1 / 24

Adaptive Packet Marking for Providing Differentiated Services in the Internet

This paper discusses the use of adaptive packet marking to provide differentiated services in the internet. It explores the advantages and disadvantages of different QoS approaches, such as RSVP and IntServ, and presents the concept of Differential Services. The paper also introduces the Adaptive Packet Marking architecture and its mechanisms for providing soft bandwidth assurances without the need for end-to-end signaling.

coreyscott
Download Presentation

Adaptive Packet Marking for Providing Differentiated Services in the Internet

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. Adaptive Packet Marking for Providing Differentiated Services in the Internet Wu-chang Feng, Debanjan Saha, Dilip Kandlur, Kang Shin October 13, 1998

  2. QoS and the Internet • RSVP: signaling protocol for resource reservation • IntServ: services provided to applications • Advantages: • Per-flow end-to-end guarantees to applications • Disadvantages • Overheads • Control-path: per-flow signaling and state • Data-path: per-flow packet handling • Complexity • ISPs and deployment

  3. Differential Services • Provide service levels based on priority marking of packets • DiffServ WG • Advantages • No per-flow overheads • Deployment simple • Disadvantages • Difficulty in providing end-to-end per-flow guarantees

  4. Current Status • EF - Expedited Forwarding • Low loss, low delay forwarding behavior • Used to implement a virtual leased line service • AF - Assured Forwarding • Low loss forwarding behavior • Used to implement assured bandwidth service • Current EF/AF Services • Service models require end-to-end signaling and/or connection setup • Control path overhead • Service agreements bilateral, not end-to-end

  5. This work • Provide an architecture and mechanisms for using AF to provide soft bandwidth assurances • No end-to-end signaling • Rely on adaptation on the edges

  6. Adaptive Packet Marking • Per-flow or per-aggregate bandwidth requirement • Adaptively mark packets at edges until desired level is obtained • Marking at the source or in the network • Re-marking at boundaries to support service level agreements • Priority-aware queuing in routers (ERED)

  7. Packet Marking Architecture Legacy routers Re-marking to support SLAs Source Marking Marking Gateways ISP ToS enabled routers (ERED)

  8. Advantages • ISP deployment • Simple augmentation of SLAs to include additional priority • No end-to-end signaling • Service model (soft guarantees) allows for incremental deployment

  9. Packet Marking Gateway (PMG) • Increase marking probability if below target • Decrease marking probability if above target • Change conservatively to prevent bursts • Implemented and simulated in ns

  10. PMG Example • Aggregate with 6 Mbs target (up to 3 sources) • Other sources best-effort (up to 4 sources) • 10 Mbs bottleneck link

  11. PMG and Bandwidth Sharing • One 3 Mbs connection, five best-effort sources • Ideally: Target = Priority + Best-effort share • Problem: Excess marking

  12. Problems with PMG • Excess marking • Impacts pricing of services • Impacts ERED performance • Limits bandwidth sharing between connections

  13. Source Integrated Marking • TCP cognizant of packet marking • Two separate windows • priority window (pwnd) • best-effort window (bwnd) • Grow and shrink according to TCP dynamics • Provides bandwidth sharing with an optimal (minimal) amount of marking

  14. Source Integrated Marking

  15. Deployment Considerations • Non-responsive flows • Protection against malicious flows • Reduce marking to zero • Provides a disincentive for being malicious • Heterogeneity • Detect lack of service differentiation • Back-off marking and windowing • Over-subscription • Fall back on TCP sharing • Use of additional priority bits and/or queues

  16. Non-responsive Flows • All packets counted towards target • Incentive to send deliverable packets • Experiment with PMG • One 7 Mbs aggregate with 4 connections • One 3 Mbs aggregate with non-responsive flow

  17. Non-responsive Flows • PMG reduces marking to 0 Mbs • Problem: Flow consumes all best-effort bandwidth

  18. Non-responsive Flows • Use “Fair” ERED • Allocates best-effort bandwidth equally

  19. Heterogeneity • Legacy hardware and routers • PMG • No changes to end-host • Marking ignored • No clean way to turn off marking • Source-integrated • Connection treated as two separate connections • Potentially twice as aggressive • Turn off packet marking and windowing • Use inter-drop times (in packets) • Exponential back-off mechanism

  20. Heterogeneity • 4 best-effort sources over legacy 10 Mbs link • 1 source with 4 Mbs target rate

  21. Heterogeneity • Detecting network changes 4Mbs 4Mbs n0 n2 n3 BE n1 4Mbs 4Mbs n0 n2 n3 n1 BE BE ERED Drop-tail

  22. Over-subscription • PMG: End-host • Source-Integrated: • Windowing independent of target rate • Two 10 Mbs connections • Two 5 Mbs connections • 10 Mbs bottleneck

  23. Over-subscription • Additional priority bits and/or queues • Same experiment with CBQ • 70% Class A, 30% Class B

  24. Conclusion • Per-flow quality of service without per-flow overheads • Priority schemes in conjunction with intelligent control mechanisms at the edges • Low overhead • Ease of deployment • More information and related work • http://www.eecs.umich.edu/~wuchang/

More Related