Re: [Isis-wg] [Bier] WGLC : draft-ietf-bier-isis-extensions-07.txt

"IJsbrand Wijnands (iwijnand)" <> Thu, 15 February 2018 08:11 UTC

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From: "IJsbrand Wijnands (iwijnand)" <>
To: Jeff Tantsura <>
CC: "Acee Lindem (acee)" <>, Xiejingrong <>, "" <>, "" <>, "" <>, "Dolganow, Andrew (Nokia - SG/Singapore)" <>
Thread-Topic: [Bier] WGLC : draft-ietf-bier-isis-extensions-07.txt
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Date: Thu, 15 Feb 2018 08:11:44 +0000
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Subject: Re: [Isis-wg] [Bier] WGLC : draft-ietf-bier-isis-extensions-07.txt
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Hi Folks,

I support 16 bits because of the following reasons.

For me it would make sense to align the Algorithm value to the "IGP Algorithm" registry. This registry is defined in:

In my opinion, this is going to cover 90% of the use-cases because BIER is defined to run over a unicast underlay, so what ever is done for Unicast, it will work for BIER automatically (like Flex Algo), and avoids to duplicate registries. However, this registry is also 8 bits. That means there is no room for anything else and I already know there are different options about this.

To avoid an other long debate/fight over these 8 bits, lets get more bits now so we don't corner our selfs. Its a minor change to the draft.

Lets not start a debate now on how BAR is used, as I'm sure we will not reach agreement  in time and we're gonna delay the IGP drafts. We can start a discussion after the IGP draft are through and what all the use-cases are we need to cover. I already look forward to those discussions :-)



Sent from my iPad

On 15 Feb 2018, at 07:24, Jeff Tantsura <<>> wrote:


I’d really like to see justification for anything larger than 8 bits.


On Feb 14, 2018, at 18:30, Acee Lindem (acee) <<>> wrote:

I agree. As a point of reference, we've only have defined two IGP algorithms so far and the segment routing draft dates back about 4 years.

Even with more artistic freedom afforded to multicast,  I still believe 256 standard algorithms are enough.


On 2/14/18, 9:15 PM, "BIER on behalf of Dolganow, Andrew (Nokia - SG/Singapore)" <<> on behalf of<>> wrote:


  I would think 8 bits are sufficient. Others (like SegRtg mentioned below also use 8). 8 bits gives us tons of room to grow - especially since we have only a single value defined currently (SFP 0). If we have clear use cases that show us running out of 8 bits or getting close to that we can/should discuss and evaluate extensions in light of that but increasing the space "just in case" is not a prudent way to go.


  -----Original Message-----
  From: BIER <<>> on behalf of Xiejingrong <<>>
  Date: Wednesday, February 14, 2018 at 5:06 PM
  To: Arkadiy Gulko <<>>, "<>" <<>>, "<>" <<>>
  Subject: Re: [Bier] WGLC : draft-ietf-bier-isis-extensions-07.txt

      Hi Arkadiy,

      I checked the latest <draft-ietf-ospf-segment-routing-extensions-24> and <draft-ietf-isis-segment-routing-extensions-15> for reference and comparing, and they both use a 8 bits Algorithm.
      One of the description: "Algorithm: Single octet identifying the algorithm."

      Interesting to use more than 8 bits for BIER's future flexibility :-)


      -----Original Message-----
      From: BIER [] On Behalf Of<>
      Sent: Wednesday, February 14, 2018 8:42 AM
      Subject: [Bier] WGLC : draft-ietf-bier-isis-extensions-07.txt

      Hello Working Group,
      After initial discussions between multiple participants of the working group, we consolidated that BIER's future flexibility would be well served if we extend the IGP signaling BAR field to 16 bits. We are currently reviewing various use-cases that can greatly benefit from this enhancement.
      I would appreciate if the proposed change could be considered as part of IETF Last Call review.

      -----Original Message-----
      From: BIER [] On Behalf Of<>
      Sent: Friday, February 09, 2018 5:11 PM
      Subject: [Bier] I-D Action: draft-ietf-bier-isis-extensions-07.txt

      A New Internet-Draft is available from the on-line Internet-Drafts directories.
      This draft is a work item of the Bit Indexed Explicit Replication WG of the IETF.

              Title           : BIER support via ISIS
              Authors         : Les Ginsberg
                                Tony Przygienda
                                Sam Aldrin
                                Jeffrey (Zhaohui) Zhang
          Filename        : draft-ietf-bier-isis-extensions-07.txt
          Pages           : 10
          Date            : 2018-02-09

         Specification of an ISIS extension to support BIER domains and sub-

      The IETF datatracker status page for this draft is:

      There are also htmlized versions available at:

      A diff from the previous version is available at:

      Please note that it may take a couple of minutes from the time of submission until the htmlized version and diff are available at<>.

      Internet-Drafts are also available by anonymous FTP at:

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