Re: [Lsr] IGP TE Metric Extensions

"Ketan Talaulikar (ketant)" <> Tue, 05 June 2018 11:30 UTC

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From: "Ketan Talaulikar (ketant)" <>
To: Muthu Arul Mozhi Perumal <>, "Stefano Previdi (IETF)" <>
CC: "" <>, Jeff Tantsura <>
Thread-Topic: [Lsr] IGP TE Metric Extensions
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Date: Tue, 05 Jun 2018 11:30:02 +0000
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Subject: Re: [Lsr] IGP TE Metric Extensions
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Hi Muthu,

The Sections 5, 6 and 7 of these drafts are critical as it impacts the IGP protocol operation and stability though it is not an integral part of the IGP protocol machinery. This functionality in a system, whether achieved in the IGP/measurement/some-other module, is an implementation specific aspect.

To answer your question, these aspects may be implemented outside the core IGP module and the IGPs simply flood these while satisfying the aspects specified in the document.


From: Lsr <> On Behalf Of Muthu Arul Mozhi Perumal
Sent: 05 June 2018 16:42
To: Stefano Previdi (IETF) <>
Cc:; Jeff Tantsura <>
Subject: Re: [Lsr] IGP TE Metric Extensions

​Please see inline..​

On Fri, Jun 1, 2018 at 2:34 AM, Stefano Previdi (IETF) <<>> wrote:

On Thu, May 31, 2018, 6:15 PM Muthu Arul Mozhi Perumal <<>> wrote:
Thanks, Jeff. Would be good to have this clarified in
draft-ginsberg-isis-rfc7810bis. My original message seems to have been stripped off, so including it again for the lsr list..

​Both RFC 7810 and RFC 7471 say that:

   The measurement interval, any filter coefficients, and any
   advertisement intervals MUST be configurable per sub-TLV.

   Additionally, the default measurement interval for all sub-TLVs
   SHOULD be 30 seconds.

However, both RFCs initially say that they only describe mechanisms for disseminating performance information and methods of measurements is outside their scope.

Moreover, for a first time reader, it seems to suggest that the measurement interval and filter coefficient must be supported and configurable under the IGP.

No. This is not suggested in any form.
It is clearly indicated that the draft does not deal with measurements which means no recommendation is made.

In a system supporting multiple IGPs, I would expect that they be implemented outside the IGP and the IGPs just disseminate the information provided to them.

Thoughts, especially from an implementation standpoint?

Again, the draft is only about dissemination, not measurements..

​How is the measurement interval and filter coefficients described in the draft related to dissemination?​

​   The measurement interval, any filter coefficients, and any
   advertisement intervals MUST be configurable per sub-TLV.

   Additionally, the default measurement interval for all sub-TLVs
   SHOULD be 30 seconds.​

If your question is related to configuration and implementation of measurements, well it will not be addressed by this draft.

We intentionally left out this part that does not belong to the igp protocol machinery.

​Which of the functionalities described in sections 5, 6, 7 of the draft belong to the IGP protocol machinery?




On Thu, May 31, 2018 at 11:37 AM, Jeff Tantsura <<>> wrote:

LSR would be a more suitable list to post to, CCed.


> On May 30, 2018, at 18:06, Muthu Arul Mozhi Perumal <<>> wrote:
> Muthu

Lsr mailing list<>