Michael Richardson <> Tue, 28 April 2020 02:54 UTC

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From: Michael Richardson <>
To: "Joel M. Halpern" <>
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Date: Mon, 27 Apr 2020 22:54:21 -0400
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Joel M. Halpern <> wrote:
    > I suspect that for most GRASP purposes, even if there is a layer 2 network
    > between the parties,  we are not much worried about how LAG handles GRASP
    > packets?   If we care about that, then the source port should be randomized
    > between flows, and stable for sequences of related messages.

The idea being that the different 5-tuples would wind up on different links
of the LAG, correct?

Brian E Carpenter <> wrote:
    > I think we don't care, because GRASP traffic density should be quite
    > modest so load balancing isn't really an issue. In response to Michael,
    > I don't think the source port matters at all for M_FLOOD messages. My
    > code uses the o/s default, but it has no significance to the
    > recipient.

I agree with Brian: the DULL message is basically just a probe sent every few
seconds.  The bulk traffic would run over IPsec, so there will be an ESP SPI#.
How would a LAG flow balancer deal with that?  I don't think it would balance
at all unless two SAs were negotiated.  I think that the flow header could
also be tweaked in some kind of round robin fashion.

But, if it's a MC-LAG, then the ACP really wants to see both chassis
seperately.  So it occurs to me that we could hack LACP rather than LLDP :-)
It appears that it uses a specific multicast destination.

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