1 / 15

Chapter 6 outline

6.1 Multimedia Networking Applications 6.2 Streaming stored audio and video RTSP 6.3 Real-time, Interactive Multimedia: Internet Phone Case Study 6.4 Protocols for Real-Time Interactive Applications RTP,RTCP SIP. 6.5 Beyond Best Effort 6.6 Scheduling and Policing Mechanisms (cont)

decker
Download Presentation

Chapter 6 outline

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 6.1 Multimedia Networking Applications 6.2 Streaming stored audio and video RTSP 6.3 Real-time, Interactive Multimedia: Internet Phone Case Study 6.4 Protocols for Real-Time Interactive Applications RTP,RTCP SIP 6.5 Beyond Best Effort 6.6 Scheduling and Policing Mechanisms (cont) 6.7 Integrated Services 6.8 RSVP 6.9 Differentiated Services Chapter 6 outline

  2. Scheduling • scheduling: choose next packet to send on link • FIFO (first in first out) scheduling: send in order of arrival to queue • real-world example? • discard policy: if packet arrives to full queue: who to discard? • Tail drop: drop arriving packet • priority: drop/remove on priority basis • random: drop/remove randomly

  3. Scheduling (more) Priority scheduling: transmit highest priority queued packet • multiple classes, with different priorities • class may depend on marking or other header info, e.g. IP source/dest, port numbers, etc.. • Real world example?

  4. Scheduling (more) round robin scheduling: • multiple classes • cyclically scan class queues, serving one from each class (if available) • real world example?

  5. Scheduling (more) Weighted Fair Queuing: • generalized Round Robin • each class gets weighted amount of service in each cycle • real-world example?

  6. Scheduling and delay (a measure of quality) • Basic scheduling policy • Single queue, no priority, FIFO • Recall, average queuing delay d = 1 / ( )  

  7. Scheduling and delay (more) • Priority scheduling • Simple example: 2 classes/queues, each /2 arrival rates • What are the average delays of two classes? • Higher-priority packets: do you see it? • Lower-priority packets: tricky (notice work-conserving). /2  /2

  8. Scheduling and delay (more) • Round robin scheduling • Simple example: two queues, 1 packet per round, no priority • What is the average queuing delay of a packet? • How about Weighted Fair Queuing? Much more complicated and need queuing theory (beyond this course). /2  /2

  9. Policing mechanisms Goal: limit traffic to not exceed declared parameters Three common-used criteria: • (Long term) Average Rate:how many packets can be sent per unit time (in the long run) • crucial question: what is the interval length: 100 packets per second or 6000 packets per min have same average! • Peak Rate: e.g., 6000 packets per min. (ppm) avg.; 1000 packets per sec. peak rate • (Max.) Burst Size: max. number of packets sent consecutively (with no intervening idle)

  10. Policing mechanisms (more) Token Bucket: limits input to specified Burst Size and Average Rate. • bucket can hold b tokens • tokens generated at rate r token/sec unless bucket full • Over any interval of length t: number of packets admitted less than or equal to (r t + b).

  11. Policing mechanisms (more) Token Bucket: can also limit input to specified Peak Rate p pps. How? Just add a second token bucket, taking the output of the first token bucket as the input. • 2nd bucket can hold 1 token • tokens generated at rate p token/sec unless bucket full

  12. Policing mechanisms (more) • token bucket and WFQ combined provide guaranteed upper bound on delay, i.e., QoS guarantee ! arriving traffic WFQ

  13. Summary: Meeting the principles • Packet classification • Marking at edge; not done by scheduling/policing. • Flow isolation • Multiple queues, different priorities, weights • Policing with leaky bucket to limit (average rate, burst length, peak rate) • High resource utilization • Work-conserving scheduling • Call admission • Guaranteed level of quality (WFQ + leaky bucket) • Resource reservation

  14. 6.1 Multimedia Networking Applications 6.2 Streaming stored audio and video RTSP 6.3 Real-time, Interactive Multimedia: Internet Phone Case Study 6.4 Protocols for Real-Time Interactive Applications RTP,RTCP SIP 6.5 Beyond Best Effort 6.6 Scheduling and Policing Mechanisms 6.7 Integrated Services 6.8 RSVP 6.9 Differentiated Services Chapter 6 outline

  15. Remaining schedule • 04/21, Wednesday IntServ, RSVP • 04/23, Friday 2nd half recap, selected homework solutions, final exam info • 04/26, Monday Lab, bring your question on project#3 • 04/30, Friday Exam, homework#7 due (posted), project#3 due

More Related