IMPLEMENTING A DYNAMIC PRICING SCHEME FOR QOS

ENABLED IPV6 NETWORKS

El-Bahlul Fgee, Shyamala Sivakumar

‡

, W.J. Phillips and W. Robertson, J. Kenny

Department of Engineering Mathematics, Dalhousie University, Halifax, Canada

‡Computing and Information Systems, Sobey School of Business, Saint Mary's University, Halifax

Keywords: IPv6 QoS manager, d

ynamic pricing.

Abstract: Currently the Internet based on IP supports a single best-effort service in which, all packets are queued and

forwarded with the same priority. No guarantees are made regarding timely and guaranteed delivery.

However, many e-commerce applications, that are delay and loss sensitive, use the Internet as a transport

infrastructure because of its reach-ability, and cost efficiency. Challenges faced by ISPs supporting e-

commerce traffic include enhancing their traffic flow handling capabilities, speeding the processing of these

packets at core routers, and incorporating Quality of Service (QoS) methods to differentiate between traffic

flows. These schemes add to infrastructure costs of network providers which can be recovered by

introducing extra charges for QoS enabled traffic. Many pricing schemes have been proposed for QoS-

enabled networks. However, integrated pricing and admission control has not been studied in detail. In this

paper a dynamic pricing model is integrated with an IPv6 QoS manager to study the effects of increasing

traffic flows rates on the increased cost of delivering high priority traffic flows. The pricing agent assigns

prices dynamically calculated according to the network status for each traffic flow accepted by the domain

QoS manager. Combining the pricing strategy with the QoS manager allows only higher priority traffic

packets that are willing to pay more to be processed during congestion. This approach is flexible and

scalable as pricing is decoupled from QoS decisions and reservations.

1 INTRODUCTION

Traditionally IPv4 incorporates simplistic pricing

approaches such as flat rate for unlimited usage and

is based on a fair distribution of costs. IPv6 supports

QoS by introducing the flow label field which

uniquely defines all the packets belonging to the

same flow. In IPv6 domains, a QoS manager can

take advantage of the flow label and traffic class

fields, to handle domain resources and to

differentiate traffic flows. This system is capable of

negotiating QoS parameters, upon accepting user

connection, that includes guaranteeing the quality.

Therefore, the resource for delay and loss sensitive

traffic is secured and these flows are processed faster

than other flows. Such differentiation makes pricing

an important, if not critical issue, in today's Internet.

In the future the issue of pricing will be more

relevant as more E-commerce applications begin to

rely on the Internet for their delivery (Faizuullah,

2000). Flat pricing is unfair as it does not

differentiate between traffic flows with differing

QoS requirements. Proposing appropriate pricing for

QoS-enabled networks is a challenging problem as

pricing must be integrated with admission control

strategies (Tianshu, 2004). Our IPv6 QoS manager

uses a combination of a packet’s flow ID and the

source address (Domain Global Identifier (DGI))

(Fgee, 2004), to process and reserve QoS inside a

domain. This QoS manger is integrated with a

dynamic pricing model (Tianshu, 2003) to study the

effects of increasing traffic rates on the increased

cost of delivering high priority traffic flows. The

pricing agent assigns prices for each traffic flow

initially accepted by the domain manager. Pricing is

dynamic and calculated based on network status.

Section 2 defines QoS and the parameters used to

easure it. Section 3 discusses the new elements of

IPv6 needed to enable QoS. Section 4 gives an

289

Fgee E., Sivakumar S., J. Phillips W., Robertson W. and Kenny J. (2005).

IMPLEMENTING A DYNAMIC PRICING SCHEME FOR QOS ENABLED IPV6 NETWORKS.

In Proceedings of the Seventh International Conference on Enterprise Information Systems - DISI, pages 289-292

 SciTePress

overview of the proposed IPv6 QoS manager (Fgee,

2004). Section 5 discusses how the dynamic pricing

model is integrated with the QoS manager.

Simulation results are presented to illustrate the

feasibility of the integrated approach.

2 QOS REQUIRMENTS

QoS is the ability of a network to provide better

services to selected network traffic over different

underlying technologies. End-to-end delay, jitter,

bandwidth and packet loss rate are the parameters

typically used for characterizing QoS of individual

connections or data flows (Jha, 2002). The elements

commonly involved in providing QoS guarantees are

(Jha, 2002): 1) Admission Control determines access

to available network resources and keeps track of all

reservations. 2) Policing is performed when a flow’s

actual data traffic exceeds the requested values given

in the traffic specifications. In such cases the packets

are dropped or downgraded to a best effort service

class or marked as non-conforming. 3) Packet

classification identifies packets belonging to a

specific flow and designates a QoS class for this

flow. 4) Packet scheduler ensures that the flows

identified by the packet classifier receive the

requested QoS. 5) Traffic control implementation

involves queuing methods employed to control

traffic at routers interfaces. Function 1) and 2) are

handled by the domain QoS manager. Functions 3)

and 4) are implemented at the edge points.

