Re: [ippm] Proposed changes to default settings in the Capacity metric load adjustment algorithm

["MORTON JR., AL" <[e-mail]>]

Martin/Greg/Tommy,

Thanks, I’ll move the editing ahead with our designated RFC Editor ASAP, probably next week sometime.  There are some additional questions (from Lynne B) that I need to dig-up and answer...

Al

From: Martin Duke <[e-mail]>
Sent: Friday, August 27, 2021 4:08 PM
To: Greg Mirsky <[e-mail]>
Cc: MORTON JR., AL <[e-mail]>; [e-mail]; IPPM Chairs <[e-mail]>; IETF IPPM WG <[e-mail]>
Subject: Re: [ippm] Proposed changes to default settings in the Capacity metric load adjustment algorithm

yes, let's make the change and proceed.

Thanks

On Wed, Aug 25, 2021 at 3:22 PM <[e-mail]<mailto:[e-mail]>> wrote:

Hi, Martin et al.,

my apologies for the late response.

I've reviewed the proposed changes in the default values. I agree that these changes make the out-of-box capacity measurement less sensitive to an occasional non-congestion-related loss of packets while preserving the algorithm's fast ramp-up behavior. Clearly, a win-win update. I support it.



Regards,

Greg Mirsky



Sr. Standardization Expert
预研标准部/有线研究院/有线产品经营部 Standard Preresearch Dept./Wireline Product R&D Institute/Wireline Product Operation Division


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Date: 2021/08/12 10:49
Subject: Re: [ippm] Proposed changes to default settings in the Capacity metric load adjustment algorithm
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Hello IPPM,

If you have any comments about this change, please send them to this list no later than 24 August.

On Tue, Aug 3, 2021 at 3:01 PM MORTON JR., AL <[e-mail]<mailto:[e-mail]>> wrote:
IPPM,

I want to point out that some recent results conducted by others encouraged us to test some additional values for seq error threshold and a wider value range of values for consecutive errored status (during feedback intervals).  We discovered that we would like to revise the default values to make the load adjustment a little less-sensitive to non-congestion-related loss and protect the fast ramp-up from ending prematurely. For example, a very short burst of lost packets spanning the boundary between two feedback intervals is currently sufficient to end fast ramp-up.

The current table in 8.1 contains:
+--------------+-------------+--------------+-----------------------+
| Parameter    | Default     | Tested Range | Expected Safe Range   |
|              |             | or values    | (not entirely tested, |
|              |             |              | other values NOT      |
|              |             |              | RECOMMENDED)          |
+--------------+-------------+--------------+-----------------------+
...
+--------------+-------------+--------------+-----------------------+
| sequence     | 0           | 0, 100       | same as tested        |
| error        |             |              |                       |
| threshold    |             |              |                       |
+--------------+-------------+--------------+-----------------------+
| consecutive  | 2           | 2            | Use values >1 to      |
| errored      |             |              | avoid misinterpreting |
| status       |             |              | transient loss        |
+--------------+-------------+--------------+-----------------------+


The revised table rows would look like this:

+--------------+-------------+--------------+-----------------------+
| Parameter    | Default     | Tested Range | Expected Safe Range   |
|              |             | or values    | (not entirely tested, |
|              |             |              | other values NOT      |
|              |             |              | RECOMMENDED)          |
+--------------+-------------+--------------+-----------------------+
...
+--------------+-------------+--------------+-----------------------+
| sequence     | 10          | 0,1,5,10,100 | same as tested        |
| error        |             |              |                       |
| threshold    |             |              |                       |
+--------------+-------------+--------------+-----------------------+
| consecutive  | 3           | 2,3,4,5      | Use values >1 to      |
| errored      |             |              | avoid misinterpreting |
| status       |             |              | transient loss        |
+--------------+-------------+--------------+-----------------------+

Somehow, persistent non-congestion-related loss had mostly eluded our previous tests. But our goal has been to provide default values that will work in automated testing run by anyone in any implementation or circumstances - not just ~expert users and those who run the udpst utility.

So we'd like to change default values for:

  seq error threshold         from 0 to 10
  consecutive errored status  from 2 to  3

and update our tested range/values column as well.

Al