[Olsr-users] IEEE 802.11s

[Aaron Kaplan]

hehe, mailing lsits are so wonderful for creating confusion.

Hehe, Juliusz,


On May 23, 2008, at 6:21 PM, Juliusz Chroboczek wrote:

>> let's get this discussion over and finished please.
>
> I'm sorry to disagree with you, but I like to think that most users of
> OLSR are interested in mesh networking in general, and would want to
> know more about alternate technologies.
>

I am *ver* interested in other techs, believe me. So interested that  
I actively went and visited OLPC in the first place because I was  
interested in the mesh solution they are working on. And they did a  
good job so far. :)
That is the beginning of my personal OLPC involvement - the interest  
in other solutions :)))


>> 1) YES, any properly 802.11s based device will have the possibility
>> to have olsr from olsr.org running on top of it (since it is layer 2
>> and olsr is layer 3)
>

> Done naively, though, this is going to be horribly inefficient.  OLSR
> uses link-layer multicast to flood its routing data, and 802.11s
> implements multicast rather inefficiently.

agreed, that is just what I wrote back to Don in private.
Yes, olsr will get much better when layer 2 info can flow up to layer 3.

>
> Additionally, the link-quality sensing in OLSR is going to yield wrong
> results over 802.11s (any sufficiently dense 802.11s subnet is going
> to appear to have a cost of 1).
>
not wrong, but that is exactly the core of the discussion - since  
802.11s is on layer 2, layer 3 olsr will see it as 1 hop.
Which is *fine*.  But - it will nevertheless calculate lost packets  
(and in the future also bandwidth) for each of those links.
Inefficient? Maybe - can be improved by adding layer 2 infos to layer 3.


> So running OLSR over an IEEE 802.11s network (as opposed to simply
> exporting the 802.11s mesh as an HNA) is going to suck big time.

no, I disagree. It all depends on how much free airtime you have. In  
*any* case!
THe more packets in the air, the worse things are.

>
>> and *end*this*discussion*. It is useless.
>
> (giggle)
>
> One thing to realise is that you should not see 802.11s as the enemy.

please, let's realize that a mailing list is  perfect mechanism for  
creating confusion.
I believe Don did not realize that there is a "natural" intrinsic  
compatability between 802.11s and olsr.org
due to the two layers.

And now you misunderstood me and think that I mislike 802.11s. In  
fact - I like it a lot :)
It has it's place and reasons and it is great stuff. You really just  
need to know and understand what you chose in which situation.


> The main factor slowing down the adoption of mesh technology is the
> centralised ESS model (bunch of wireless APs controlled by a central
> server) promoted by Cisco and friends.  802.11s has a chance of making
> mesh technology popular, which will prompt the move to layer-3 mesh
> networking technologies as the limitations of layer-2 implementations
> become apparent.
>
> Don't take me wrong -- I believe that 802.11s will work great for
> moderate networks.  However, 802.11s requires synchronised
> time-stamps, and it uses a rather inefficient flooding protocol for
> every broadcast/multicast frame (every ARP, every IPv6 ND, every DHCP
> request, every zeroconf announcement).  Furthermore, 802.11s can only
> integrate networks using the IEEE 802.2 frame format -- there's no
> easy way to add, say, a PPP-over-GPRS link to your mesh.
>
> For all of these reasons, I'm doubtful that 802.11s will be useful for
> some kinds of deployments, such as the community networks many of us
> are interested in.  People will try, though, they'll fail, and switch
> to layer 3 technologies.

Exactly! But for a small area network (PANs) where your kitchen sink  
might want to talk to your garden flowering device - 802.11s might be  
the better match.

All I am saying is that there were really some misunderstandings (no  
offense to anyone please! ) in this thread.
I felt a bit tired to repeat the layer 2- layer 3 compatability  
question  a few times.

On the other hand - then maybe I misunderstood y'all folks hehe ;-))


a.