RE: [PATCH v2] mac80211: Jitter HWMP MPATH reply frames to reduce collision on dense networks.

Hi Alexis,

quoted

This is loosely based on RFC5148, specifically event-triggered message
generation as described in section 5.2.

I'm confused. I see how that generally seems to apply to any mobile
network, but it *does* state up-front that
    In some instances, these problems can be solved in these lower
    layers, but in other instances, some help at the network and higher
    layers is necessary.

I believe 802.11 *does* in fact solve these issues at lower layers. Can
you explain how you observed any problem in this area?

Well it certainly attempts to via stuff like carrier sense. But that is not
fool proof and any time two routers hear a frame and both decide to forward
it immediately there is a chance that they will both sense the air at the
same time, decide that it is clear, and lose both their forwarded frames due
to a collision. How often that happens is hard to say but we have observed
that exact behavior a few years ago with an 802.11 multicast routing
protocol and adding jitter significantly improved reliability.

An example of where this would be solved at a lower layer would be something
like a TDMA network that has better mechanisms to ensure that multiple
devices do not send at the same time.

quoted

The frames are not duplicated, but, hopefully offset enough so they
don't collide at the receiver

That wasn't my question - my question regarding duplicating was if this
was
intended to *suppress* duplicates, but it sounds like not.

No, it's not intended to suppress duplicates.

  -- Jesse