Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-isis-mpls-elc-12: (with DISCUSS and COMMENT)
Peter Psenak <ppsenak@cisco.com> Thu, 21 May 2020 12:15 UTC
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To: Alvaro Retana <aretana.ietf@gmail.com>, Benjamin Kaduk <kaduk@mit.edu>, The IESG <iesg@ietf.org>
Cc: Acee Lindem <acee@cisco.com>, draft-ietf-isis-mpls-elc@ietf.org, lsr-chairs@ietf.org, lsr@ietf.org
References: <158992828112.6026.1646593855480055081@ietfa.amsl.com> <1242ad52-bb48-8526-b65b-d413e0cd9e25@cisco.com> <CAMMESsz3esEVMBgaPZQd3bUQG9-t5=vG6W3_P0rDZ51Ua25hRw@mail.gmail.com>
From: Peter Psenak <ppsenak@cisco.com>
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Date: Thu, 21 May 2020 14:15:37 +0200
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Subject: Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-isis-mpls-elc-12: (with DISCUSS and COMMENT)
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Hi Alvaro, On 21/05/2020 13:44, Alvaro Retana wrote: > On May 21, 2020 at 6:05:41 AM, Peter Psenak wrote: > > > Peter: > > Hi! > > >>> ---------------------------------------------------------------------- >>> DISCUSS: >>> ---------------------------------------------------------------------- >>> >>> As for other reviewers, many of my comments duplicate those for the OSPF >>> document; I expect that the analogous responses apply and am fine if >>> they only appear for one document's review. >>> >>> Here, the question I have about normative language applies to the text >>> in Section 3: >>> >>> When a router propagates a prefix between ISIS levels ([RFC5302], it >>> MUST preserve the ELC signaling for this prefix. >>> >>> The scenario in question is analogous to the OSPF cross-area case: is >>> the router propagating the prefix between ISIS levels required to >>> implement this document; is preservation of the flag value a new >>> requirement from this document vs. a preexisting property; and is this >>> document trying to make normative requirements of devices that don't >>> implement this document? >> >> ##PP >> this is a new requirement and only applies to the routers that support >> this document. We are not making normative requirements of devices that >> don't implement this document, we cannot. >> >> Maybe we can add that it only applies to the routers that supports this >> extension: >> >> "When a router supporting this extension propagates a prefix between >> ISIS levels ([RFC5302], it MUST preserve the ELC signaling for this prefix." >> >> Would it work? > > > You're right, we can only apply requirements to routers that support > this specification. IOW, adding the clarification is not necessary. > > > My interpretation of Ben's question is two-fold: > > (1) Would ISIS routers normally propagate the information to a > different level? The ELC is a new prefix attribute flag -- are prefix > attributes always propagated (unchanged) to other levels? If so, then > the requirement (MUST) is not needed. My reading of rfc7794 is that > the propagation is optional... depends on the attribute or a bit. Some are propagated some are not. That's why we are saying this one MUST be preserved. > > (2) If the propagation is not automatic, and the L1L2 router doesn't > support this specification, then what are the drawbacks/failure > scenarios? IOW, for multi-level operation is it a requirement that > the L1L2 support this specification? drawback are identical to what is mentioned in the Security Considerations section. thanks, Peter > > > Thanks! > > Alvaro. > >
- [Lsr] Benjamin Kaduk's Discuss on draft-ietf-isis… Benjamin Kaduk via Datatracker
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Peter Psenak
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Alvaro Retana
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Peter Psenak
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Benjamin Kaduk
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Alvaro Retana
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Peter Psenak
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Peter Psenak
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Acee Lindem (acee)
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Peter Psenak
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Acee Lindem (acee)
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Acee Lindem (acee)
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Peter Psenak
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Acee Lindem (acee)
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Alvaro Retana
- Re: [Lsr] Benjamin Kaduk's Discuss on draft-ietf-… Benjamin Kaduk