Re: [manet] SMF in Manet and MPR

I apologise that I didn't follow too much Manet these last years. As far as I remember the multiple interface MPR stuff with OLSRv2 were assuming that the interfaces were capable to support the topology control traffic, which was supposed to be the sole source of multicast traffic. But if the multicast traffic is demanding significant capacity, there were in the literature some efficient ways to select the MPR according to the demanded QoS. But this supposes that the traffic comes with QoS requirement TLS. 

I hope it helps,

Philippe

----- Mail original -----
De: "Henning Rogge" <hrogge@gmail.com>
À: "manet@ietf.org IETF" <manet@ietf.org>
Envoyé: Lundi 21 Mars 2022 14:06:39
Objet: [manet] SMF in Manet and MPR

Hi,

I am reacting to the talk during the IETF meeting (chat didn't worked
for me for some reason).

My trouble with the MPR optimization for SMF (and a bit with SMF in
general) is that we currently have no good MPR algorithm for
heterogeneous Manet (Manet with multiple different types of radios).

The only described MPR algorithm (OLSRv2 appendix) works separately
for each interface... which means it always selects MPRs on long-range
(and slow) interfaces, which is really not what we want.

Of course there is also the problem that SMF completely ignores
routing metrics... and the problem that we lack a good dataplane for
SMF, which often results in horrible "raw socket trickery"...

So in general I would not suggest to people using SMF because I have
yet to find an use-case where SMF is doing well. Often an
application-specific forwarding strategy is much better than a generic
IP one in terms of multicast in Manet.

Henning Rogge

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