Re: Correcting BFD Echo model

[Greg Mirsky <[e-mail]>]

Hi Reshad,
thank you for providing the context to BFD Echo TX. Indeed, I'm familiar
with implementations that use BFD Echo as Echo request/reply and thus Tx
would be in RPC, not in configuration. I think that it would be good to
discuss this in Chicago unless we hear comments from others on the list.

Regards,
Greg

On Mon, Feb 27, 2017 at 5:56 AM, Reshad Rahman (rrahman) <[e-mail]>
wrote:

> Hi Greg,
>
> draft-zheng-mpls-ls-ping-yang-cfg defines transmit interval in RPC
> because all ping operations are done via RPC.  I do not consider BFD echo
> to be “on demand” like LSP Ping (caveat: this is possibly due to the BFD
> configuration/implementation I am most familiar with).
>
> Regards,
> Reshad.
>
> From: Greg Mirsky <[e-mail]>
> Date: Monday, February 27, 2017 at 1:07 AM
> To: Mahesh Jethanandani <[e-mail]>
> Cc: Reshad <[e-mail]>, "[e-mail]" <[e-mail]>, "
> [e-mail]" <[e-mail]>
> Subject: Re: Correcting BFD Echo model
>
> Hi Mahesh,
> BFD Echo transmit interval is not part of RFC 5880, only Rx interval is.
> And Rx interval is sufficent to reflect whether local system is willing to
> receive BFD Echo messages from the particular BFD peer. Introduced
> desired-min-echo-tx-interval functionally overlaps with the
> standard-defined required-min-echo-rx-interval. Hence my suggestion to
> remove desired-min-echo-tx-interval from grouping
> bfd-grouping-echo-cfg-parms. But operators need a way to specify transmit
> interval for on-demand OAM command like BFD Echo, IP ping or LSP ping. I
> couldn't find YANG model proposal for IP ping but in
> draft-zheng-mpls-lsp-ping-yang-cfg transmit interval used in RPC, not as
> part of configuration.
>
> Regards,
> Greg
>
>
> On Sun, Feb 26, 2017 at 8:33 PM, Mahesh Jethanandani <
> [e-mail]> wrote:
>
>>
>> On Feb 26, 2017, at 4:39 PM, Greg Mirsky <[e-mail]> wrote:
>>
>> Hi Reshad,
>> thank you for the question. Here's my reasoning:
>>
>>    - only Required Min Echo RX Interval is present in RFC 5880 and it
>>    allows to indicate not only the smallest interval between consecutive BFD
>>    Echo packets but whether system supports BFD Echo function at all;
>>    - since BFD Echo may be transmitted only when the session state is
>>    Up, operator is fully equipped to learn the value of Required Min Echo RX
>>    Interval of its BFD peer and to set Echo transmit interval accordingly;
>>    - requesting BFD Echo, in my opinion, is no different from requesting
>>    IP ping or LSP ping.
>>
>> Hence my conclusion - transmit interval for BFD Echo is more suitable in
>> RPC then as configuration parameter.
>>
>>
>> I do not think that is reason enough for it to be a RPC.
>>
>> A RPC is an operation one defines in the YANG model specifying both input
>> and output parameters. There are no operations to be had here.
>>
>> And the definition and desired behavior of desired-min-echo-tx-interval
>> is not very different from required-min-echo-x-interval. It is as the
>> definition says, a configuration parameter that can be set, with zero
>> having a special meaning in both cases.
>>
>>
>> Regards,
>> Greg
>>
>> On Sun, Feb 26, 2017 at 2:52 PM, Reshad Rahman (rrahman) <
>> [e-mail]> wrote:
>>
>>> Hi Greg,
>>>
>>> Can you please explain why you believe this should go in RPC?
>>>
>>> Regards,
>>> Reshad.
>>>
>>> From: Greg Mirsky <[e-mail]>
>>> Date: Saturday, February 25, 2017 at 6:48 PM
>>> To: "[e-mail]" <[e-mail]>, "[e-mail]"
>>> <[e-mail]>
>>> Subject: Correcting BFD Echo model
>>> Resent-From: <[e-mail]>
>>> Resent-To: <[e-mail]>, Reshad <[e-mail]>, <
>>> [e-mail]>, <[e-mail]>, <
>>> [e-mail]>
>>> Resent-Date: Saturday, February 25, 2017 at 6:48 PM
>>>
>>> Dear All,
>>> I've reviewed the BFD YANG model and now I'm thinking that desired-min-echo-tx-interval
>>> and attributing to it the behavior, i.e. when the value is 0, of Required
>>> Min Echo RX Interval are not in the right place. I think that definition of
>>> desired transmit interval of BFD Echo should be in corresponding RPC
>>> definition, not in configuration part of the model.
>>> Appreciate your comments.
>>>
>>> Regards,
>>> Greg
>>>
>>
>>
>>
>