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List:       ms-ospf
Subject:    Re: [Lsr] Last Call: <draft-ietf-lsr-isis-srv6-extensions-14.txt> (IS-IS Extension to Support Segmen
From:       Peter Psenak <ppsenak=40cisco.com () dmarc ! ietf ! org>
Date:       2021-05-14 16:32:32
Message-ID: f894f86c-9921-c544-0828-49f84a704a0d () cisco ! com
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Hi,

I'm fine with the below.

Do folks have any concerns with the below, or can I update the draft?

Please speak up if you disagree.

thanks,
Peter




On 12/05/2021 17:33, Les Ginsberg (ginsberg) wrote:
> Alvaro (and everyone) -
> 
> I think we can do better than this.
> 
> Prefix-attributes sub-TLV is necessary when a prefix is leaked between levels - and \
> more specifically when leaked upwards in the hierarchy. (We have the "D" bit in the \
> TLV itself when leaked downwards.) 
> While I would prefer that we simplify things and simply require the sub-TLV all the \
> time, I think we can be more generous and still be functional. 
> 1)Prefix-attributes SHOULD be included in Locator TLV
> 2)Prefix-attributes MUST be included when TLV is leaked upwards in the hierarchy
> 3)Prefix-attributes sub-TLV MUST be included when the advertisement is \
> "redistributed" from another protocol 
> Note that because the sub-TLV is not mandatory, if #2 and #3 are NOT followed, \
> receivers will be unable to determine the correct source of the advertisement and \
> may do the "wrong thing". And the receivers will be unable to detect the violation. \
>  Finally, RFC 7794 was published over 5 years ago.
> Vendors make their own choices as to what protocol extensions they choose to \
> support. But given the usefulness of the information in prefix-attributes sub-TLV I \
> would encourage implementations which do not yet support the sub-TLV to add it. 
> Les
> 
> 
> > -----Original Message-----
> > From: Alvaro Retana <aretana.ietf@gmail.com>
> > Sent: Wednesday, May 12, 2021 7:17 AM
> > To: Gengxuesong (Geng Xuesong) <gengxuesong@huawei.com>; Peter
> > Psenak (ppsenak) <ppsenak@cisco.com>; bruno.decraene@orange.com
> > Cc: Van De Velde, Gunter (Nokia - BE/Antwerp)
> > <gunter.van_de_velde@nokia.com>; draft-ietf-lsr-isis-srv6-
> > extensions@ietf.org; Les Ginsberg (ginsberg) <ginsberg@cisco.com>;
> > Shraddha Hegde <shraddha=40juniper.net@dmarc.ietf.org>; lsr@ietf.org;
> > chopps@chopps.org
> > Subject: Re: [Lsr] Last Call: <draft-ietf-lsr-isis-srv6-extensions-14.txt> (IS-IS
> > Extension to Support Segment Routing over IPv6 Dataplane) to Proposed
> > Standard
> > 
> > Peter:
> > 
> > 
> > Hi!
> > 
> > As Xuesong suggested earlier, could you/we live with "SHOULD send"?
> > The mitigating circumstance (recommend vs require) is precisely the
> > lack of support.   I think your original reply to Gunter about how it
> > could be hard to mandate the Flags TLV at this point is spot on.
> > 
> > Thanks!
> > 
> > Alvaro.
> > 
> > 
> > 
> > On May 12, 2021 at 4:49:58 AM, Peter Psenak wrote:
> > 
> > > as I said, if we want to mandate the presence of the Prefix Attribute
> > > sub-TLV, we MUST ignore Locators without it. If we don't, then the MUST
> > > on the originator does not mean anything.
> 
> 

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