Subject: [pim] Minor technical change in pop-count

From: Stig Venaas <[email-masked]>
Date: Fri, 16 Nov 2012 09:54:53 -0800

During AUTH48 for draft-ietf-pim-pop-count-07.txt I realized one minor
technical issue that I would like to address. Since this is a technical
change, I would like to see if anyone in the WG has any concerns.

We got two flags regarding tunneling defined as follows:

       t flag:  This flag is set if there are any tunnels on the
          distribution tree.  If a tunnel is in the oif-list, a router
          should set this bit in its Join/Prune messages.  Otherwise, it
          propagates the bit setting from downstream joiners.

       a flag:  This flag is set if there are any auto-tunnels on the
          distribution tree.  If an auto-tunnel is in the oif-list, a
          router should set this bit in its Join/Prune messages.
          Otherwise, it propagates the bit setting from downstream
          joiners.  An example of an auto-tunnel is a tunnel set up by
          the Automatic Multicast Tunneling [AMT] protocol.

It is not clear whether the "t" flag applies to all tunnels or all
tunnels except auto-tunnels. Or rather, by reading the description of
"t" by itself it would seem obvious that it is all tunnels, but the
fact that there is a separate flag for auto-tunnels makes it seem more
reasonable that the two flags are for disjoint types of tunnels.

I would like to change the description of "t" slightly to talk about
manually configured tunnels. How about this text:

       t flag:  This flag is set if there are any manually configured
          tunnels on the distribution tree. This means any tunnel that
          is not an auto-tunnel.  If a tunnel is in the oif-list, a
          router should set this bit in its Join/Prune messages.
          Otherwise, it propagates the bit setting from downstream
          joiners.

I hope you agree this is reasonable. There is no point in having the
flags overlap. If we want to check if any type of tunneling is
involved, we just check if either of the flags are set.

Stig

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From: John William Atwood <[email-masked]>
Date: Fri, 16 Nov 2012 13:30:53 -0500

Stig,

I agree that the disjoint specification is better.

I would add two words to the proposed definition---see inline for where.

  Bill

>          is not an auto-tunnel.  If a tunnel is in the oif-list, a
                                       ^manually configured
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> pim mailing list
> [email-masked]
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-- 
Dr. J.W. Atwood, Eng.             tel:   +1 (514) 848-2424 x3046
Distinguished Professor Emeritus  fax:   +1 (514) 848-2830
Department of Computer Science
   and Software Engineering
Concordia University EV 3.185     email:[email-masked]
1455 de Maisonneuve Blvd. West    http://users.encs.concordia.ca/~bill
Montreal, Quebec Canada H3G 1M8

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From: Stig Venaas <[email-masked]>
Date: Fri, 16 Nov 2012 10:44:30 -0800

>>           is not an auto-tunnel.  If a tunnel is in the oif-list, a

Great catch! I'm suggesting the below text to the RFC Editor then. We'll
wait and see for a few days if there are any objections though.

       t flag:  This flag is set if there are any manually configured
          tunnels on the distribution tree. This means any tunnel that
          is not an auto-tunnel.  If a manually configured tunnel is in
          the oif-list, a router sets this bit in its Join/Prune
          messages. Otherwise, it propagates the bit setting from
          downstream joiners.

      a flag:  This flag is set if there are any auto-tunnels on the
          distribution tree.  If an auto-tunnel is in the oif-list, a
          router sets this bit in its Join/Prune messages. Otherwise, it
          propagates the bit setting from downstream joiners.  An
          example of an auto-tunnel is a tunnel set up by the Automatic
          Multicast Tunneling [AMT] protocol.

Stig