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)

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

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

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

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

6. Typical Message Sequence Query Quotation Reserve Commit Quotation Reserve Commit Close Release Query: User enquires about available services, prices Quotation: Network specifies services supported, prices Reserve: User requests service(s) for flow(s) (Flow Id-Service-Price triplets) Commit: Network admits the service request at a specific price or denies it (Flow Id-Service-Status-Price) Periodic re-negotiation Close: tears down negotiation session Release: release the resources

7. Centralized Architecture (RNAP-C) NRN S1 R1 NRN HRN Access Domain - B Access Domain - A Transit Domain Internal Router Edge Router Host RNAP Messages NRN HRN Network Resource Negotiator Host Resource Negotiator Intra domain messages Data

8. Architecture-Centralized NRN S1R1 Internal Router Edge Router Host RNAP Messages NRN HRN Network Resource Negotiator Host Resource Negotiator AD - B AD - A TD ( RNAP-C ) Query

9. Architecture-Centralized NRN S1R1 Internal Router Edge Router Host RNAP Messages NRN HRN Network Resource Negotiator Host Resource Negotiator AD - B AD - A TD ( RNAP-C ) Quotation

10. Architecture-Centralized NRN S1R1 Internal Router Edge Router Host RNAP Messages NRN HRN Network Resource Negotiator Host Resource Negotiator AD - B AD - A TD ( RNAP-C ) Reserve

11. Architecture-Centralized NRN S1R1 Internal Router Edge Router Host RNAP Messages NRN HRN Network Resource Negotiator Host Resource Negotiator AD - B AD - A TD ( RNAP-C ) Commit

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.

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

14. S1 R1 HRN Access Domain - B Access Domain - A Transit Domain Internal Router Edge Router Host RNAP Messages HRN Host Resource Negotiator Data Distributed Architecture (RNAP-D)

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

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.

17. NRN HRN R2 NRN HRN AD - B AD - A 50 100 50 100 150 50 100 150 50 100 Example: Aggregation

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

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

20. Pricing and Charging How does the network arrive at a price? How will RNAP collect and communicate pricing and charging information?

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

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).

23. Example: Price Formulation in RNAP-C NRN TD Dest NextHop ER1R1 NextHop ER2R1ER2 R1ER2 R1 1, 3, 30, 2 Domain Routing Table Resource Table ER1 ER2 R1 R2 R3 ER1 1, 2, 20, 1 ( C, BW, Q, P) Step1: determine a path (Table1) Step2: accumulate price along the path (Table 2) Table 1 Table 2 Step 3: send total price ( $3/Mb ) C: service class BW: average bandwidth (Mb) Q: average queue length P: price ($/Mb)

24. 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 <1.

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 (?)

26. Testbed Setup S1 S2 S3 R1 R2 R3 FreeBSD with routed, CBQ, RNAP 10 Mb Embedded RNAP in RSVP Policy Data for prototype Ra Rb QuotationPath ReserveResv CommitResvErr RNAP RSVP

27. Total bandwidth reservation Price t1t2t4t5t3 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 Evolution of Network Price and Total Resource Reservation

28. Fairness sharing of bandwidth for applications with the same requirement and price sensitivity S1 S2 S3 Throughput of Sessions Sharing Bandwidth

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

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

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

32. Future Work Complete implementation Large system performance evaluation