[B.A.T.M.A.N.] Batman advanced and internet gateways

[B.A.T.M.A.N.] Batman advanced and internet gateways

[Clemens John]

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Hi,

I know I asked this question some time ago but I didn´t got it till now so I 
have to ask again.
I know that Batman advanced does the meshing on layer 2 and has nothing to do 
with layer 3.

We have a wonderfull working Batman advanced network now which we use with 
IPv4.
Communication inside the networks works verry well and everything is fine.

Now I want to go from the Batman advanced mesh network to the internet. 
Therefor we have several gateways which I can use to get into the internet.
To use one of the gateways, I only have to set the default route of the mesh-
client to the gateways IPv4 address.

How can I do this automatically and how can I automatically choose the best 
gateway for my client? I know that Batman advanced does not do this for now 
but I already saw something that sounded like made for this in the trunk 
version and on the manpage of batctl. The function is called gw_mode.

*How do you this?
*What do you recommend for this task?
*What´s about the funktion in trunk? Is the function made for this?
**If so why do you mix Layer 2 and Layer 3 now?
**When do you think this function will be in the stable release?

Sorry for so many questions but I´m a bit confused^^
Clemens

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Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Marek Lindner]

Hi,

> I know I asked this question some time ago but I didn´t got it till now so
> I have to ask again.

some mails get lost in this stream, so just keep bothering us until you have 
your answers. :)


> How can I do this automatically and how can I automatically choose the best
> gateway for my client? I know that Batman advanced does not do this for now
> but I already saw something that sounded like made for this in the trunk
> version and on the manpage of batctl. The function is called gw_mode.

Yes, there is such a functionality. The online manpage shows the version of 
the trunk.


> *How do you this?
> *What do you recommend for this task?
> *What´s about the funktion in trunk? Is the function made for this?

It requires each gateway to have a DHCP server running. The clients will 
select their gateway and relay the dhcp requests via unicast to the selected 
gateway only.
You only need to activate the gateway / client mode and have a dhcp server 
running. 


> **If so why do you mix Layer 2 and Layer 3 now?

If you don't want to mix layer2 / layer3 then just don't use this feature. It 
is disabled per default.
If you have a better idea how to handle multiple gateways in a layer2 mesh we 
are very open to your suggestions. :)


> **When do you think this function will be in the stable release?

Unfortunately, we did not get around finishing it to the point that we feel 
comfortable with releasing this feature. I think the trunk is quite stable but 
still lacks some things. E.g. blacklisting / whitelisting gateways, IPv6, etc. 

Regards,
Marek

Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Clemens John]

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Am Dienstag 06 Juli 2010, 22:15:45 schrieb Marek Lindner:
> It requires each gateway to have a DHCP server running. The clients will
> select their gateway and relay the dhcp requests via unicast to the
> selected gateway only.
> You only need to activate the gateway / client mode and have a dhcp server
> running.

Okay I did this but I have some questions left:

Does the DHCP server on the gateway need to distribute IP-Adresses?
If so I think they have to be distributet on the batman interface right?

Does the Batman advanced interface on the clients need to request an IP-Adress 
from the DHCP server or can I also set a static IP adress?

If the clients need to request an IP adress from the DHCP server, where is the 
difference between requesting an IP without Batman advanced and with Batman 
advanced? Does Batman advanced say from wich server to request the IP or which 
default route to choose?

> 
> > **If so why do you mix Layer 2 and Layer 3 now?
> 
> If you don't want to mix layer2 / layer3 then just don't use this feature.
> It is disabled per default.
> If you have a better idea how to handle multiple gateways in a layer2 mesh
> we are very open to your suggestions. :)

Sry for this question we just discussed this on the last community meeting and 
somebody wondered if this is the most beautiful way. Maybe it´s not but you 
are right there is no other way.

> Unfortunately, we did not get around finishing it to the point that we feel
> comfortable with releasing this feature. I think the trunk is quite stable
> but still lacks some things. E.g. blacklisting / whitelisting gateways,
> IPv6, etc.

Okay but it will 	likely be usable without crashing right?

Last but not least:
How can I configure batman advanced in /etc/config/batman-adv to enable gw 
server/client mode?

