Re: [sip-overload] draft-ietf-soc-overload-rate-control-04.txt

["Yu, James" <[e-mail]>]

Janet,

For my comment on section 3.4 (the first one below), the current text does not provide any value.  The client's arrival rate could be well below the target SIP request rate when its load is light so the fact that the client may not achieve the target SIP request rate (the max. rate it is allowed to send to the server) is well understood.  But with your explanation on the "delta" part, the text then makes sense.  Please add some discussions on the "delta" aspect so that even if the average arrival rate at the client is higher than the target SIP request rate the client at times may not send more than what the target SIP request rate allows due to the fluctuation of the arriving requests at the client.

For the comment on section 3.5.1, I agree with your proposed change.

For the rate control, the server could calculate the arrival rate from each communicating client so that it could allocate the overall target SIP request rate to the clients based on their arrival rates known to the server.  But another option is for the client to "optionally" include its calculated arrival rate in its request to the server when rate control related parameters are present.  Should this option be evaluated/included to relieve the server from doing the arrival rate calculations.  This would be beneficial to a server when it receives the requests from many clients.

James

From: Janet P Gunn [mailto:[e-mail]]
Sent: Friday, June 28, 2013 3:34 PM
To: Yu, James
Cc: [e-mail]; [e-mail]; [e-mail]
Subject: Re: [sip-overload] draft-ietf-soc-overload-rate-control-04.txt

James,

It is a little hard to respond in email when your comments are in a separate document, but here goes.


section 3.4
ID says:
"Note that the target SIP request rate is a max rate that may not be
   attained by the arrival rate at the client, and the server cannot
   assume that it will."

Your comment :
"Not clear what value this paragraph tries to add.  Is it saying that the client's arrival rate may be lower than the target SIP request rate?  "

Yes.

Suppose the server want to limit the total rate of arriving SIP messages to 100 / sec, and has 10 clients.  Each client has a high variance in its message rate, but together they are well above 100 messages per sec

If it sets the rate at 10 messages per second for each of the clients, it will almost certainly end up  with an overall average of less than 100 messages per sec, because some clients will be in a "lull" while others are busy.  This is good from a throttling perspective, but, assuming messages are correlated with revenue, bad/wasteful from a revenue, or overall productivity perspective.  So the server might want to set the rate per client to 10 + delta, where delta is going to be very specific to operating environment.

---
In section  3.5.1, bottom of page 8
ID says:
"And the larger
   the difference between TAU1 and TAU2, the closer to the control is
   to strict priority."

You propose changing it to:
"And the larger
   the difference between TAU1 and TAU2, the closer  the control is
   to strict priority queuing."

I agree with taking out the redundant "to".  But I disagree wit adding "queuing".  There is no queuing, priority or otherwise involved.

You could say:
"And the larger
   the difference between TAU1 and TAU2, the closer  the control is
   to strict priority treatment."

where " strict priority treatment" would refer to the case where non-priority messages are restricted to a total (priority + non-priority) rate of 10 messages per second, but priority messages can continue to be sent as long as the total (priority + non-priority) rate is less than 12 messages per second.

At least, I think that is what Eric and  Philip are trying to say.

Janet





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From:        "Yu, James" <[e-mail]<mailto:[e-mail]>>
To:        "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>
Date:        06/28/2013 08:10 AM
Subject:        [sip-overload] draft-ietf-soc-overload-rate-control-04.txt
Sent by:        [e-mail]<mailto:[e-mail]>
________________________________



Salvatore,

Please see the attachment for my comments.

I pasted the text to a word document to trace/show the proposed changes and comments.

Regards,

James
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