[B.A.T.M.A.N.] Batman-adv and routed subnets

[B.A.T.M.A.N.] Batman-adv and routed subnets

[Luca Pretto]

Hi folks,

I really need a bit of your help! I've already spent a week on this and I can't succeed! :(

I'm going to install a small mesh (12 nodes, initially) covering my city and linking some friends of mine.
At the moment the equipment (Ubiquiti) is already installed, structured as AP-STA (PSK2) in one large LAN (all connections bridged L2) with one central dhcp/firewall serving the 192.168.9.0/24 subnet (now that's all inside this net only).

I would like to migrate the topology to a routed network, where the wireless mesh nodes have IPs allocated inside 10.9.0.0/16, and below each one of these nodes there will be a local LAN with reserved subnet (IP offered by OpenWRT through dnsmasq). I've done some experiment with OLSRd and I got a working system that way, but I'd REALLY LOVE to use batman-adv instead.
Some of the networks already have internet connectivity, that will be shared through the mesh to whom needs it.

10.9.11.1 <----> 192.168.11.0/24 --> 192.168.11.1 (internet gateway)
    ||
    ||
10.9.12.1 <----> 192.168.12.0/24
    ||
    ||
10.9.13.1 <----> 192.168.13.0/24 --> 192.168.13.1 (internet gateway)
    ||
    ||
10.9.14.1 <----> 192.168.14.0/24
    ||
    ||
10.9.xx.1 <----> 192.168.xx.0/24

Batman-adv will take care of the routing inside the wireless mesh (links " || " in the diagram).
Anyway, I need that any host on the 192.168.xx.0/24 subnets will be able to talk to each other.

How can this be done with batman-adv?

And then, in your opinion, would be better to stay on BackFire ath9k Open IBSS or is the Attitude Adjustment ath9k RSN IBSS (PtMP) stable enough?

Many many thanks in advance for your time.

Sincerely,
Luca

Re: [B.A.T.M.A.N.] Batman-adv and routed subnets

[Sven Eckelmann]

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On Friday 03 August 2012 11:08:37 Luca Pretto wrote:
> Hi folks,
> 
> I really need a bit of your help! I've already spent a week on this and I
> can't succeed! :(
> 
> I'm going to install a small mesh (12 nodes, initially) covering my city and
> linking some friends of mine. At the moment the equipment (Ubiquiti) is
> already installed, structured as AP-STA (PSK2) in one large LAN (all
> connections bridged L2) with one central dhcp/firewall serving the
> 192.168.9.0/24 subnet (now that's all inside this net only).
> 
> I would like to migrate the topology to a routed network, where the wireless
> mesh nodes have IPs allocated inside 10.9.0.0/16, and below each one of
> these nodes there will be a local LAN with reserved subnet (IP offered by
> OpenWRT through dnsmasq). I've done some experiment with OLSRd and I got a
> working system that way, but I'd REALLY LOVE to use batman-adv instead.
> Some of the networks already have internet connectivity, that will be
> shared through the mesh to whom needs it.
> 
> 10.9.11.1 <----> 192.168.11.0/24 --> 192.168.11.1 (internet gateway)
> 
> 
> 10.9.12.1 <----> 192.168.12.0/24
> 
> 
> 10.9.13.1 <----> 192.168.13.0/24 --> 192.168.13.1 (internet gateway)
> 
> 
> 10.9.14.1 <----> 192.168.14.0/24
> 
> 
> 10.9.xx.1 <----> 192.168.xx.0/24
> 
> Batman-adv will take care of the routing inside the wireless mesh (links "
> || " in the diagram). Anyway, I need that any host on the 192.168.xx.0/24
> subnets will be able to talk to each other.
> 
> How can this be done with batman-adv?

First thing: batman-adv doesn't route (as in l3 routing). batman-adv creates a 
distributed switch on l2 (so, batman-adv does path finding). Therefore, 
batman-adv doesn't care about the l3 stuff.

And the stuff you've mentioned above is l3 stuff. So out of scope for batman-
adv. Either you create static routes, use proxy arp or use another software 
that distributes the l3 routes.

Kind regards,
	Sven

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Re: [B.A.T.M.A.N.] Batman-adv and routed subnets

[Luca Pretto]

Thanks for your answer Sven.

So, I've obviously misunderstood the part "mixing non-B.A.T.M.A.N. systems with batman-adv" [&]
I admit: the fact that batman-adv operates al L2 really confuses me a lot!
I'm a DIY nerd with no background training, so it's quite difficult to me.. But I won't give up! ;D

So, do you think that I should try to setup OSPF on every node, to keep the thing as-much-auto-scaling-as-possible?

