RNAP: A Resource Negotiation and Pricing Protocol

1. RNAP: A Resource Negotiation and Pricing Protocol Xin Wang, Henning Schulzrinne Columbia University xwang@ctr.columbia.edu, schulzrinne@cs.columbia.edu (This work was supported by Hughes Research Lab) RNAP, X. Wang et al

2. 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 -> User: communicate availability of services; price quotations and accumulated charges • User -> Network: request/re-negotiate specific services for user flows. • Underlying Mechanism: combine network pricing with traffic engineering RNAP, X. Wang et al

3. 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 RNAP, X. Wang et al

4. 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 RNAP, X. Wang et al

5. Motivation (Cont’d) • 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 RNAP, X. Wang et al

6. 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 RNAP, X. Wang et al

7. 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 RNAP, X. Wang et al

8. 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 RNAP, X. Wang et al

9. 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 RNAP, X. Wang et al

10. 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 RNAP, X. Wang et al

11. 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 RNAP, X. Wang et al

12. 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. RNAP, X. Wang et al

13. Architecture - Distributed (RNAP-D) HRN HRN R1 AD - B AD - A TD Internal Router Edge Router Host RNAP Messages RNAP, X. Wang et al

14. Architecture - Distributed (RNAP-D) HRN HRN R1 AD - B AD - A TD Internal Router Edge Router Host RNAP Messages RNAP, X. Wang et al

15. Architecture - Distributed (RNAP-D) HRN HRN R1 AD - B AD - A TD Internal Router Edge Router Host RNAP Messages RNAP, X. Wang et al

16. 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 -> less overhead. RNAP, X. Wang et al

17. Example: Aggregation 50 50 100 100 50 50 NRN NRN NRN 150 150 HRN HRN 100 100 HRN AD - B R2 AD - A HRN RNAP, X. Wang et al

18. Scaling in Core Domains (Cont’d) • Block Negotiation • Aggregate resources are added/given up in large blocks, to minimize negotiation overhead and reduce network dynamics Bandwidth time RNAP, X. Wang et al

19. 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 RNAP, X. Wang et al

20. Pricing and Charging • How does the network arrive at a price? • How will RNAP collect and communicate pricing and charging information? RNAP, X. Wang et al

21. 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 RNAP, X. Wang et al

22. 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). RNAP, X. Wang et al

23. Example: Price Formulation in RNAP-C Table 2 Table 1 Resource Table 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 RNAP, X. Wang et al TD

24. Shared and Multicast Charging • Senders and receivers can share the total cost • Indicate willingness to pay by setting ChargeFraction field in Query/Reserve message • Request is rejected if sum of Charge Fraction fields is <1. RNAP, X. Wang et al

25. 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 (?) RNAP, X. Wang et al

26. 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 RNAP, X. Wang et al

27. 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 t3 t4 t5 RNAP, X. Wang et al

28. Throughput of Sessions Sharing Bandwidth Fairness sharing of bandwidth for applications with the same requirement and price sensitivity S1 S2 S3 RNAP, X. Wang et al

29. 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 RNAP, X. Wang et al

30. Summary of Protocol Features (Cont’d) • 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 RNAP, X. Wang et al

31. Summary of Protocol Features (Cont’d) • 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 RNAP, X. Wang et al

32. Future Work • Complete implementation • Large system performance evaluation RNAP, X. Wang et al