Re: [Ieprep] proposed charter 5 priority levels
Curtis Villamizar <curtis@occnc.com> Wed, 27 September 2006 16:44 UTC
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To: "Roy, Radhika R." <RADHIKA.R.ROY@saic.com>
Subject: Re: [Ieprep] proposed charter 5 priority levels
In-reply-to: Your message of "Wed, 27 Sep 2006 09:16:59 EDT." <62D92A9A02BCC845B202323D49A48426E1CE7E@0591-ITS-EXMP02.us.saic.com>
Date: Wed, 27 Sep 2006 13:32:31 -0400
From: Curtis Villamizar <curtis@occnc.com>
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Cc: "Ash, Gerald R (Jerry), ALABS" <gash@att.com>, ieprep@ietf.org
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In message <62D92A9A02BCC845B202323D49A48426E1CE7E@0591-ITS-EXMP02.us.saic.com> "Roy, Radhika R." writes: > > > Can SIP priority level be mapped to media which is the main objective of > QOS? If not, what help does it provide with respect to QOS? > > RRR Both SIP priority and DSCP are carried in the RSVP signaling (or NSIS as Jerry pointed out). This allows queues to be dynamically adjusted if need be. Only one DSCP marking is being proposed on the traffic itself so that the SIP priority in the traffic itself cannot be distinguished. This is not regarded as a problem since the traffic is policed and the reservation for this DSCP marking should assure zero drop as long as the policing is effective. This "one marking for all" scheme does preclude the use of highly efficient multiplexing that might introduce limited loss to the lowest priority traffic or allow all traffic classes to exceed their stated allocation (ie: AF where marking is done at ingress, not policing). This does not preclude multiplexing gains. For example, many audio encodings peak at 5-10 times their average BW. This can be specified in the peak, burst size, and average values in RSVP with the policers and queuing set (dynamically if needed) to allow multiplexing but keep loss at zero. Worst case would still be a spike in delay. For example consider audio near a disaster scene. An explosion could cause a spike in audion on many senders. There would be no loss per se but an increase in delay that would exceed the playback jitter buffering and cause a click and may move the jitter buffer out to a longer playback point. If the playback buffer could not compensate, the audio playback of the explosion would not be accurate, but that is probably the least of anyone's worries in this scenario. After the explosion audio would return to normal. Note that policers and queuing can be set dynamically or staticly. If set staticly then blocking would occur when limits were hit. If the ETS traffic is very small compared to the capacity of the network it is running over then static may make sense, or just static queue allocation in the network core. I hope this thoroughly answered your question (and correctly too, if not experts on this please jump in and correct me). I'm learning too but I think I'm coming up to speed. Curtis _______________________________________________ Ieprep mailing list Ieprep@ietf.org https://www1.ietf.org/mailman/listinfo/ieprep
- Re: [Ieprep] proposed charter 5 priority levels John Rosenberg
- Re: [Ieprep] proposed charter 5 priority levels Curtis Villamizar
- RE: [Ieprep] proposed charter 5 priority levels Ash, Gerald R (Jerry), ALABS
- Re: [Ieprep] proposed charter 5 priority levels Curtis Villamizar
- Re: [Ieprep] proposed charter 5 priority levels John Rosenberg
- Re: [Ieprep] proposed charter 5 priority levels Fred Baker
- Re: [Ieprep] proposed charter 5 priority levels Curtis Villamizar
- Re: [Ieprep] proposed charter 5 priority levels John Rosenberg
- Re: [Ieprep] proposed charter 5 priority levels James M. Polk
- Re: [Ieprep] proposed charter 5 priority levels James M. Polk