Hi Les, Thanks for the quick response and confirmation.
Regards, Gurusiddesh V N On Fri, Apr 23, 2021 at 7:00 PM Les Ginsberg (ginsberg) <[email protected]> wrote: > Gurusiddesh - > > > > *From:* Gurusiddesh Nidasesi <[email protected]> > *Sent:* Friday, April 23, 2021 5:58 AM > *To:* Les Ginsberg (ginsberg) <[email protected]> > *Cc:* Acee Lindem (acee) <[email protected]>; [email protected]; > [email protected]; [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 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? > > *[Les:] The RFC states in Section 4.2 (emphasis added):* > > > > *“A bit: This field represents the Anomalous (A) bit. The A bit is* > > * set when one or more measured values exceed a configured maximum* > > * threshold…”* > > > > *I think the rest you can figure out for yourself.* > > > > * Les* > > > > > > > > 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 > > > . > -- Thanks, Gurusiddesh V N -- .
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