Using Prices to Allocate Resources at Access Points

1
Using Prices to Allocate Resources at Access
Points

• Jimmy Shih, Randy Katz, Anthony Joseph

Access Point A
Network Resources
One Administrative Domain
Access Point B
User A
User B
2
Problem Statement

• We can solve congestion at access points by
  adding capacity, performing admission control,
  balancing loads between the access points,
  allowing advance reservation or constraining
  usage.
• We plan to explore
• How effective prices can affect users behaviors
  when used for admission control and load
  balancing at the access points.
• How to design resource allocation schemes to
  minimize the adverse effects of pricing. E.g
  instability, overhead.

3
State of the Art on Congestion Pricing

• Prior theoretical simulation work suggest that
  congestion pricing can
• Allocate resources to those who value them the
  most.
• Provide users with incentives to adjust their
  behaviors instead of constraining them.
• However, congestion pricing can also
• Cause users to experience unpredictable cost and
  performance.
• Require system overhead like accounting.

4
Key Concepts

• Perform congestion pricing at the application
  layer gt Only need to provide users with a web
  interface containing the current prices.
• Perform congestion pricing at the access points
  gt Only need to modify the access points.
• Use congestion pricing for admission control when
  users are willing to wait for resources or adjust
  their usage while using them.
• Use congestion pricing for load balancing when
  some access points are clearly better than
  others.

5
Using Prices to Allocate Resources at a H.323
Gateway
Possible User Web Interface

• Use prices for admission control and load
  balancing on connection oriented streams.
• Use prices to allocate the bottleneck resource,
  the number of phone lines at the gateway.
• Use prices to encourage users to use their
  computers instead of telephones to minimize using
  the bottleneck resource.

Current Price for Using Your Computer 10
Tokens/min
Next Minute Price for Using Your Computer 20
Tokens/min
Current Price for Using Your Telephone 15
Tokens/min
Next Minute Price for Using Your Telephone 35
Tokens/min
Packet Loss Rate When Using Your Computer 3
Handoff the Current Call to Your Telephone
[phone] Yes?
H.323 Gateway
PSTN
Internet
Handoff the Current Call to Your Computer
center.cs.berkeley.edu Yes?
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Using Prices to Allocate Bandwidth at an Access
Router

• Use prices for admission control on
  connectionless resources.
• Use prices to decide whose incoming and outgoing
  packets to drop during congestion.
• Inform users the amount of bandwidth they are
  using and allow them to reserve the amount they
  need.

Possible User Web Interface
Current Price Per Mbyte Per Sec 10 Tokens
Tokens Left for Today 200 Tokens
Current Usage 4 Mbyte Per Sec
How Much Bandwidth to Purchase 3 Mbyte Per
Sec
Users in a Local Area Network
Access Router
Internet
Most Willing to Pay Per Mbyte Per Sec 30 Tokens
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Accomplishments

• Design the appropriate policies for using
  congestion pricing at a H.323 gateway and at an
  access router.
• Fall of 1999 - Alpha testing of using congestion
  pricing at a H.323 gateway with users in our
  research group.
• Spring of 2000 Beta testing of using congestion
  pricing at a H.323 gateway with 50 users in the
  EECS department.

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Plans for Success

• Simulations
• Estimate the potential benefits and harms of
  using congestion pricing versus a first come
  first serve policy.
• Simulate when users are not sensitive to changing
  prices or require long times to react to changing
  prices.
• Use calling patterns from the H.323 gateways
  Beta testing.
• Use IP traces from the Internet Traffic Archive.
• Deployments
• In August, provide students in the UC Berkeley
  dorms with a H.323 gateway service that uses
  congestion pricing.
• In the fall, replace our research groups subnet
  router with a Nortel Java Programmable router
  that performs congestion pricing.

9
Summary and Conclusion

• See if congestion pricing really works in
  practice.
• Explore the right policies for using congestion
  pricing. E.g. how to ensure price system
  stability, minimize starvation, prevent denial of
  service attacks, etc.
• Explore the economic issues of using prices. E.g.
  amount of incentives required for users to choose
  congestion pricing over flat rate pricing, to use
  their computers instead of telephones, etc.