Hi Les,
Thank you very much for your response.
On top of your response, I have a few more queries. Please find them below.
1. For Min/Max Unidirectional Link Delay Sub-TLV, there is only one *A-bit.*
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| RESERVED | Min Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | Max Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Does this mean A-bit is applicable only for Min-delay?
IF not, then should we maintain 2 different maximum threshold and
reuse thresholds?
And if both min-delay and max-delay values fall below reuse threshold
we have clear A-bit.
Will below example follow the RFC?
min-delay reuse threshold : 50 usec
min-delay maximum threshold : 100 usec
max-delay reuse threshold : 200 usec
max-delay maximum threshold : 300 usec
*1st measured value:*
min-delay: 110 usec
max-delay: 190 usec
conclusion: Set A bit. (As min-delay value has exceeded max-threshold value?)
*2nd measured value :*
min-delay: 40 usec
max-delay: 320 usec
conclusion : Do nothing (Maintain pervious state of A bit as max-delay
value has exceeded max-threshold value?)
*3rd measured value :*
min-delay: 40 usec
max-delay: 150 usec
conclusion : Clear A bit (As both min-delay and max-delay values are
falling below resue threshold?)
Thanks & Regards,
Gurusiddesh V N
On Fri, Apr 23, 2021 at 4:51 PM Les Ginsberg (ginsberg) <[email protected]>
wrote:
> Gurusiddesh –
>
>
>
> The short answer to all your questions is “yes”.
>
> More inline.
>
>
>
> *From:* Gurusiddesh Nidasesi <[email protected]>
> *Sent:* Thursday, April 22, 2021 10:33 PM
> *To:* Acee Lindem (acee) <[email protected]>
> *Cc:* [email protected]; [email protected]; [email protected]; Les
> Ginsberg (ginsberg) <[email protected]>; Dona Maria John <
> [email protected]>; Vikram Agrawal <[email protected]>;
> Mahalakshmi Kumar <[email protected]>
> *Subject:* Re: [Lsr] Doubt regarding A bit set/clear
>
>
>
> Hi All.
>
>
>
> *Gentle Reminder!*
>
>
>
> Regards,
>
> Gurusiddesh V N
>
>
>
> On Mon, Apr 19, 2021 at 6:54 PM Acee Lindem (acee) <[email protected]> wrote:
>
> Gurusiddesh,
>
>
>
> I’ll defer to the RFC authors on your question. However, please refrain
> from referring to bits as being “unset”. They are set or clear.
>
>
>
> Thanks,
>
> Acee
>
>
>
> *From: *Lsr <[email protected]> on behalf of Gurusiddesh Nidasesi <
> [email protected]>
> *Date: *Monday, April 19, 2021 at 6:13 AM
> *To: *"[email protected]" <[email protected]>
> *Cc: *Spencer Giacalone <[email protected]>, Stefano Previdi <
> [email protected]>, "Les Ginsberg (ginsberg)" <[email protected]>,
> Dona Maria John <[email protected]>, Vikram Agrawal <
> [email protected]>, Mahalakshmi Kumar <
> [email protected]>
> *Subject: *[Lsr] Doubt regarding A bit set/unset
>
>
>
> Hi All,
>
>
>
> I had a query regarding setting/unsetting A bit.
>
>
>
> https://tools.ietf.org/html/rfc8570#section-4.1 states that
>
> A bit: This field represents the Anomalous (A) bit. The A bit is
>
> set when the measured value of this parameter exceeds its
>
> configured maximum threshold. The A bit is cleared when the
>
> measured value falls below its configured reuse threshold. If the
>
> A bit is cleared, the sub-TLV represents steady-state link
>
> performance.
>
>
>
> So does it mean we have to have two configurations one for reuse and another
> for maximum threshold?
>
> *[Les:] Yes. The goal is to prevent altering the advertisement due to small
> oscillations of the advertisement. If you had a single value then if the
> measured value bounced between (for example) +1/-1 of the threshold) the
> advertisement of the A-bit would change rapidly – this is undesirable.*
>
> *So the max threshold triggers setting of the A-bit and the reuse threshold
> triggers clearing of the bit. The reuse threshold provides some confidence
> that the measurement has stabilized below the maximum anomalous threshold.*
>
>
>
>
>
> Will below example follow the RFC?
>
> reuse threshold : 50 usec
>
> maximum threshold : 100 usec
>
> 1st measured value : 110 usec
>
> conclusion: Set A bit.
>
>
>
> 2nd measured value : 75 usec
>
> conclusion : Do nothing (Maintain pervious state of A bit as the value is
> less than reuse or greater than threshold)
>
>
>
> 3rd measurement value : 30 usec
>
> conclusion: Unset A bit.
>
>
>
> *[Les:] Yes this conforms to specified behavior.*
>
>
>
> If we have to have two configuration for threshold to set/unset A bit, will
> they be different from the threshold that we use for advertisements?
>
> *[Les:] **Yes . ** This is clearly stated in Section 5:*
>
>
>
> *“4. For sub-TLVs that include an A bit, an additional threshold*
>
> * SHOULD be included corresponding to the threshold for which the*
>
> * performance is considered anomalous (and sub-TLVs with the A bit*
>
> * are sent)…”*
>
> * Les*
>
>
>
>
>
>
>
> Regards,
>
> Gurusiddesh V N
>
>
> .
>
>
>
>
> --
>
> Thanks,
>
> Gurusiddesh V N
>
>
> .
>
--
Thanks,
Gurusiddesh V N
--
.
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