Re: [Lsr] RFC 8919, RFC 8920, Flex Algo, and Flex Algo BW Constraints

["Acee Lindem (acee)" <[e-mail]>]

Speaking as a WG member:

Hi Ron,
My rationale is #1. The LSR WG developed ASLAs to cover usage of the link attributes (including metrics) for different applications and mitigate all the vagaries of the original TE link attribute specifications. ASLAs are implemented and deployed. I believe it would be a mistake to bifurcate the IGP standards with yet another way of encoding link attributes for different applications.
Thanks,
Acee

From: Lsr <[e-mail]> on behalf of Ron Bonica <rbonica=[e-mail]>
Date: Thursday, August 12, 2021 at 3:46 PM
To: "Acee Lindem (acee)" <acee=[e-mail]>, "[e-mail]" <[e-mail]>
Subject: Re: [Lsr] RFC 8919, RFC 8920, Flex Algo, and Flex Algo BW Constraints

Acee,

Please help me to parse your message. It is clear that you want draft-ietf-lsr-flex-algo-bw-con to specify ASLA’s. However, your rationale is not so clear.

It is not because RFC 8919 mandates ASLA. In fact, we agree that it would be strange for an RFC to include a mandate that precludes future proposals.

Are any of the following your rationale:


1)     Because there is a good technical reason for draft-ietf-lsr-flex-algo-bw-con to specify ASLA

2)     Because it is possible, but not necessary, for draft-ietf-lsr-flex-algo-bw-con to specify ASLA

3)     Because it was the unstated intention of RFC 8919 to include a mandate that precludes future proposals (although we agree that this would be strange).

For the purposes of full disclosure, I think discussion regarding the first rationale would be fruitful. However, I don’t think very much of the second or third rationale.

                                                                                                                                                    Ron





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From: Lsr <[e-mail]> On Behalf Of Acee Lindem (acee)
Sent: Tuesday, August 10, 2021 4:43 PM
To: [e-mail]
Subject: [Lsr] RFC 8919, RFC 8920, Flex Algo, and Flex Algo BW Constraints

[External Email. Be cautious of content]

Speaking as a WG Member:

  In reviewing RFC 8919 and RFC 8920, it is clear that the ASLA mechanism was to be used for new link attributes and applications. While the documents do not mandate that there never could be a new way to advertise link attributes, this was clearly the intent. Indeed, it would be strange for an RFC to include a mandate that precluded future proposals. The advertisement enablement and deployment sections of these documents specifically cover future attributes and applications.

  Given that we have ASLAs as building blocks, I don’t really see a reason to introduce the generic metric. The proponents say it isn’t an alternative to ASLAs but their examples cite different applications using different metric types (i.e., application-specific metrics). Also, given that ASLA are used by the base Flex Algo draft, it would be inconsistent to diverge for Flex Algo BW constraints.

  Consequently, I would request that draft-ietf-lsr-flex-algo-bw-con-01 revert to using ASLAs. Based on the LSR Email discussion prior to IETF 111, this was definitely the consensus.

Thanks,
Acee