Re: [Bier] BIER rechartering

"Dolganow, Andrew (Nokia - SG/Singapore)" <> Wed, 24 January 2018 00:43 UTC

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From: "Dolganow, Andrew (Nokia - SG/Singapore)" <>
To: Alia Atlas <>, "" <>
Thread-Topic: [Bier] BIER rechartering
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Date: Wed, 24 Jan 2018 00:42:56 +0000
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Subject: Re: [Bier] BIER rechartering
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Inline prefixed with ad>

From: BIER <> on behalf of Alia Atlas <>
Date: Wednesday, January 24, 2018 at 10:12 AM
To: "" <>
Subject: [Bier] BIER rechartering

As discussed, I have been working with Tony and Greg on the planned rechartering for the

You can find this version at:

Please send comments.  I want this to make the February 8 IESG telechat.

The BIER (Bit Index Explicit Replication) Working Group has defined
an architecture [RFC 8279] for  multicast forwarding that uses an
encapsulation [RFC 8296] that can be used on MPLS or Ethernet transport.
The BIER-WG is now chartered to produce Standards Track RFCs and to
update or do a Status Change for those RFCs previously published as
Experimental (RFC 8279, RFC 8296, etc.).

First and primarily, the BIER-WG will complete its work on:
  1) Transition Mechanisms: The WG will describe how BIER
     can be partially deployed and still provide useful
     functionality. A minimum of the necessary mechanisms
     to support incremental deployment and/or managing
     different BIER mask-length compatibility may be defined.
     Operation of BIER in non-congruent topologies, i.e.
     topologies where not all routers are BIER capable can
     also be addressed. In addition to tunneling solutions, other
     approaches to make BIER deployable in such environments
     can be worked on. Each such mechanism must include an
     applicability statement to differentiate its necessity from
     other proposed mechanisms.

Ad> I think we want to slightly change that to be less limiting. Not crazy about: can be partially deployed and still provide useful
     functionality. “ would rather say “can be introduced in existing multicast networks to shift multicast delivery either e2e or in part of a network from mechanisms like PIM, ng-MVPN, etc.”

  2) Applicability Statements: The WG will describe how BIER can
     be applied to multicast L3VPN and to EVPN. This draft will
     describe what mechanism is used to communicate the group
     membership between the ingress router and the egress routers,
     what scalability considerations may arise, and any deployment
     considerations. The WG will work on additional applicability
     statements, as needed, describing how BIER can be applied.
  3) Use Case: The WG may produce one use-case document that clearly
     articulates the potential benefits of BIER for different use-cases.
Ad>quite limiting. Why not just say:
Use Case: The WG may continue to augment existing or produce new use-case document(s) that
     articulate the potential benefits of BIER for different use-cases.

  4) Manageability and OAM: The WG will describe how OAM will work in
     a BIER domain and what simplifications BIER offers for managing the
     multicast traffic. A strong preference will be given to extensions to
     existing protocols.
Ad> “A strong preference will be given to extensions to
     existing protocols” – is this not a general IETF rule?

  5) Management models: The WG may work on YANG models and, if needed, MIB
     modules to support common manageability.
Ad> Why not say “The WG will work on defining management APIs to support BIER manageability.”
I think we need a management model(s) but really MIB (unless we want to be last WG that defines SNMP)

  6) IGP extensions. When a BIER domain falls within a "link state IGP"
     network, the information needed to set up the BIER forwarding tables
     (e.g., the mapping between a given bit position and a given egress
     router) may be carried in the link state advertisements of the IGP.
     The link state advertisements may also carry other information related
     to forwarding (e.g., the IGP may support multiple topologies, in which
     case it may be necessary to advertise which topologies are to be used
     for BIER forwarding). Any necessary extensions to the IGP will be
     specified by the WG as Standards Track, in cooperation with the LSR WG.

Ad> Can we say “in co-operation with IETF WGs chartered with IGP protocol ownership”  instead of “in cooperation with the LSR WG”. DO not want to re-charter in case we change/modify/merge/evolve other WGs.

The BIER-WG is additionally chartered to start Standards Track work on:
  7) BIER in IPv6 :  A mechanism to use BIER natively in IPv6 may be
     standardized if coordinated with the 6MAN WG and with understood
     applicability.  Such functionality may focus on assuming software or
     slow-path support first.
Ad> I do not think we should limit unnecessarily the solution or open doors for things that are possible (anything can be done in S/W) but potentially of little value. SO if someone brings a proposal for slow-path BIER we will evaluate on usefulness to use case being solved.

  8) BIER Traffic Engineering:  An architecture for BIER-TE is defined
     in draft-ietf-bier-te-arch; associated fundamental technology is included.
  9) Extensions to support BIER in multi-area IGP Deployments
Ad> should we just merge this with 6 above?


The BIER-WG is chartered to investigate the following topics. The adoption
of any Standards Track drafts will require a milestone approved by the
responsible Area Director.
  10) Novel uses of the BIER bitmap: There are a variety of proposals for
      additional algorithms and other uses of the BIER bitmap and
      encapsulation beyond BIER and BIER-TE.
  11) BIER between Autonomous Domains:   With understood applicability,
      these scenarios may be investigated.
  12) Use of BIER in Controller-based Architectures:  How might controllers
      be used to provide calculated BIRTs and/or BIFTs tables to BFRs?
  13) Applicability of BIER to Applications: The WG may advise on the
      applicability of BIER to various applications.

The BIER-WG will coordinate with several different working groups and
must include the relevant other working groups during working group
last call on the relevant drafts. BIER-WG will coordinate with MPLS-WG
on the associated MPLS-based OAM mechanisms. BIER-WG will coordinate with
LSR-WG on extensions to flood BIER-related information. BIER-WG will
advise BABEL-WG on Babel extensions to support BIER. BIER-WG will
coordinate with BESS-WG and IDR-WG on the applicability of existing
BGP-based mechanisms for providing multicast group membership information.
BIER-WG will coordinate with PIM-WG on the applicability of and extensions
to PIM, IGMP, and MLD to support BIER operations and transition; BIER-WG
will work directly on the applicability statements, as needed.