QoS research in a complicated world

1. QoS research in a complicated world Christian HuitemaArchitect Windows Networking & CommunicationsMicrosoft Corporation

2. The state of research ? • We need QoS for VoIP, video on demand, etc. • To implement QoS, we need queuing models, signaling protocols, QoS contracts, etc. • And I get to do tons of maths and publish papers. QoS research in a complex world

3. The contrarian's view • Look at the real network! • We don’t really need QoS for VoIP, we need bandwidth for video on demand, etc. • QoS signaling is dead. • Maths are nice, use them for adaptivity. QoS research in a complex world

4. Myth : QoS provides better service • Myth: • In a QoS enabled network, you get more bandwidth, less delays • Reality: • QoS = access control. • You can only provide better service to some if you exclude others. • Deployment issue: • Only develop an application, if there is enough bandwidth “in most places” QoS research in a complex world

5. Myth: Applications will require QoS • Myth: • Applications will use a QoS API, because that will give better service. • Reality • As long as QoS is not ubiquitous, applications must be adaptive. • Deployment issue • Since applications don’t require it, little incentive to upgrade the network. • Little incentive to maintain the API QoS research in a complex world

6. Myth: congestion occurs in the network • Myth: • There are bottlenecks in the network, each hop adds delays • Reality: • Look at Global Crossing, Qwest, Worldcom • Price of Mbps divided by 6 in 2 years • Congestion occurs mostly at the edges. • Deployment issue: • Operators of large networks don’t perceive any benefit to QoS, just costs. QoS research in a complex world

7. Myth: QoS mechanism provide quality • Myth: • We can use QoS mechanisms to protect users from network issues • Reality: • How exactly do we use QoS to protect a web server against a denial of service attack? • Deployment issue: • Making the network more robust requires “last mile” solutions. QoS research in a complex world

8. Myth: eventually, QoS everywhere • Myth: • Eventually, all routers will provide QoS • Reality: • “Wireless guarantee” is an oxymoron • Deployment issue: • A broken QoS promise will break the application. • If you cannot have QoS everywhere, the application must be adaptive QoS research in a complex world

9. A short summary The difference between theory and practice is even larger in practice than in theory QoS research in a complex world

10. Three QoS research suggestions • Apply local solutions to local problems • Get more data • If you don’t have guarantee, adapt! QoS research in a complex world

11. Suggestion: research edge solutions • Backbone = large, edge = small • The law of big numbers does not apply to small numbers • Edge = degrees of liberty for innovation • MAC layer for wireless (802.1p ?) • Cooperation between local players • Receive side enforcement • First router solutions… • Liberty => research playground QoS research in a complex world

12. Suggestion: get as much data as we can! • Understand delays and losses • In the network, at the edges • What is the distribution? • What are the causes? • Fix the obvious bugs! • E.g. router hiccups, bad hardware • Repeat the measurements • Don’t settle for yesteryear data. • History matters! • Praise the XVI century astronomers! QoS research in a complex world

13. Today’s model are very crude The 1988 Internet 6 nodes NS simulations… TCP slow-start is probably wrong If we learn about the network, we can design better adaptation models Suggestion: research adaptation models APP Need the right black box model APP QoS research in a complex world

14. A short summary • Success is, finding something your professors don’t know • Even better, prove them wrong • Learn how the Internet really behaves, • Find where the old hypotheses are wrong, • Build on it! QoS research in a complex world