Re: [Dime] WGLC #3 for draft-ietf-dime-doic-rate-control-04

["Gunn, Janet P" <[e-mail]>]

I agree with most of Misha's comments.

The one I do not completely agree with is this:

" Can't it we simplify the description and make it shorter at the same time?
Loss algorithm is about the case with a specific traffic rate. Thus, the amount of the abated traffic directly depends on its rate.
In this case the reporting node just says to a reacting one: "I want you to send less traffic".
While rate algorithm is about the traffic rate itself. In this case a reporting node says to a reacting one: "I want you to sent traffic slower""

I agree it would be good to make the description simpler and shorter.

But I do not agree with the suggestion that "Loss = less traffic" and "Rate = slower traffic".

Both Loss and Rate = less traffic.  It is just a difference in how the "less" is determined.

Loss = "reduce traffic BY x%"
Rate = "reduce traffic TO y messages per second"

When you have a number of sources, each of which has a relatively consistent message rate, though some may have higher rates than others, Loss makes sense.
- Because each is relatively consistent, reducing "BY x%" is likely to reduce the offered load to the appropriate level
- Using "BY x%" spreads the cuts "fairly" across the sources.

When you have a number of sources, each of which has a widely fluctuating ("bursty") message rate, Loss makes less sense.
- Because each source is bursty, reducing "BY x%" is likey to cut either too much (if the message rate drops) or not enough (if the message rate spikes)
- Using "TO y messages per second" ensures that the offered load will be reduced to the  appropriate level.
- It may or may not do it "fairly", depending on whether you give all the sources the same  requested rate, or if you adjust the requested rate based on the historical, long term, average rate of that source.

Janet
From: DiME [mailto:[e-mail]] On Behalf Of Misha Zaytsev
Sent: Thursday, January 26, 2017 4:36 PM
To: jouni.nospam <[e-mail]>
Cc: [e-mail]
Subject: Re: [Dime] WGLC #3 for draft-ietf-dime-doic-rate-control-04

Hi,

Here are my comments to the draft:

1. section 1.


If the service requests that result in Diameter transactions increase quickly...

2. section 1. corrected misprints


Consider the case where a reacting (?) node is handling 100 service

   requests per second, where each of these service requests results in

   one Diameter transaction being sent to a reporting node.  If the

   reporting node is approaching an overload state, or is already in an

   overload state, it will send a Diameter overload report requesting a

   percentage reduction in traffic sent.  Assume for this discussion

   that the reporting node requests a 10% reduction.  The reacting node

   will then abate (diverting or throttling) ten Diameter transactions per

   second, sending the remaining 90 transactions per second to the

   reporting node.

3. section 1, reporting nodes -> reporting node's


The reacting node will continue to honor the reporting node's request for a 10% reduction in traffic.

4. section 1, question

Can't it we simplify the description and make it shorter at the same time?
Loss algorithm is about the case with a specific traffic rate. Thus, the amount of the abated traffic directly depends on its rate.
In this case the reporting node just says to a reacting one: "I want you to send less traffic".
While rate algorithm is about the traffic rate itself. In this case a reporting node says to a reacting one: "I want you to sent traffic slower"

This is just an idea/proposal in which way the description can be simplified.
If this is the matter of preference, then OK.

Also, could it be clarified the meaning of the following statement?
What potential to make the situation worse is meant here?


This control feedback loop has the potential to make the situation worse.

5. section 5.1/general

report-type -> report type
DiameterID -> DiameterIdentity

6. section 5.5./general

Rate algorithm -> rate algorithm (if not at the beginning of the statement)

7. section 5.5

Probably "MUST" is to be used?


When sending an overload report for the rate algorithm, the OC-

   Maximum-Rate AVP MUST be included and the OC-Reduction-Percentage AVP MUST not

   be included.

8. section 5.6


Once a determination is made by the reacting node that an individual

   Diameter request is to be subjected to abatement treatment then the

   procedures for throttling and diversion defined in [RFC7683] and

   [I-D.ietf-dime-agent-overload] are applied.

9. section 6.1.1

Probably, it is better to use bit representation of 4, isn't it?


OLR_RATE_ALGORITHM (0x000000000000000100)

10. section 6.2.1 corrected misprints


The OC-Maximum-Rate AVP (AVP code TBD1) is of type Unsigned32 and

   describes the maximum rate that the sender is requested to send

   traffic.

11. section 7.1

To be honest, I do not see the value of the text in this section. It just formulates already defined things in a shorter form.
Is it really worth having it in the spec?

In general, let me state my personal opinion: I think we should take only really meaningful info from SIP RFC, not just pull the content with the appropriate changes to be inline with Diameter RFC7683...

12. section 7.2

It is clear that the reacting nodes may send less than the specified OC-Maximum-Rate value.
They should not send more than the specified OC-Maximum-Rate value, right?

Not sure what is the purpose of the 2nd paragraph...


Note that the AVP for the rate algorithm is an upper bound (in

   request messages per second) on the traffic sent by the reacting node

   to the reporting node.  The reacting node may send traffic at a rate

   significantly lower than the upper bound, for a variety of reasons.



   In other words, when multiple reacting nodes are being controlled by

   an overloaded reporting node, at any given time some reacting nodes

   may receive requests at a rate below its target maximum Diameter

   request rate while others above that target rate.  But the resulting

   request rate presented to the overloaded reporting node will converge

   towards the target Diameter request rate.

The things below are already described in the above sections, aren't they?
If so, what is the reason behind to duplicate the info?


Upon detection of overload, and the determination to invoke overload

   controls, the reporting node MUST follow the specifications in

   [RFC7683] to notify its clients of the allocated target maximum

   Diameter request rate and to notify them that the rate overload

   abatement is in effect.



   The reporting node MUST use the OC-Maximum-Rate AVP defined in this

   specification to communicate a target maximum Diameter request rate

   to each of its clients.

13. Upper case in section titles for section 7.3.1, 7.3.2, 7.3.3, 8.1 and 8.2

14. section 9.  apply-> are applied (if my understanding is correct)


As such, all of the security considerations outlined in [RFC7683] are applied to the rate overload

   abatement mechanism.

If more issues are found, I will add them to the list later on.

Best regards,

/Misha



2017-01-23 4:27 GMT+03:00 jouni.nospam <[e-mail]<mailto:[e-mail]>>:
Folks,

This mail starts the WGLC #3 for draft-ietf-dime-doic-rate-control-04.
The WGLC ends next Sunday 2/5/2017 (PDT).

Please, read & review the draft, provide your support or opposition and/or comments to the list.

Just reminding.. no comments/reviews on the document, I cannot conclude the WGLC has passed.


Regards,
        Jouni
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