3 INTERNET PROTOCOL V6

Two components of IPv6 are used to deliver QoS,

the first is the 8-bit priority field in the IPv6 header

that can be used to identify and discriminate traffic

types based on contents of this field. The second

component is the flow label which is used to label

packets belonging to traffic flows for which the

sender requests special handling. Network elements

can now classify packets based on IP semantics

allowing for efficient mapping of packets to their

flows and hence to their flow specification policy.

The flow label is chosen by the IPv6 QoS manager

and is used for reserving resources, and routing and

monitoring traffic flow packets. Also, packets can

now be associated with particular service classes and

IPv6 routing performed on the basis of these classes,

thus improving the performance of core routers. The

benefits of this scheme (Fgee, 2004) are its

simplicity and speed.

4 IPV6 QOS MANAGEMENT

The proposed QoS scheme handles QoS requests by

processing, monitoring, and controlling the traffic

flows. Weighted Fair Queuing (WFQ) is used to

separate the flows in which separate queues are

assigned for each traffic flow. The IPv6 QoS

management system uses the DGI and traffic class

(TC) field for reserving and tracking traffic flows.

This scheme is unique in that the IPv6 network can

be managed without invoking any other QoS

protocols such as RSVP or MPLS. The end-to-end

delay is less as the backbone routers use the DGI for

forwarding decisions as compared to the longest

match procedure used by other schemes. This

technique is scalable as the edge routers handle QoS

requests and communicate with other QoS

managers. Traffic flows are classified based on the

TC field so that each priority level is treated

differently. A sender sends its QoS request to the

network edge router. Upon receiving requests, the

edge router communicates with its domain manager

to approve or reject these requests. The edge router

forwards the manager’s responses, either positive or

negative, to the sender. When accepted, the source

starts sending data packets to the edge router where

traffic flow packets are classified, scheduled and

monitored. Packets are queued depending on their

TC field and the policies set by the QoS manager.

The leaky bucket algorithm is implemented to police

incoming traffic. The algorithm parameters for the

accepted traffic are setup according to their traffic

specifications. When a flow violates its requested

specification, its priority level is degraded or its

packets dropped.

5 DYNAMIC PRICING MODEL

The pricing model is based on the DiffServ end-to-

end pricing scheme introduced in (Tianshu, 2003).

In this market based model the value for the base

price

and fill factor is set by the network

provider for each traffic type. The fill factor is the

ratio of target capacity

to the maximum capacity

for a service class i. The price for a

class i at time t is computed (Tianshu, 2003, Waog,

2001) by:

base

max

)(tP

iiiiii

TTDtPtP /)()1()( −

−

Here,

is the demand or current load for class i

and

is the convergence rate factor that determines

ICEIS 2005 - SOFTWARE AGENTS AND INTERNET COMPUTING

290

how the price converges to its maximum. Figure 1

illustrates the general pricing strategy. When the

load for a particular service class is lower than its

targeted capacity, the price is the base price

base

at particular service class. As the load exceeds

its target capacity, and when the load is close to the

maximum capacity, the price is increased rapidly i.e.

we have a dynamic pricing scheme where the price

is a function of current network conditions.

for th

Figure 1: General pricing strategy

During demand increase we adopt the exponential

pricing strategy.

⎪

⎭

⎪

⎬

⎫

⎪

⎩

⎪

⎨

⎧

≤

−

otherwiseeP

TDif

base

]1[

)(

A price limit,

, indicates the price when the

s m

max

demand reache aximum capacity is set for each

service class that and is given by:

]1[ −

max

base

ePP

Knowing

d the fill factor for a

ss i ves th ve

max

base

service cla gi e solution for the con rgence

factor

that determines how the price converges

to the m ximum. a

)

(*)log(

max

base

P −

The total revenue is the sum of all classes’ prices.

5.1 Pricing integrated QoS manager

Figure 2 shows the flow chart of the proposed

rou

6 SIMULATION RESULTS

We study the behavior of the integrated pricing

.04 pe

cenarios have been tested for each

pricing model. This figure summarizes the functions

performed by the various network entities in

implementing the pricing strategy. The source

initiates the QoS request and waits for responses that

include the acceptance messages and the associated

prices. The edge router forwards requests and

responses. It monitors all traffic packets entering the

domain. The IPv6 QoS manager processes the QoS

requests and then sends the network status for each

accepted traffic flow to the pricing agent. The

pricing agent calculates the price for each accepted

traffic flow by first finding

f using the

information received from the domain QoS manager

which includes the expected traffic rate (

T ) and the

max allowed rate (

). The pricing agent

attached to the edge ter initiates the price

according to the network status and the defined base

price (

base

) for each traffic class accepted by the

manager. Prices are sent to the customers that

initiated requests who accept or reject the prices.

max

model in an IPv6 QoS capable environment using

the ns-2 simulator (NS-2, 2004). Figure 3 illustrates

the network topology used in simulations and

consists of 4 core and 2 edge routers. The Ingress

router acts as the pricing agent and handles QoS

requests generated by source1 and source2 nodes.

