Re: [manet] SMF in Manet and MPR

[Henning Rogge <[e-mail]>]

On Mon, Mar 21, 2022 at 7:17 PM Christopher Dearlove
<[e-mail]> wrote:
> This depends on how you set up your link metrics. Flooding MPRs have
> the option to use or not use link metrics. But if your interfaces are different
> enough that you’d rather use multiple hops on a better interface rather
> than fewer hops on a poorer interface, then you should be using link metrics.
> If you aren’t, you will have problems. (They probably show up even faster
> with routing.)

I don't think metrics can resolve my problem. The problem arises from
calculating the MPRs just from the 2-hop neighborhood.

Let me sketch the problem.... imagine you have a Mesh with both VHF
(slow long range) and UHR (fast short range) radios.

Now imagine your router R has a neighbor A on VHF, which is two-hop
reachable on UHF... if A also has a neighbor even further away, A will
ALWAYS be a MPR, because the neighbor of A is at least three hops away
over UHV.

Unicast routes will still flow over the UHF network, but flooding will
be done over VHF, which is a problem.

> And so the problem here is with that SMF predates link metrics, and hasn’t
> been updated. It was even worse when I - and others - tried multicasting
> by intercepting packets in the stack, wrapping them up as a new OLSR (v1)
> message type and reinjecting into UDP (OLSR port), plus the reverse at
> reception. Fun days.

The OLSR implementation from olsr.org has something like this called
BMF... it was a disaster. ^^

Henning Rogge