A Mechanism for Equitable Bandwidth Allocation under QoS and Budget Constraints

1. A Mechanism for Equitable Bandwidth Allocationunder QoS and Budget Constraints Sreenivas Gollapudi Oracle Corporation / SUNY at Buffalo D. Sivakumar IBM Almaden Research Center Presented by: Abdul Hasib CPSC 601.43 Topics in Multimedia Networking The Twelfth IEEE International Workshop on Quality of Service IWQoS, 2004.

2. Presentation outline • Quality of Service (QoS) • Integrated Service • Differentiated Service • Objective and previous work • Desired Properties • Basic principle • Bandwidth allocation algorithm • Comparison parameter • Experimental Results

3. Quality of Service (QoS) • Internet provides “Best effort” service • Simple • No admission control • No guarantee; no performance assurance • Single level of service • Not suitable for booming real time applications. The capability to provide resource assurance and service differentiation in a network is often referred to as quality of service (QoS).

4. Technologies • QoS parameters • Throughput; Delay; Jitter; Data corruption etc. • Developed technologies categorized by two key QoS issues: • Resource allocation • Integrated Service • Differentiated Service • Performance optimization • Multiprotocol label switching (MPLS) • Traffic engineering

5. Integrated Services (Int-serv) • Per-flow resource reservation. • Steps: • Application requests its required resource. • The network uses a routing protocol to find a path based on the requested resources. • Reservation protocol (RSVP) is used to install the reservation state along that path. • At each hop, admission control checks whether sufficient resources are available to accept the new reservation. • After reservation, the application can start to send traffic over the path for which it has exclusive use of the resources.

6. Int-serv (cont.) • Two services level • guaranteed (delay) service, controlled load service.

7. Int-serv (cont.) • Disadvantage: • Applicable to long lasting traffic (video conferencing); • Scalability problem • may not be able to cope with a very large number of flows at high speeds • requires the support of accounting and settlement between different service providers • Potential Application Area: • IP telephony, video conferencing over corporate intranets

8. Interior Router Egress Edge Router Ingress Edge Router Differentiated Service (Diff-serv) Uses a combination of edge policing, provisioning, and traffic prioritization to achieve service differentiation. • Resource allocation to aggregated traffic rather than individual flows. • Traffic policing on the edge and class-based forwarding in the core.

9. Router Functionality • Network edge routers: • Packet classification: service level agreement (SLA) and traffic type. • Responsible for mapping packets to their appropriate forwarding classes, per-hop behavior (PHB). Each PHB is represented by a 6 bit DSCP • Set DSCP in packet header DS field, modified TOS field. • Nonconforming traffic may be dropped, delayed, or marked with a different forwarding class. • Interior routers:traffic classification and forwarding •  use DSCP as index into forwarding table

10. Router Functionality (cont.) • Network edge routers: • traffic conditioning (policing, marking, dropping), SLA negotiation.

11. Diff-serv • Define forwarding behavior not end-to-end services. • Guarantee by provisioning rather than reservation: • For each forwarding class, the amount of traffic that users can inject into the network is limited at the edge of the network. • service providers can adjust the level of resource provisioning; • control the degree of resource assurance to the users. • Qualitative QoS scheme.

12. Presentation outline • Quality of Service (QoS) • Integrated Service • Differentiated Service • Objective and previous work • Desired Properties • Basic principle • Bandwidth allocation algorithm • Comparison parameter • Experimental Results

13. Objective and previous work • Fair and efficient bandwidth management. • Allocation based on differential pricing scheme. Previous work • Allocation is based on a single preferred bandwidth (A) request of user. • Uniform allocation rule: • Initially allocate an equal share (X) to every user, • if A<X, user will receive exactly A. • Excess bandwidth will be equally re-apportioned among all remaining users.

14. Desired properties • Feasibility: ; ai=allocated bandwidth to user i • Efficiency: • If the sum of ideal allocations exceeds the supply, then no user should receive more than his ideal allocation; • if supply exceeds the sum of ideal allocations, then no user should receive less than his ideal allocation. • Strategy proof ness: Mis-reporting bandwidth requirement should not give incentive to user. • Envy-freeness: When the allocations have been determined, no user would prefer other users allocation to his.

15. Basic principle • Network coordinator • is used to deploy the bandwidth allocation mechanism in a general network; • handles the functions of admission control. • Bandwidth allocation is based on: • Service provider (vendor) parameter • Cost function, c(b)= ; = constant • Capacity and utilization information of all links along path, P.

16. Basic principle (cont.) • Bandwidth allocation is based on: • User (agent) parameter: • Utility function, • Pricing level, li - User can choose to pay more for a QoS requirement to increase the likelihood of receiving the better service. - where, ci= cost function for agent I C= revenue goal

17. Utility function

18. Bandwidth allocation algorithm (M)

19. Bandwidth allocation algorithm (M) (cont.)

20. Bandwidth allocation algorithm (M) (cont.)

21. Comparison parameter (1) Quality of Service: For an agent with optimal allocation , an allocation b of bandwidth is defined to achieve a QoS value of Q( , b) = b/ (2) Probability of allocation: Fraction of agents who receive at least , their minimum acceptable allocation ( ). (3) Fairness rank, F(i) is proportional to

22. Fairness rank vs. QoS

23. Fairness rank vs. Probability of allocation

24. Thank you