The total capacity of each link is 1 Mpbs with a

propagation delay of 1 msec. The traffic flow

specifications are: Source 1 has a traffic rate of 500

Kbps with priority 15 and Flow ID-15. Source 2 has

a traffic rate of 250 Kbps with priority 12 and flow

ID 12. Source 3 has a traffic rate is 250 Kbps, is

classified as Best effort type with flow ID- 8. The

base prices

base

for each class is set at $0.16,

$0.09 and $0 r unit time respectively starting

with the flow with the highest priority. Simulation

was performed on three flows with FID-15 having

the highest priority when the total link capacity

reaches 50%, FID-12 has the 2

highest priority

when the total link capacity reaches 70% and FID-8

is classified as Best Effort for all link capacities

(Tianshu, 2003).

Two simulation s

traffic flow, one when the total link load is less than

the percentage assigned for each flow and the other

one when the traffic exceeds these percentages.

Figure 4 shows the change of the prices for traffic

flow FID-15.

IMPLEMENTING A DYNAMIC PRICING SCHEME FOR QOS ENABLED IPV6 NETWORKS

291

Figure 2: Flow chart for the IPv6 pricing model

Figure 3: Simulated pricing model network

Figure 4: Prices for the three traffic flows FID(15) &

FID(12) and FID(8)

From Figure 4 it is seen that the prices change

rapidly as the load increases which results in more

revenue. We see that the changes in the prices for

traffic flows FID-12 does not change much since its

percentage is set to 70% and the packets of this flow

are not as critical as the first one. This also results in

a small increase in the revenue compared with the

first one. However, during congestion packets

belonging to FID-12 are degraded to best effort as

per the policies set by the QoS manager. Best Effort

flow packets have no change in prices since the

expected load is set to 100%, however, they are the

first to be dropped during congestion.

Source

1-Send QoS request

2- Check price &

resource availability

3- Send data &

disconnect

IPv6 QoS Manager

1-Receive QoS requests

2-Sends responses to

requests

3-Provides network stats

used to calculate prices

4- Calculate weights used to

define

per flow

max

Edge Router

1- Receive/forward QoS

request

2- Classify, schedule

incoming traffic

3- Monitor incoming traffic

4- Communicate with

domain

ricin

ent

7 CONCLUSION

Pricing Agent

1- Calculate

C , .

max

2- Updates prices

3- Calculate domain

revenue

The main objective in IP billing schemes is to price

network resources dynamically, especially during

congestion. In this paper, an IPv6 QoS manager was

integrated with a DiffServ dynamic pricing model.

The manager allows only higher priority traffic

packets that are willing to pay more to be processed

during congestion. In this approach the pricing is

decoupled from QoS decisions/reservations thus

avoiding per-flow based messaging for either pricing

or admission control. In addition to the scalability

and simplicity, more revenues are generated as

prices change dynamically according to the network

status.

REFERENCES

Fgee, E., Kenney J., Phillips, W.I., Robertson, W.,

Sivakumar, S., “Implementing an IPv6 QoS

management scheme using flow label & class of

service fields”, IEEE CCECE 2004. vol 2 , pp.851- 54.

S. Faizuullah and Marsic, I, “

Pricing QoS: Simulation and

Analysis”,

Proceedings. 34th Annual Simulation

Symposium, 2001, Pp 193-199.

Tianshu Li, Y. Iraqi and R. Boutaba, “Pricing and

admission control for QoS-enabled Internet",

Computer Networks, 2004 Published by Elsevier.

S. Jha and M. Hassen, “Engineering Internet QoS”, Artec

House Boston, London 2002.

Tianshu Li, Y. Iraqi and R. Boutaba, "Traffic-Based

Pricing and Admission Control for DiffServ

Networks", Integrated Network Management, 2003.

IFIP/IEEE 8

Intl. Symposium, pp. 73-86.

X. Waog and H. Schulzrine, "Pricing Network Resource

for Adaptive Applications in a Differentiated Service

Network", INFOCOM 2001., Vol 2 , Pp: 943 – 952.

NS-2 The Network Simulator ns-2, Oct. 30, 2004.

http://www.isi.edu/nsnam/ns/.

ICEIS 2005 - SOFTWARE AGENTS AND INTERNET COMPUTING

292