SIP Overload Control IETF Design Team Status

1. SIP Overload ControlIETF Design Team Status Volker Hilt volkerh@bell-labs.com Bell Labs/Alcatel-Lucent

2. SIP Overload Control Design Team • Team Members • Eric Noel, Carolyn Johnson (AT&T Labs) • Volker Hilt, Fangzhe Chang (Bell Labs/Alcatel-Lucent) • Charles Shen, Henning Schulzrinne (Columbia University) • Ahmed Abdelal, Tom Phelan (Sonus Networks) • Mary Barnes (Nortel) • Jonathan Rosenberg (Cisco) • Nick Stewart (British Telecom) • Four independent simulation tools • AT&T Labs, Bell Labs/Alcatel-Lucent, Columbia University, Sonus Networks • Bi-weekly conference calls.

3. draft-ietf-sipping-overload-design-01Changes to -00 • Added new sections on: • Fairness • Introduces fairness categories. • Performance Metrics • Discusses metrics to compare overload control mechanisms • Message Priorization • Selection of messages in overload condition. • Added text to Security Considerations section. • Minor edits throughout the text.

4. draft-ietf-sipping-overload-design-00Next Steps Discussion of overload control mechanisms needs to be structured along the identified performance metrics. Document is close to completion.

5. SIP Overload Control Design TeamSimulation Results Four types of overload control • Rate-based Overload Control • Loss-based Overload Control • Window-based Overload Control • Overload Signal-based Overload Control Summary of Steady-State Evaluation (presented at IETF ’73) • Performance of all overload control mechanisms under evaluation is similar in steady state. • Varying network conditions (i.e., delay, loss-rate) do not reveal significant differences. Results for Transient Scenarios • Evaluation of transient behavior with respect to • Changes in offered load • changes in the number of neighbors • Fairness

6. Changes in Offered-Load (AT&T Labs) Rate-based and Window-based Overload Control • Simulations use the following overload control feedback types and algorithms: • Rate-based: queue delay • Loss-based: SRED • Window-based • Feedback conveyed in SIP responses. • Result: rate-, loss- and window-based controls respond well to transient stimulus.

7. Changes in Offered-Load (Bell Labs/Alcatel-Lucent) Loss-based and Rate-based Overload Control CPS CPS Time Time • Overload control feedback type and algorithms used: • SRED algorithm • Loss- vs. rate-based feedback • SIP responses convey feedback from core to edge proxies. • Result: loss- and rate-based overload control perform well.

8. Changes in Offered-Load (Columbia University) Window-based and Rate-based Overload Control 2014/10/11 Slide 8 Window- and rate-based controls perform well.

9. Changes in Offered-Load (Sonus Networks) Loss-based and Overload-Signal-based Overload Control Target Overload Signal Rate =10 Overload Signals /Sec

10. Changes in the Number of Senders (Bell Labs/Alcatel-Lucent)Loss-based and Rate-based Overload Control • Edge proxies are turned on/off sequentially. • Each edge proxy sends the same amount of load while active. • Feedback-type and algorithms: • Rate-fixed: core proxies are configured with a fixed number of senders. The overall rate of a core proxy is divided through the sender number. • Rate-aware: core proxies estimate the number of senders. The overall rate of a core proxy is divided through the sender estimate. • Loss-based: same loss rate is sent to all edge proxies. • All simulations use SRED algorithm.

11. Fairness (Columbia University)Rate-based Overload Control • Provider-centric fairness: each source gets the same share • User-centric fairness: each source gets a share proportional to its original incoming load Slide 11

12. Conclusion & Next Steps Simulation Results • The overload control performance seems to differ little between the type of feedback: • Rate-, Loss-, Window- and Signal-based mechanisms all performed well in steady-state as well as transient evaluations. • Of course, the performance does vary depending on the overload control algorithms used and parameter settings of these algorithms. • But: algorithms and parameter settings are likely to be out of scope for an overload control protocol specification. Next Steps • Evaluate additional transient scenarios. • Finalize draft-ietf-sipping-overload-design-01 • Work on a solution!!

13. A Session Initiation Protocol (SIP) Load Control Event Packagedraft-shen-sipping-load-control-event-package-01Charles Shen, Henning Schulzrinne, Arata Koike Session Initiation Protocol (SIP) Overload Controldraft-hilt-sipping-overload-06Volker Hilt, Indra Widjaja, Henning Schulzrinne

14. Filter-based SIP Server Overload Controldraft-shen-sipping-load-control-event-package-01 Filter Spec ID: To: +1-212-555-1234 Time: 9am-10am 2009-1-1 Act: accept rate=NSPA Filter Spec ID: To: +1-212-555-1234 Time: 9am-10am 2009-1-1 Act: accept rate=NEPA Filter Spec ID: To: +1-212-555-1234 Time: 9am-10am 2009-1-1 Act: accept rate= Nmax Enterprise Network A Hotline Callee 212-555-1234 9am-10am, 2009-1-1 Service Provider A Filter Spec ID: To: +1-212-555-1234 Time: 9am-10am 2009-1-1 Act: accept rate=NSPB Enterprise Network B Service Provider B Charles Shen, Henning Schulzrinne, Arata Koike, A Session Initiation Protocol (SIP) Load Control Event Package, draft-shen-sipping-load-control-event-package-01.txt, IETF SIPPING Working Group, Work in Progress. Nov 3, 2008 14

15. Session Initiation Protocol (SIP) Overload Controldraft-hilt-sipping-overload-06 • Overload control mechanism • Enables proxies to send overload control feedback to upstream neighbors. • Feedback is conveyed in SIP responses • New Via Header Parameters • Supports different types of feedback. Currently defined: loss-based. • Specifies the protocol semantics. Open to different overload control algorithms. Reduces load Overload Server S1 Server S2 Via: SIP/2.0/TCP ss1.example.com:5060 ;oc=20;oc_validity=500