Greetings
Clemens

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Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Marek Lindner]

On Tuesday, July 06, 2010 23:46:36 Clemens John wrote:
> Okay I did this but I have some questions left:

No problem.  :)


> Does the DHCP server on the gateway need to distribute IP-Adresses?

The server should distribute IP addresses and a default route to itself. I'm 
not sure whether you will find a dhcp server which does not distribute IPs but 
default routes.


> If so I think they have to be distributet on the batman interface right?

Correct.


> Does the Batman advanced interface on the clients need to request an
> IP-Adress from the DHCP server or can I also set a static IP adress?

That depends on your needs. Any interface which is supposed to use the gateway 
feature has to run a dhcp client. If the batX interface on the client does not 
need it you can give it a static address. If you just want to define the IP 
address of a specific host you can also work with aliases / multiple IPs per 
interface.


> If the clients need to request an IP adress from the DHCP server, where is
> the difference between requesting an IP without Batman advanced and with
> Batman advanced? Does Batman advanced say from wich server to request the
> IP or which default route to choose?

Normal dhcp requests are broadcasted through the entire network. Every dhcp 
server that receives this request will answer. If the client receives multiple 
answers it depends on the implementation to choose its "favorite" dhcp server. 
Most clients simply use the first server that answered.
If you enable the gateway client this request will not be broadcasted but 
directly sent to the chosen gateway. The other dhcp servers will not receive 
this dhcp request.


> Sry for this question we just discussed this on the last community meeting
> and somebody wondered if this is the most beautiful way. Maybe it´s not
> but you are right there is no other way.

We had this layer2/layer3 discussion quite often and this is the compromise we 
managed to achieve. It only works when enabled and indirectly via dhcp. It is 
not "beautiful" but it works.  :)


> Okay but it will likely be usable without crashing right?

No, it should not crash. I'm using it on a daily basis without problems.


> How can I configure batman advanced in /etc/config/batman-adv to enable gw
> server/client mode?

Since it was not part of an official release it also is not supported by the uci 
scripts. You would have add it yourself.

Regards,
Marek

Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Clemens John]

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Thank you a lot for you answers!

I still got two question left that I remembered when I read your answers:
We discussed our networksetup on IRC (you remember?) and we decided to choose 
the setup with tinc an not sending batman advanced packages over VPN.

Now batman advanced nodes behind the VPN does not get listet in the originator 
tables of nodes on the other side of the VPN.
But do they get listed on the gateway list? Can Batman advanced choose a 
gateway behind the VPN?

I can not test this at the moment so I have to ask.

Last one: Is it right that the trunk version of batman advanced is not 
compatible with Batman advanced 0.2.1? Is trunk compatible with 2010.0.0?

Thank you
Clemens

Am Mittwoch 07 Juli 2010, 00:06:51 schrieb Marek Lindner:
> On Tuesday, July 06, 2010 23:46:36 Clemens John wrote:
> > Okay I did this but I have some questions left:
> No problem.  :)
> 
> > Does the DHCP server on the gateway need to distribute IP-Adresses?
> 
> The server should distribute IP addresses and a default route to itself.
> I'm not sure whether you will find a dhcp server which does not distribute
> IPs but default routes.
> 
> > If so I think they have to be distributet on the batman interface right?
> 
> Correct.
> 
> > Does the Batman advanced interface on the clients need to request an
> > IP-Adress from the DHCP server or can I also set a static IP adress?
> 
> That depends on your needs. Any interface which is supposed to use the
> gateway feature has to run a dhcp client. If the batX interface on the
> client does not need it you can give it a static address. If you just want
> to define the IP address of a specific host you can also work with aliases
> / multiple IPs per interface.
> 
> > If the clients need to request an IP adress from the DHCP server, where
> > is the difference between requesting an IP without Batman advanced and
> > with Batman advanced? Does Batman advanced say from wich server to
> > request the IP or which default route to choose?
> 
> Normal dhcp requests are broadcasted through the entire network. Every dhcp
> server that receives this request will answer. If the client receives
> multiple answers it depends on the implementation to choose its "favorite"
> dhcp server. Most clients simply use the first server that answered.
> If you enable the gateway client this request will not be broadcasted but
> directly sent to the chosen gateway. The other dhcp servers will not
> receive this dhcp request.
> 
> > Sry for this question we just discussed this on the last community
> > meeting and somebody wondered if this is the most beautiful way. Maybe
> > it´s not but you are right there is no other way.
> 
> We had this layer2/layer3 discussion quite often and this is the compromise
> we managed to achieve. It only works when enabled and indirectly via dhcp.
> It is not "beautiful" but it works.  :)
> 
> > Okay but it will likely be usable without crashing right?
> 
> No, it should not crash. I'm using it on a daily basis without problems.
> 
> > How can I configure batman advanced in /etc/config/batman-adv to enable
> > gw server/client mode?
> 
> Since it was not part of an official release it also is not supported by
> the uci scripts. You would have add it yourself.
> 
> Regards,
> Marek

