Re: [Bier] RFC8279: Request for authors to update RFC
Toerless Eckert <tte@cs.fau.de> Mon, 28 June 2021 23:22 UTC
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Date: Tue, 29 Jun 2021 01:22:17 +0200
From: Toerless Eckert <tte@cs.fau.de>
To: Greg Shepherd <gjshep@gmail.com>
Cc: BIER WG <bier@ietf.org>
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Subject: Re: [Bier] RFC8279: Request for authors to update RFC
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Thanks, Greg. Would be great if any work towards bis'ing the RFC would be set up openy enough such that this type of help/support will continue to be possible (e.g.: if there is a DT style approach, pls. make it open). Cheers toerless On Mon, Jun 28, 2021 at 10:40:29AM -0700, Greg Shepherd wrote: > Thanks Toerless. All good suggestions, and valuable input. I'm certain > Sandy will welcome your help. > > Cheers, > Greg > > On Tue, Jun 22, 2021 at 3:29 AM Toerless Eckert <tte@cs.fau.de> wrote: > > > Greg, *: > > > > I would like to help,... but better not promise more than best effort > > cycles, which may be rare > > under presence of more businss criticial cycles. > > > > I am not quite clear yet, what specifically would be in our out of scope > > of such > > an rfc8279bis? effort. I remember that when we updated PIM-SM for its 'bis > > RFCs, > > someone had collected a long list of issues/improvement suggestions. Maybe > > we should have a wiki page on the ietf BIER wiki to allow WG members to > > contribute > > suggestions for improvements to make it easier to track possible work > > items ? > > > > Working through bier-te-arch for updating to ADs review last weeks, i > > revisited > > some parts of 8279 to better align with them, so some thoughts to help > > such a list somewhat cenric to that: > > > > 1. Pictures! > > > > Section 4 might benefit from a picture visualizing the layerin, > > maybe the picture in bier-te-arch could serve as a starting point. > > > > 2. Explicitly call out control vs. forwarding plane > > > > Section 4.2 does not explicitly distinguish between what of its bullet > > point list is BIER layer control plane vs. BIER layer forwarding plane. > > Maybe separating would be nice. > > > > 3. distributed vs. decentralized/centralized BIER layer control plane > > > > The whole document is written (IMHO) so as to imply that the control > > plane > > is distributed. This is definitely what we defined so far in the WG > > (with ISIS, OSPF), and IMHO the biggest benefit of BIER compared > > to e.g.: BIER-TE which because of its need to engineer the trees > > more naturally depends on a controller. > > > > Nevertheless, i remember Tony and others to reiterate in past meetings > > that we could > > also build/implement BIER purely with controller driven conrol plane. > > If it is indeed a goal to open hat door, than such an option might be > > better documented. > > > > Example of text that seems to exclude a solely controller based BIER > > layer control plane: > > > > (4.2) "Protocols and procedures that a given BFR uses to advertise, to > > all other BFRs in the same BIER domain" > > > > 4. Need for / Role of BIRTs > > > > If controller driven BIER is of interest, IMHO, one corollary is that > > the BIRTs may be optional, because the way i see it, they really are > > the data structure populated by the local control plane (IGP/BGP), > > whereas > > a controller based control plane may be beter off directly populating > > the BIFTs. I think it might be easier though to add such thoughts to > > the architecture when we have worked through such thoughts by being > > further along with the BIER yang models (i already tried to help with > > the object model for the BIRT there, i don't think we have even tried > > to define the real BIFT entries in the yang model). > > > > aka: like in unicast/ip-multicast, BIRT to me would live solidly > > in the BIER layer control plane, required maybe only with distributed > > control plane options, whereas he BIFT is the control plane API into > > the BIER layer > > forwarding plane, aka: mandatory for any BIER forwarder). > > > > 5. Acceptable F-BM for BIFT (impacts implementations) > > > > If/when we define any yang model for the BIFT, IMHO we would need to > > resolve the question if/what F-BM would have to be acceptable via such > > an API. This would have an impact on the forwarding implementations. > > > > See slide 8 of my IETF103 preso ( > > https://slidetodoc.com/biertearch-ietf-103-bangkok-draftietfbiertearch01-toerless-eckert-ttecs/ > > , https://www.youtube.com/watch?v=UBZY4H6Ql_I&t=13s at 1:31:00 ) > > > > 6. Which layer does the IGP live in ? > > > > One of the corollaries not explicitly called out for in 8279 is that > > AFAIK, the IGP itself seems to live in the conrol plane of the routing > > underlay, whereas the BIER extensions of the IGP would live in the > > control plane of the BIER layer. > > > > Aka: the