CPSC 601.43 Topics in Multimedia Networking A Mechanism for Equitable Bandwidth Allocation under QoS and Budget Constraints D. Sivakumar IBM Almaden Research

CPSC 601.43 Topics in Multimedia Networking

A Mechanism for Equitable Bandwidth Allocation

under QoS and Budget Constraints

D. Sivakumar

IBM Almaden Research Center

Sreenivas Gollapudi

Oracle Corporation /SUNY at Buffalo

The Twelfth IEEE International Workshop on Quality of Service IWQoS, 2004.

Presented by:Abdul Hasib



• Quality of Service (QoS)– Integrated Service– Differentiated Service

• Objective and previous work• Desired Properties• Basic principle • Bandwidth allocation algorithm• Comparison parameter• Experimental Results

Presentation outline


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).


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


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.


Int-serv (cont.)

• Two services level– guaranteed (delay) service, controlled load service.


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


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.

IngressEdge Router

EgressEdge Router

Interior Router


Router Functionality

• Interior routers: traffic classification and forwarding use DSCP as index into forwarding table

• 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.


Router Functionality (cont.)

Classifier MarkerShaper/Dropper

Meter

Traffic conditioning

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

PHB group

dataPHB class

real-timePHB class

PHB 11

PHB 22

PHB 21

low delay

highimportance

high delay

lowimportance


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.


• Quality of Service (QoS)– Integrated Service– Differentiated Service

• Objective and previous work• Desired Properties• Basic principle • Bandwidth allocation algorithm• Comparison parameter• Experimental Results

Presentation outline


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.


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.

iia B


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.

b


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

iu (b) : [0,B] 0

*

1

: minimum acceptable bandwidth;

: optimal bandwidth;

: maximum acceptable bandwidth

i

i

i

i ic (l, b) = l b,

iil B C


Utility function

, ( ) ( ) ( , )i i i iwelfare w b u b c l b


Bandwidth allocation algorithm (M)


Bandwidth allocation algorithm (M) (cont.)


Bandwidth allocation algorithm (M) (cont.)


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

*

**

00i

il


Fairness rank vs. QoS


Fairness rank vs. Probability of allocation


Thank you

Documents

CPSC 601.43 Topics in Multimedia Networking A Mechanism for Equitable Bandwidth Allocation under QoS and Budget Constraints D. Sivakumar IBM Almaden Research