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

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

Documents

service differentiation

multimedia networking

quality of service iwqos

controlled load service

multimedia networking

service level agreement

best effort service

traffic classification