But in that case I suspect I won't be able to use the "Gateway support" functions. Is it correct? [%]

Have a nice day,
Luca

[&] http://www.open-mesh.org/projects/batman-adv/wiki/Quick-start-guide
[%] http://www.open-mesh.org/projects/batman-adv/wiki/Gateways

Il giorno 03/ago/2012, alle ore 11:22, Sven Eckelmann ha scritto:

> First thing: batman-adv doesn't route (as in l3 routing). batman-adv creates a 
> distributed switch on l2 (so, batman-adv does path finding). Therefore, 
> batman-adv doesn't care about the l3 stuff.
> 
> And the stuff you've mentioned above is l3 stuff. So out of scope for batman-
> adv. Either you create static routes, use proxy arp or use another software 
> that distributes the l3 routes.
> 
> Kind regards,
> 	Sven

Re: [B.A.T.M.A.N.] Batman-adv and routed subnets

[Sven Eckelmann]

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On Friday 03 August 2012 11:40:43 Luca Pretto wrote:
> Thanks for your answer Sven.
> 
> So, I've obviously misunderstood the part "mixing non-B.A.T.M.A.N. systems
> with batman-adv" [&]

This thing only explains how to connect non-batman-adv systems like you would 
to with a switch... not routing.

> I admit: the fact that batman-adv operates al L2
> really confuses me a lot! I'm a DIY nerd with no background training, so
> it's quite difficult to me.. But I won't give up! ;D

Just imagine that the mesh is a big switch. Such a thing that you have 
(propably) on your table. This version is not in one box, but build using 
connected small boxes. It depends on you how you want to give clients access 
to this switched network... just use L2 switches/bridges to connect them or 
use L3 routing to create smaller broadcast domains.

> So, do you think that I should try to setup OSPF on every node, to keep the
> thing as-much-auto-scaling-as-possible?

Sry, will leave that open for someone else.

> But in that case I suspect I won't be able to use the "Gateway support"
> functions. Is it correct? [%]

The gateway support stuff is just for DHCP routing. It helps sent a DHCP 
packet to the best gateway. And your setup (that routes packets) will not sent 
DHCP packets from clients over the mesh, but instead each router has to answer 
it. So yes, normal L3 setups will not benefit from the gateway support. You 
may still use it when you configure the dhcp server on the routers as dhcp-
relay-agent (but only when they still forward the request as broadcast and not 
as unicast to a preconfigured server).

Kind regards,
	Sven

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Re: [B.A.T.M.A.N.] Batman-adv and routed subnets

[Simon Wunderlich]

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Hey Luca,

On Fri, Aug 03, 2012 at 11:40:43AM +0200, Luca Pretto wrote:
> Thanks for your answer Sven.
> 
> So, I've obviously misunderstood the part "mixing non-B.A.T.M.A.N. systems with batman-adv" [&]
> I admit: the fact that batman-adv operates al L2 really confuses me a lot!
> I'm a DIY nerd with no background training, so it's quite difficult to me.. But I won't give up! ;D
> 

Sven explained it already ... just think of batman-adv as a big, distributed switch with some nice
extras. ;)

> So, do you think that I should try to setup OSPF on every node, to keep the thing as-much-auto-scaling-as-possible?

from your description, you want to have some smaller subnets, and use batman-adv for the backbone
to interconnect them. That's a fine approach, and you can use any routing technology on top (quagga with
OSPF/BGP, olsr, babel, ...) to announce the networks. Whatever seems most suitable for you. :)

> 
> But in that case I suspect I won't be able to use the "Gateway support" functions. Is it correct? [%]

The gateway support is just for sending DHCP packets to the "best" gateway, and this gateway
is selected by batman-adv. But this won't work for you, because the users will get the DHCP leases
from their local DHCP server responsible for the network. So this feature won't help you as long
as you are subnetting.

The idea of the gateway feature is that you have multiple DHCP servers which are serving
as router for their respective internet connection, e.g.:

 * router A serves subnet 10.9.1.0/24
 * router B serves subnet 10.9.2.0/24
 * router C serves subnet 10.9.3.0/24
 * some more routers don't act as a DHCP server as they don't have an Internet uplink

Then, you'd just bridge all APs so that users DHCP requests will end up in the mesh at one of the
DHCP servers - and the gateway feature will make sure that it's the DHCP server with the best
connection quality. ;)

OTOH, subnetting has it's plus side as well if you want to seperate the APs somehow or limit
the broadcast scope. Also on very large networks I'd recommend to use subnets or smaller mesh
islands.

Cheers,
	Simon

> 
> Have a nice day,
> Luca
> 
> [&] http://www.open-mesh.org/projects/batman-adv/wiki/Quick-start-guide
> [%] http://www.open-mesh.org/projects/batman-adv/wiki/Gateways
> 
> Il giorno 03/ago/2012, alle ore 11:22, Sven Eckelmann ha scritto:
> 
> > First thing: batman-adv doesn't route (as in l3 routing). batman-adv creates a 
> > distributed switch on l2 (so, batman-adv does path finding). Therefore, 
> > batman-adv doesn't care about the l3 stuff.
> > 
> > And the stuff you've mentioned above is l3 stuff. So out of scope for batman-
> > adv. Either you create static routes, use proxy arp or use another software 
> > that distributes the l3 routes.
> > 
> > Kind regards,
> > 	Sven
> 
> 

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