RNAP: A Resource Negotiation and Pricing Protocol Xin Wang

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RNAP A Resource Negotiation and Pricing Protocol

• Xin Wang, Henning Schulzrinne
• Columbia University
• xwang_at_ctr.columbia.edu, schulzrinne_at_cs.columbia.ed
  u
• (This work was supported by Hughes Research Lab)

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What is RNAP?

• Assumption network provides a choice of delivery
  services to user
• e.g. diff-serv, int-serv, best-effort, with
  different levels of QoS
• with a pricing structure (may be usage-sensitive)
  for each.
• RNAP a protocol through which the user and
  network (or two network domains) negotiate
  network delivery services.
• Network -gt User communicate availability of
  services price quotations and accumulated
  charges
• User -gt Network request/re-negotiate specific
  services for user flows.
• Underlying Mechanism combine network pricing
  with traffic engineering

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Outline

• Motivation
• Basic RNAP messaging
• Protocol details
• Architectures
• Scaling in Core Domains
• Advance reservation
• Pricing and charging
• Experimental Results
• Summary of Protocol Features
• Future work

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Motivation

• If multiple delivery service types are available,
  a flexible service selection and request
  mechanism is desirable.
• BBE services need pricing and charging support.
• Selecting and requesting a service at an
  agreed-upon price involves negotiation between
  user and network

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Motivation (Contd)

• Dynamic resource negotiation capability and
  congestion sensitive pricing are desirable
• Pricing signals congestion - allows safe and
  graceful QoS degradation OR increased spending to
  keep stable service
• Allows better resource utilization- dynamic
  re-negotiation allows higher utilization as
  resources need not be requested/provisioned
  conservatively
• Allows network resources to be obtained
  immediately - even during congestion (at high
  cost), e.g., urgent phone call
• Network can quickly recover from unexpected
  events - such as network failure by
  re-negotiating with users

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Typical Message Sequence
Query User enquires about available services,
prices
Query
Quotation
Quotation Network specifies services supported,
prices
Reserve
Reserve User requests service(s) for flow(s)
(Flow Id-Service-Price triplets)
Commit
Quotation
Commit Network admits the service request at a
specific price or denies it (Flow
Id-Service-Status-Price)
Periodic re-negotiation
Reserve
Commit
Close tears down negotiation session
Close
Release release the resources
Release
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Architecture-Centralized
(RNAP-C)
NRN
NRN
NRN
HRN
HRN
S1
R1
AD - B
AD - A
TD
Network Resource Negotiator
Internal Router
NRN
Edge Router
Host Resource Negotiator
HRN
Host
RNAP Messages
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Architecture-Centralized
(RNAP-C)
Query
NRN
NRN
NRN
HRN
HRN
S1
R1
AD - B
AD - A
TD
Network Resource Negotiator
Internal Router
NRN
Edge Router
Host Resource Negotiator
HRN
Host
RNAP Messages
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Architecture-Centralized
(RNAP-C)
Quotation
NRN
NRN
NRN
HRN
HRN
S1
R1
AD - B
AD - A
TD
Network Resource Negotiator
Internal Router
NRN
Edge Router
Host Resource Negotiator
HRN
Host
RNAP Messages
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Architecture-Centralized
(RNAP-C)
Reserve
NRN
NRN
NRN
HRN
HRN
S1
R1
AD - B
AD - A
TD
Network Resource Negotiator
Internal Router
NRN
Edge Router
Host Resource Negotiator
HRN
Host
RNAP Messages
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Architecture-Centralized
(RNAP-C)
Commit
NRN
NRN
NRN
HRN
HRN
S1
R1
AD - B
AD - A
TD
Network Resource Negotiator
Internal Router
NRN
Edge Router
Host Resource Negotiator
HRN
Host
RNAP Messages
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End-to-End Messaging

• Sender HRN sends Query to access NRN forwarded
  all the way to last-hop NRN
• Last-hop NRN builds and sends Quotation message
  upstream forwarded from NRN to NRN - quoted
  prices incremented at each NRN.
• Sender HRN sends Reserve message to access NRN
  forwarded downstream to to last-hop NRN
• Last-hop NRN builds and sends Commit message
  upstream forwarded from NRN to NRN - committed
  prices, accumulated charges incremented, or
  service request denied, at each NRN.

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Architecture - Distributed
(RNAP-D)
HRN
HRN
R1
AD - B
AD - A
TD
Internal Router
Edge Router
Host
RNAP Messages
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Architecture - Distributed
(RNAP-D)
HRN
HRN
R1
AD - B
AD - A
TD
Internal Router
Edge Router
Host
RNAP Messages
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Architecture - Distributed
(RNAP-D)
HRN
HRN
R1
AD - B
AD - A
TD
Internal Router
Edge Router
Host
RNAP Messages
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Scaling in Core Domains

• Direct Aggregation
• At boundary of access and core networks, map
  flow-level resource requests with same
  destination network to a single aggregate-level
  request.
• Inside core network, process aggregate RNAP
  messages only, tunnel flow-level RNAP messages.
• At edge of destination network, terminate
  aggregate-level RNAP message, re-activate
  flow-level RNAP messages.
• Aggregate RNAP sessions fewer in number, larger
  resource requests, longer negotiation interval -gt
  less overhead.

