives and protocols tailored to the setting of cloud computing, attempting to strike a balance between security, efficiency and functionality

  14. Applications/Scenarios Secure Outsourcing for Business Electronic Health Records Interactive Scientific Publishing Electronic discovery Regulatory compliance Geographic restrictions Subpoenas Data retention and destruction

  15. Searchable encryption Search documents without decrypting Backdoor key Tradeoff is Time and functionality Health data

  16. Azure Ocean — A Sea of Data in the Cloud The Ocean Observatories Initiative (OOI) is an NSF funded program to establish the ocean observing infrastructure of the 21st century benefiting research and education. The magnitude of the data from the cabled observatory, along with the complexity of scientific analysis and diverse user base, demands a cloud computing platform

  17. Other Research Areas ModisAzure — Azure Service for Remote Sensing Geoscience Bioinformatics Computation in the Cloud

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