Re: [Bier] Fwd: New Version Notification for draft-shepherd-bier-standards-track-00.txt

[Greg Shepherd <[e-mail]>]

A few comments inline:

On Wed, Jan 24, 2018 at 4:04 AM, Xiejingrong <[e-mail]> wrote:

>
>
> HI, Chairs Greg, Co-Author Andrew, AD Alia, everyone:
>
>
>
> After three years of hard work, the working group has released two RFCs,
> Architecture(RFC8279) and Encapsulation(RFC8296), which deserve great
> congratulations.
>
> At the same time, I also feel that we still lack APPs / Solutions of using
> BIER to solve customer multicast service requirements.
>
> Should we first take a look at the various Scenario / usecase / solution
> ?  and remove the idealism of kill tree-building protocols ?
>

Please read and comment on the proposed new charter as to whether it is
open to your concerns.


> As <draft-ietf-bier-use-cases> states, protocol simplification is only
> some customer's choice in some Usecase.
>
> As various documents states, the main paradox of traditional multicast
> lies in the hard trade-off, between states caused by the per-flow per-tree,
> and flooding caused by many-flows aggregated in one-tree.
>
> It seems not to be the fault of the tree-building protocol.
>

Tree-state is the problem. A tree building protocol is responsible for that
state. :)


> This draft is a justification before Re-charter, and about the
> descriptions of the tree-building protocol, I would like to raise some
> discussion.
>

As above, please comment on the proposed charter. It seems you are in
agreement that the work is worthy of Standards Track. If so, details of the
justification draft are pointless to discuss. The proposed charter will set
the direction for the WG on the Standards Track. Please take the discussion
there.


>
>
1.  Introduction
>
>
>
>    BIER [RFC8279](Bit Index Explicit Replication) is an alternative      //
>
>    method of multicast forwarding.  It does not require any multicast-
> //XJR1
>
>    specific trees, and hence does not require any multicast-specific
>
>    tree building protocols.  Due to the particular sensitivity of adding
>
>    new significant functionality into the data-plane, the BIER work
>
>    began progress as Experimental.  The current status of the experiment //
>
>    is documented in this draft and is intended to provide justification
>
>    for re-charting the BIER Working Group (WG) as Standards Track and to
>
>    move all published documents of the BIER WG to Standards Track.  This //
>
>    document will detail the benefits, problems, and trade-offs for using
>
>    BIER instead of traditional multicast forwarding mechanisms, as
>
>    required by the BIER WG Charter charter-ietf-bier-01
>
>
>
>    [XJR1]: Yes, BIER is not a tree-building multicast protocol, it does
> not require tree either.
>
>
>
> 2.  IP Multicast Challenges
>
>
>
>    Current IP Multicast solutions require a tree-building control plane //
>
>    to build and maintain end-to-end tree state per flow, impacting
>
>    router state capacity and network convergence times.  Multi-point
> //XJR2
>
>    tree building protocols are often considered complex to deploy and
>
>    debug and may include mechanics from legacy use-cases and/or
>
>    assumptions which no longer apply to the current use-cases.  When
> //XJR3
>
>    multicast services are transiting a provider network through an
>
>    overlay, the core network has a choice to either aggregate customer
>
>    state into a minimum set of core states resulting in flooding traffic
>
>    to unwanted network end-points, or to map per-customer, per-flow tree
>
>    state directly into the provider core state amplifying the network-
>
>    wide state problem.  Though the value proposition of network        //
>
>    replication is high, the cost of deploying IP Multicast is often
>
>    considered too high to justify deployment.
>
>
>
>    [XJR2]: why considered tree-building protocols complex/legacy/no-longer
> apply to current ? that is to say current MVPN are useless ? they not only
> work but also widely deployed!  aren't they ?
>
>    [XJR3]: Agree, per-flow tree is the key. how about Aggregate multi-flow
> but no per-flow tree ?
>
>
>
> 3.  Benefits of BIER
>
>
>
>    BIER is a radical simplification of IP Multicast.  BIER has no tree-
> //XJR4
>
>    building protocol.  BIER has no end-to-end tree/flow state.  BIER has
>
>    no RPF requirements.  BIER packets follow the same path to a
>
>    destination as a unicast packet would take to the same destination.
>
>    BIER provides deterministic convergence times regardless of how many
>
>    (S,G)s are being transported through the BIER network.  BIER can be
>
>    deployed in SDN-driven deployment models, that minimize protocols
>
>    required in a network as well by eliminating multicast protocols and
>
>    relying on IGP infrastructure or direct SDN programmability.
>
>
>
>    [XJR4] BIER has no tree-building protocol, I think it is not a sure
> benefits, but a feature/technology/philosophy. Real benefits is how we get
> a better solution to specific usecase.
>

The BIER WG will be working on use case solutions using BIER. BIER has no
tree-building protocol. If you have a specific use case that needs a tree
building protocol, write a draft and incite discussion in a WG of your
choice or request a BOF.

Thanks,
Greg


>
>
> Thanks.
>
> XieJingrong
>
>
>
>
>
> *From:* BIER [mailto:[e-mail]] *On Behalf Of *Greg Shepherd
> *Sent:* Friday, December 22, 2017 4:56 AM
> *To:* [e-mail]
> *Subject:* [Bier] Fwd: New Version Notification for
> draft-shepherd-bier-standards-track-00.txt
>
>
>
> *,
>
>
>
> Here's our first swing at the Standard Track justification draft.
>
>
>
> Cheers,
>
> Greg
>
>
>
> ---------- Forwarded message ----------
> From: <[e-mail]>
> Date: Thu, Dec 21, 2017 at 12:55 PM
> Subject: New Version Notification for draft-shepherd-bier-standards-
> track-00.txt
> To: Greg Shepherd <[e-mail]>, Andrew Dolganow <
> [e-mail]>
>
>
>
> A new version of I-D, draft-shepherd-bier-standards-track-00.txt
> has been successfully submitted by Greg Shepherd and posted to the
> IETF repository.
>
> Name:           draft-shepherd-bier-standards-track
> Revision:       00
> Title:          Justification for BIER on Standards Track
> Document date:  2017-12-20
> Group:          Individual Submission
> Pages:          6
> URL:            https://www.ietf.org/internet-drafts/draft-shepherd-bier-
> standards-track-00.txt
> Status:         https://datatracker.ietf.org/doc/draft-shepherd-bier-
> standards-track/
> Htmlized:       https://tools.ietf.org/html/draft-shepherd-bier-standards-
> track-00
> Htmlized:       https://datatracker.ietf.org/doc/html/draft-shepherd-bier-
> standards-track-00
>
>
> Abstract:
>    This document is intended to provide justification for re-chartering
>    the BIER Working Group as Standards Track, and to move all BIER WG
>    previously published documents to Standards Track.
>
>
>
>
> Please note that it may take a couple of minutes from the time of
> submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> The IETF Secretariat
>
>
>