1 / 13

AVPF vs AVP RTCP Intevals

AVPF vs AVP RTCP Intevals. AVP and AVPF Interop. Whe AVP and AVPF is interoperating one must choose certain parameters correctly. In trying to determine the most suitable based on the timing rules a AVPF timing issue was found that is problematic for interop .

mahala
Download Presentation

AVPF vs AVP RTCP Intevals

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. AVPF vs AVP RTCP Intevals

  2. AVP and AVPF Interop • Whe AVP and AVPF is interoperating one must choose certain parameters correctly. • In trying to determine the most suitable based on the timing rules a AVPF timing issue was found that is problematic for interop. • Based on simulations of the algorithm • There might be bugs in the simulation

  3. avg_rtcp_size:200 bytes • RR: 500 bps • RS: 1000 bps • Senders: 1 • Members: 2 • We_sent: FALSE • Trr-int:5 • Tmin:5 (AVP only) AVPF vs AVP Problems • Simulated distributions of RTCP transmission interval • Tn is AVPF sending rules without suppression or reconsideration, i.e. Td*rand(0.5,1.5) • AVPF(TN no supp) is with reconsideration • AVP is RFC 3550 including reconsideration • When Td calculation becomes close to, but below Trr-int AVPF suppression pushes transmissions interval distribution upwards and uneven in distribution

  4. avg_rtcp_size:200 bytes • RR: 10000 bps • RS: 1000 bps • Senders: 1 • Members: 2 • We_sent: FALSE • Trr-int:5 • Tmin:5 (AVP only) Td << Trr-int • Here the RTCP bandwidth portion the calculation uses has been increased from 500 to 10k bps, i.e. 20 times • Reduces Td • Therefore both Tn and AVPF without suppression are all ending up in the 0.25-0.5 s range • As can be seen the AVPF distribution are mostly uniform in the range 0.5-1.5*Trr-int, with a little bit of tail • However, still longer tail than AVP

  5. avg_rtcp_size:200 bytes • RR: 500 bps • RS: 1000 bps • Senders: 1 • Members: 4 • We_sent: FALSE • Trr-int:5 • Tmin:5 (AVP only) Td>Trr-Int • Same RR as the problem slide 500 bps, but now with 4 members, i.e. 3 receivers sharing RR • As can be seen here only a little bit of suppression happens at the 4-7.5 s range, i.e. 0.5-1.5*Trr-int. • That suppression do show up as bit of long tail above 12.5 seconds

  6. Question: What gives best interop? • So how does an AVPF user set his parameters to best interoperate from a perspective of avoiding accidental timeout: • The Regular RTCP transmission distribution is one factor which is depending on: • Trr-int that sets suppression • The Td deciding values: • Members • Senders • RR and RS • Average RTCP packet size • The other is when AVPF times out AVP participants • 5*Trr-Int given that Trr-int != 0 • Thus we must combine Trr-int large enough so that an AVPF particpant do not time out AVP participants • At the same time AVPF regular RTCP transmission interval should not be so long that AVP times out • How many consecutive packet losses are needed before timeout happens?

  7. Td parameterization • When using AVPF one should try to avoid setting RR and RS so that Td in the given session are close to Trr-int. • The tail in the AVPF RTCP interval distribution is at its extreme at 1.5*Trr-int + 1.5*Td/1.21828 • Worst case Td = Trr-int: 2.73*Trr-int • Tdshould preferably be less than 1/4th of Trr-Int • That gives us max tail length of: • 1.5*Trr-int + 1.5*Trr-int/(4*1.21828) ≈ 1.81 Trr-int • AVP’s tail ends at 1.5*Tmin/1.21828 = 1.231*Tmin • Given that Td is less than Tmin • Otherwise replace Tmin with Td

  8. Equalizing the tails • If we would like to have equally values for the extreme randomization intervals given that Td is less than Tmin and Trr-int: • Trr-int = 1.231/1.81*Tmin • 1.81 (following the Td < 1/4thTrr-int recommendation) • Tmin = 5 s => Trr-int = 3.40 s • This ensures that no AVPF session participant is more likely to time out than an AVP one. • However, the reverse is not true.

  9. Timing out AVP participants • An AVPF participant will timeout an participant at 5*Trr-int, • Equivalent of AVP participants using a Trr-int as a factor for number of intervals before timing out. • This assumes Tmin=5s and Td<Tmin

  10. Finding the optimal both ways • So what is the point of least decrease in timeout robustness performance: • Given that Tmin = 5 s and Td < Tmin • AVPF intervals before AVP timeout(target): • 5*Tmin/(Trr-int) • AVPF intervals before AVP timeout(1/4 * Trr-int): • 5*Tmin/(Trr-int*1.81) • AVPF Intervals before AVP timeout (1/10 * Trr-int): • 5*Tmin/(Trr-int*1.623) • AVP intervals before AVPF timeout (target): • 5*Trr-int/5 • AVP intervals before AVPF timeout (worst case): • 5*Trr-int/(1.231*Tmin)

  11. Number of Reporting Intervalsgiven Trr-int

  12. Recommendations • Based on these findings it appears that the following recommendations for AVPF vs AVP interop should be given: • RR and RS sufficiently large that Td becomes less than ¼ of Trr-int • Trr-int should be chosen as 4.0

  13. Future Work? • Do the Suppression algorithms bad behavior needs to be addressed?

More Related