Re: I-D Action: draft-ietf-bfd-yang-06.txt

[Mahesh Jethanandani <[e-mail]>]

> On Jul 31, 2017, at 1:55 PM, Jeffrey Haas <[e-mail]> wrote:
> 
> Mahesh,
> 
>> On Jul 31, 2017, at 4:26 PM, Mahesh Jethanandani <[e-mail]> wrote:
>> 
>> Jeff,
>> 
>>> On Jul 31, 2017, at 10:05 AM, Jeffrey Haas <[e-mail]> wrote:
>>> 
>>> On Fri, Jul 28, 2017 at 03:58:06PM -0700, Mahesh Jethanandani wrote:
>>>> The changes are done and pushed to GitHub. Use the grouping client-cfg-parms.
>>> 
>>> Question: For implementations that use Echo mode, is that something the
>>> protocol client configuration impacts or is it chosen by the system
>>> automatically?
>> 
>> I am not sure I understand. 
>> 
>> For Echo mode, there is a separate grouping called echo-cfg-parms that allows clients to specify the desired-min-echo-tx-interval and required-min-echo-rx-interval. 
>> 
>> That is somehow different from desired-min-tx-interval and required-min-rx-interval that one can specify for a normal BFD session. For the life of me, I do not understand why the two need to be different :-(. I must be getting amnesia. Maybe one of the co-authors will jog my memory.
> 
> The protocol permits those values to be distinct from the async ones.  They should be in a separate set of params.

Agree. 

> 
> My point, unless my very quick glance at the module mislead me, is that you can't configure to use echo mode - if it's supported - in the grouping imported by the IGPs.

In the current model, it is modeled as a separate grouping with its own set of parameters. The expectation is that implementations that want to define echo mode would use the grouping. Defining the parameters also implicitly defines that echo-mode is enabled. Are you saying that using the echo grouping is not enough? 

But I do think that the parameters needs to be further protected by an if-feature statement that says

  grouping echo-cfg-parms {
    if-feature echo-mode;
    description 
      "BFD grouping for echo config parameters”;

> 
> My implementation doesn't support echo, so I don't have any opinion about where configuration of those belongs or not.

With the feature statement, these echo parameters can exist inside of client-cfg-parms, instead as a separate grouping and will be included by the platform only if the feature is defined. And this would be my preference. Is that what folks would also prefer?

> 
> -- Jeff
> 
> 
> 
>> 
>> Cheers.
>> 
>>> 
>>> -- jeff
>> 
>> Mahesh Jethanandani
>> [e-mail] <mailto:[e-mail]>
Mahesh Jethanandani
[e-mail]