Re: [Anima] ACP -10 [was Re: I-D Action: draft-ietf-anima-autonomic-control-plane-08.txt]

Michael Richardson <> Mon, 25 September 2017 13:44 UTC

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From: Michael Richardson <>
To: Brian E Carpenter <>
cc: Toerless Eckert <>,,
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Date: Mon, 25 Sep 2017 09:44:22 -0400
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Subject: Re: [Anima] ACP -10 [was Re: I-D Action: draft-ietf-anima-autonomic-control-plane-08.txt]
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Brian E Carpenter <> wrote:
    >> Given that, one will expect to see the same M_FLOOD from the same sender via
    >> multiple paths.  That's fine, and I think it's good.  But, comparing them is
    >> kind of meaningless, because once you find out who the sender is, the unicast
    >> routing takes over, and you will take the unicast direction only.
    >> If one hears announcements from multiple senders, then there might be
    >> different directions, but the TTL you see in the M_FLOOD may have NOTHING to
    >> do with what the unicast cost is.

    > True, in a general topology - the LL multicasts combined with GRASP relaying
    > will ammount to a spanning tree rooted at the M_FLOOD sender, but the unicast
    > paths will be set by RPL. There's no reason they will be congruent. They might
    > be. This is a good point!

As an example, take any ring-like metro-ethernet architecture that an ISP
might deploy.  They have multiple redundant paths across the network, and
they use them for customer data... there is a lot of work going to balance
traffic across such structures.

On top of that, impose a strict DODAG structure with the NOC as the root, and
one can see that ACP traffic between adjacent nodes on a metro-ethernet ring
may well travel all the way to the DODAG root and down again, while an
M_FLOOD will travel sideways.

Michael Richardson <>, Sandelman Software Works
 -= IPv6 IoT consulting =-