fact that a single control plane (IGP) protocol may stretch > > across > > the layers of the BIER architecture may be something to explicitly call > > out, > > because this may be somewhat counterintuitive to readers oherwise. > > > > 6. API between Flow overlay and BIER layer on BFIR and BFER > > > > If/when we wanted to ensure that Flow overlay and BIER layer could be > > developed independendly on BFIR/BFER (think linux where BIER is > > implemented > > once and different apps/overlays want to use it), we may want to have a > > somewhat more formalized abstract API definition for the BIER layer. > > > > Thought experiment: I build on linux BFIR/BFER some flow overlay based > > on > > an available MPLS based BIER layer implementation. Then comes along > > draft-ietf-bier-non-mpls-bift-encoding an the BIER layer is extended to > > support e.g. BIER directly over ethernet. Q: should/could we have > > defined upfront the BIER-layer to flow overlay API such that i would not > > have to go back updating/modifying the flow overlay implementation ? > > I think that would be lovely. Have we given implementers all the help we > > shuold to enable that ? > > > > This goes primarily back to do we expose BIFT-id to flow overlay, > > and what happens if such in hat draft its semantic changes. > > > > Cheers > > Toerless > > > > On Sat, Jun 12, 2021 at 06:05:16AM -0700, Greg Shepherd wrote: > > > A big "thank you" to all WG members who have worked so hard to get BIER > > to > > > where it is today. And to no surprise, our work is not done. The > > following > > > bullet points are from the Chairs' technical summary previously sent to > > the > > > list: > > > > > > ??? BIER encoding is specified in RFC8296 > > > ??? Alia Atlas: ???IANA code-points don???t change. This is the reason > > why BIER > > > began as experimental - narrow > > > point in hourglass??? > > > ??? The encoding at the ???narrow point of the hourglass??? ??? the > > forwarding > > > plane ??? is the foundation from which > > > the rest of the architecture grows. > > > ??? This was the position of the IESG and the BIER WG ADs at the time of > > the > > > original WG Experimental Charter. > > > ??? This is admittedly historic/institutional knowledge of those > > involved in > > > the WG from the beginning. But it is also > > > a core tenet of the layered and scalable architecture of the > > > Internet and was erroneously assumed as > > > well-understood by the original WG contributors. The WG needs to > > > update the BIER architecture to make this > > > responsibility clear for all future contributors. > > > > > > RFC8279 began as a draft at the very beginning of the WG. It has since > > been > > > made clear that the authors at that time had assumed the importance of > > the > > > forwarding plane as the foundation of architecture was well understood by > > > the community at large. That no longer seems to be the case. > > Additionally, > > > the draft of RFC8279 began before the draft of RFC8296 was complete, and > > > even before the assignment of the IEEE BIER ethertype. > > > > > > This is a call for volunteers to update RFC8279 to better define BIER at > > > the forwarding plane, and clarify how IETF-standard encapsulation > > > mechanisms can be used to transit BIER packets, while preserving the core > > > tenet of a layered and scalable architecture of the Internet. > > > > > > If you would like to tackle this update, please reply to this thread. > > > > > > Thanks, > > > Greg > > > (Chairs) > > > > > _______________________________________________ > > > BIER mailing list > > > BIER@ietf.org > > > https://www.ietf.org/mailman/listinfo/bier > > > > > > -- > > --- > > tte@cs.fau.de > > -- --- tte@cs.fau.de
- [Bier] RFC8279: Request for authors to update RFC Greg Shepherd
- Re: [Bier] RFC8279: Request for authors to update… zhang.zheng
- Re: [Bier] RFC8279: Request for authors to update… Greg Shepherd
- Re: [Bier] RFC8279: Request for authors to update… Bidgoli, Hooman (Nokia - CA/Ottawa)
- Re: [Bier] RFC8279: Request for authors to update… Tony Przygienda
- Re: [Bier] RFC8279: Request for authors to update… Greg Shepherd
- Re: [Bier] RFC8279: Request for authors to update… Jeffrey (Zhaohui) Zhang
- Re: [Bier] RFC8279: Request for authors to update… Bidgoli, Hooman (Nokia - CA/Ottawa)
- Re: [Bier] RFC8279: Request for authors to update… Gyan Mishra
- Re: [Bier] RFC8279: Request for authors to update… Greg Shepherd
- Re: [Bier] RFC8279: Request for authors to update… Toerless Eckert
- Re: [Bier] RFC8279: Request for authors to update… Aijun Wang
- Re: [Bier] RFC8279: Request for authors to update… Greg Shepherd
- Re: [Bier] RFC8279: Request for authors to update… Toerless Eckert
- Re: [Bier] RFC8279: Request for authors to update… 'Toerless Eckert'
- Re: [Bier] RFC8279: Request for authors to update… zhang.zheng
- Re: [Bier] RFC8279: Request for authors to update… Mankamana Mishra (mankamis)