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Example Aggregation
50
50
100
100
50
50
NRN
NRN
NRN
150
150
HRN
HRN
100
100
HRN
AD - B
R2
AD - A
HRN
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Scaling in Core Domains (Contd)

• Block Negotiation
• Aggregate resources are added/given up in large
  blocks, to minimize negotiation overhead and
  reduce network dynamics

Bandwidth
time
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Advance Reservation

• Similar messaging sequence, reserve resources in
  advance for a specified future time
• Price can be different from immediate reservation
• Re-negotiation
• sell back or buy back
• Possible penalty or reward
• Useful for resource negotiation between domains

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Pricing and Charging

• How does the network arrive at a price?
• How will RNAP collect and communicate pricing and
  charging information?

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Price and Charge Formulation

• Router or NRN maintains state information
• Flow Id, negotiated price, charge for last
  negotiation interval, accumulated charge
• e2e price and charge collation
• negotiation message passing through router/NRN
  uses state information to increment price/charge
  fields
• Quotation message carry estimated price for each
  quoted service
• Commit message carry accumulated charge for
  preceding negotiation interval, committed price
  for next interval

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Price and Charge Formulation in a RNAP-C Domain

• Alternatives
• NRN does admission control and price computation
• forms price based on topology, routing and
  configuration policies, network load
• Ingress router does admission control and price
  computation
• may determine internal router loads through
  egress-to-ingress Probe messages
• Boundary and internal routers collect local
  prices/charges through intra-domain signaling
  protocol (YESSIR/RSVP).

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Example Price Formulation in RNAP-C
Table 2
Resource Table
Table 1
Domain Routing Table
ER1
R1
R1
ER2
NextHop
NextHop
(C, BW, Q, P)
(C, BW, Q, P)
Dest
1, 3, 30, 2
ER2
R1
ER2
ER1

R1
1, 2, 20, 1
Step1 determine a path (Table1)
C service class BW average bandwidth
(Mb) Q average queue length P price
(/Mb)
NRN
Step2 accumulate price along the
path (Table 2)
R1
ER2
ER1
Step 3 send total price ( 3/Mb )
R2
R3
TD
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Shared and Multicast Charging

• Senders and receivers can share the total cost
• Indicate willingness to pay by setting Charge
  Fraction field in Query/Reserve message
• Request is rejected if sum of Charge Fraction
  fields is lt1.

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Pricing Strategy

• Reservation_charge holding_charge
  usage_charge
  
  congestion_charge
• holding charge charge for reservation
• usage charge charge for resource consumption
• also dependent on service type, elasticity
• congestion charge charge for resource
  competition
• resource overbooking
• buffer overflow
• Long-term high price
• Resource re-provisioning (?)

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Testbed Setup
FreeBSD with routed, CBQ, RNAP
R1
S1
Rb
Ra
R2
S2
10 Mb
R3
S3
Embedded RNAP in RSVP Policy Data for prototype
RSVP
RNAP
Quotation
Path
Reserve
Resv
Commit
ResvErr
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Evolution of Network Price and Total Resource
Reservation
Total bandwidth 4Mb/s t1 total reservation
2Mb/s t4 total reservation 2Mb/s Targeted
bandwidth t2 total reservation 3Mb/s
t5 stabilized 70 (2.8 Mb)
t3 stabilized

2800
Total bandwidth reservation
Price
t1
t2
t4
t5
t3
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Throughput of Sessions Sharing Bandwidth
Fairness sharing of bandwidth for applications
with the same requirement and price sensitivity
S1
S2
S3
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Summary of Protocol Features

• A protocol that enables service negotiation
• multiple services, pricing, charging
• Supports centralized and distributed network
  architectures.
• Provides dynamic negotiation capability
• Periodic re-negotiation capability
• Flexible negotiation period
• User can disable/enable negotiation at any time

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Summary of Protocol Features (Contd)

• Pricing and charging capability
• Price and charge formulation, collation,
  communication to user
• Charging mode sender, receiver, or both
• Flexibility of service selection
• Multiple services int-serv, diff-serv,
  best-effort
• Different granularities of reservation flow,
  aggregate level
• Multi-party negotiation senders, receivers, both
• Stand alone, or embedded inside other protocols

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Summary of Protocol Features (Contd)

• Scalability
• independent of hop count aggregation in the core
  
• Price predictability
• Price is fixed for the service during a
  negotiation period
• Reliability
• Soft state for synchronous messages, liveness
  tracking
• Retransmission of asynchronous messages
• Server backup and information retrieval

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Future Work

• Complete implementation
• Large system performance evaluation