Future Directions in QoS

1. Future Directions in QoS Engineering Internet QoS

2. Outline • Intserv over Diffserv • QoS Routing • Resource discovery and QoS • Virtual Private Network and QoS • Content Distribution Network and QoS • Billing and Charging for QoS Engineering Internet QoS

3. Intserv over Diffserv • Intserv: per-flow reservation using RSVP • Needs per-flow state management in core routers • Diffserv: Scalable but guarantees for aggregated flows Engineering Internet QoS

4. Comparison of Intserv and Diffserv Reprinted with Permission from “Engineering Internet QoS - Jha & Hassan, Artech House Publishing, Norwood, MA, USA. www.artechhouse.com Engineering Internet QoS

5. IS over DS architecture Reprinted with Permission from “Engineering Internet QoS - Jha & Hassan, Artech House Publishing, Norwood, MA, USA. www.artechhouse.com Engineering Internet QoS

6. QoS Mapping for IS over DS • Seamless IS over DS needs QoS mapping at the intersection of IS and DS • IS hosts : Controlled load or Guaranteed service • Invoked by individual flows • DS domain (core) doesn’t understand Intserv services • Understands EF/AF PHBs • Intserv services need to be mapped to Diffserv PHBs Engineering Internet QoS

7. Mappings continued • Guaranteed service may be mapped over EF PHB • EF capable of providing delay bounds required for GS • Controlled load can use either EF or AF PHB • No strict delay bound required Engineering Internet QoS

8. Point-Point communication in IS over DS • Sender generates RSVP PATH message describing its traffic profile; • The PATH message is processed (path state is installed) by all routers in the IS domain and it is forwarded to the DS domain toward the Receiver; • Routers in DS domain ignores the PATH message (no path state processing) and forwards it to the IS domain toward the Receiver; • Finally Receiver receives the PATH message and generates a RESV message Engineering Internet QoS

9. Point-Point communication in IS over DS • IS domain carries the RESV message toward the Sender; if any router has insufficient resources to support this reservation, it will generate an error message and will reject the request; • When the RESV message reaches Edge Router 1, it checks the Service Level Specification (SLS) of the DS interface to see if there is enough unused resources in the agreement to support this reservation request, if not the request is rejected, otherwise the RESV is forwarded toward the Sender; • Receipt of RESV message by Sender's RSVP process indicates that resource reservation has been successful. This Sender remains unaware of the fact that the core of the network does not support Intserv. Engineering Internet QoS

10. QoS Routing • Select routes that satisfy requested QoS for a connection • Global efficiency of router utilization • E.g., Shortest-widest path • Bandwidth as QoS metrics, selects paths with largest bottleneck bandwidth • Constraint based routing discussed in MPLS context Engineering Internet QoS

11. End-end QoS routing • Develop standards to be adopted across domains • Upgrade routers to support these standards • Higher processing, communication and storage overheads. • Currently restricted to Intranet environment Engineering Internet QoS

12. Resource discovery and QoS • A number of service providers in WAN • Clients need to discover these services • Who provides best service at a competitive price? • Resource discovery framework • Improved query responsiveness • Provide QoS capable service to end users • Mechanisms such as QoS routing and dynamic server load may be useful Engineering Internet QoS

13. Virtual Private Network and QoS • Legacy VPNS: leased lines or ATM/Frame Relay PVCs • Recent VPNs: IP based • Infrastructure cost savings • Ease of network management • How to provide QoS on shared IP-based VPN? • MPLS emerging as a candidate of choice. Engineering Internet QoS

14. Content Distribution Network and QoS • CDN: overlay network built to provide high-performance content delivery • Applications driving CDN network • Streaming-media, fashion parade, interactive video, e-commerce • May require performance guarantees from network Engineering Internet QoS

15. CDN contd • Techniques for performance improvement • Reduce number of hops • Strategically located cache server • Load balancing • Web-request redirection • Content provider’s site directed to data center of CDN • CDN directs request to a surrogate closest to the user (one that can provide better QoS) Engineering Internet QoS

16. Content Switches • Application layer switches • Higher layer information such as user capability, content type • Industry groups such as Content Alliance and Content Bridge working on standards • IETF WG Content delivery network peering (CDNP) • Interoperability between CDN providers Engineering Internet QoS

17. Billing and Charging • Common model: treat all packets equally • Charged for access only (dial-up links) • Other models: P = a * V + b * T + C • V: Volume downloaded • T: connection time • a,b,c: selected tariff • RADIUS/DIAMETER servers for authentication/accounting Engineering Internet QoS

18. Conclusion • Lots of progress made in last decade • Switches and routers with QoS features available in market • Last mile problem being solved with DSL, Cable modem … • Core upgraded with WDM … • Seamless QoS support over wired/wireless is still missing Engineering Internet QoS