hastin
Uploaded by
14 SLIDES
260 VUES
140LIKES

Implementing Quality of Service (QoS) in Networking: Mechanisms and Considerations

DESCRIPTION

This document outlines the fundamental concepts and mechanisms of Quality of Service (QoS) as explored by Jean Walrand. Key aspects include bandwidth, delay, and the distinction between edge-to-edge and end-to-end QoS approaches. It discusses implementation mechanisms such as access control, packet marking, and incentive-compatible protocols. Additionally, the document examines various pricing models, including flat fees and congestion-based pricing. The importance of throughput, latency, and security in measuring QoS performance is also highlighted.

1 / 14

Télécharger la présentation

Implementing Quality of Service (QoS) in Networking: Mechanisms and Considerations

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. Implementing QoS Jean WalrandEECS

  2. Outline • What? • Bandwidth, Delay • Where? • End-to-End, Edge-to-Edge, Edge-to-End, Overlay • Mechanisms • Access Control • Packet Marking • Vegas • Incentive-Compatible Protocols • DiffServ, MPLS • Pricing • Flat, Usage, Congestion

  3. What? • Throughput: R Mbps • Flow: e.g., TCP connection • Pipe: e.g., (IP source, IP destination) • Possibly, class (e.g., VoIP) • Hose: Aggregate rate out of port • Timescale • 1 Mbps over every ms • 1 Mbps over every second

  4. What? (continued) • Latency: • Upper bound: T  Dmax[e.g., conference => Dmax 200ms] • Jitter: Tmax – Tmin Jitter [Playback buffer => CBR]

  5. What? (continued) • Other: • Security: e.g., VPN. Measure of security? [Physical: Fiber; Link: VLAN; IP: Ipsec; …] • Availability: e.g., except for 1 hour every 10 years … [MTBF, MTBR]

  6. Edge-to -edge Edge-to -edge End-to-end Where?

  7. Overlay Network = QoS box = edge-to-edge with QoS .. Where? (continued)

  8. Mechanisms • Access Control • Example: MAN R 1 Gbps (bi-dir) Police R to 1 Gbps/N => Guaranteed

  9. Mechanisms (continued) • Packet Marking (Frank Kelly) • Mark with probability that the extra packet creates a loss; • User pays per mark and slows down when pay rate reaches budget • Revenues = Loss rate (times unit cost) Distributed according to “willingness to pay” By choosing unit cost, adjust loss rate. Throughput is then divided according to user utilities. => Single class, but differentiated services.

  10. Mechanisms (continued) • Vegas + Window = rate x Prop + backlog Try to maintain a fixed backlog Equal backlogs => Equal throughputs (B. Davie) Extension to multiple bottleneck case (J. Mo) Difficulty: Not compatible with Reno

  11. Mechanisms (continued) • Incentive-Compatible Protocols • Problem: If QoS is free, users will ask for bestAs result, wasted resources • Solution?: Design protocols that discourage waste • Attempt: • Voice: Low delay, larger loss • Data: Larger delay, small loss • [E.g., differentiated RED with priority …] • Shortcoming: Can cheat with FEC for data

  12. Mechanisms (continued) • DiffServ • Typically three classes: • Expedited Forwarding (Low lagency, e.g., VoIP) • Assured Forwarding (Guaranteed rate) • Best Effort • MPLS • Typically long-term SLAs • Protection switching is possible • Traffic Engineering to “optimize” network

  13. Mechanisms (continued) • Proposal: • Overlay Network • Network domains implement AF or MPLS • QoS Boxes implement • Classification • Policing • Pricing • QoS Transport (e.g., Vegas +)

  14. Pricing • Flat Fee: $30.00/month • Pros: Simple, predictable, bounded • Cons: Wasteful (cannot provide 10Mbps on demand) • Usage-Based: $0.01/Mbyte • Pro: Encourages rational use • Cons: Unpredictable (can learn), risky (can cap), requires sophistication • Congestion-Based: time-of-day, spot price • Pro: Most rational, leads to best utilization • Cons: Sophisticated (requires software agents) • Mechanisms? • Heavy infrastructure necessary?

More Related