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Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Marek Lindner]

On Wednesday, July 07, 2010 00:21:38 Clemens John wrote:
> I still got two question left that I remembered when I read your answers:
> We discussed our networksetup on IRC (you remember?) and we decided to
> choose the setup with tinc an not sending batman advanced packages over
> VPN.

Oh yeah, I remember. Did you document your setup somewhere ? Others might find 
it useful to see why & how you did it.


> Now batman advanced nodes behind the VPN does not get listet in the
> originator tables of nodes on the other side of the VPN.
> But do they get listed on the gateway list? Can Batman advanced choose a
> gateway behind the VPN?

No, because the gateway information travel with the OGMs which you don't have 
on your VPN. Sending dhcp requests via unicast also does not work because the 
VPN interfaces are not controlled by batman.


> Last one: Is it right that the trunk version of batman advanced is not
> compatible with Batman advanced 0.2.1? Is trunk compatible with 2010.0.0?

No, the trunk is not compatible with any stable version. This has a very 
simple reason: It contains features which either change the packet format or 
change the behaviour or both. For instance, the gateway feature changes the 
packet format ...

Cheers,
Marek

Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Clemens John]

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Am Mittwoch 07 Juli 2010, 00:30:30 schrieb Marek Lindner:
> On Wednesday, July 07, 2010 00:21:38 Clemens John wrote:
> > I still got two question left that I remembered when I read your answers:
> > We discussed our networksetup on IRC (you remember?) and we decided to
> > choose the setup with tinc an not sending batman advanced packages over
> > VPN.
> 
> Oh yeah, I remember. Did you document your setup somewhere ? Others might
> find it useful to see why & how you did it.

Yes we did some verry little documentation [1] but this is still the pure 
configuraion without explenations  because we are currently testing some 
different configurations for example some IPv6 stuff and a script which can 
automatically announce tinc installations with configuration and certificates on 
a central server for automatic tinc installations etc..

I hope this will get better in the next time.

[1] http://wiki.freifunk-
ol.de/index.php?title=OpenWrt_Freifunk_Standartkonfiguration

> > Now batman advanced nodes behind the VPN does not get listet in the
> > originator tables of nodes on the other side of the VPN.
> > But do they get listed on the gateway list? Can Batman advanced choose a
> > gateway behind the VPN?
> 
> No, because the gateway information travel with the OGMs which you don't
> have on your VPN. Sending dhcp requests via unicast also does not work
> because the VPN interfaces are not controlled by batman.

Mhh...
The only way to solve this would be to send whole batman advanced frames over 
Tinc VPN right (we called this solution 3 in the irc session)?

Would this be possible? I know that we than have the MTU problem again and 
higher traffic load (what would not be so fatal because we have no cetral server 
with tinc).

Our current setup makes not much sense if we use Batman advanced with gateway 
mode because we do not have a gateway in each cloud and it would be difficult to 
get one to each cloud.
The best way would be a solution that can use all gateways available in the 
network without extra configuration for each cloud.

Can you give me a short example of how to fix the mtu problem with this method? 
Offcourse we are going to document both solutions ;)

Thank you
Clemens

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Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Marek Lindner]

On Wednesday, July 07, 2010 01:45:30 Clemens John wrote:
> Yes we did some verry little documentation [1] but this is still the pure
> configuraion without explenations  because we are currently testing some
> different configurations for example some IPv6 stuff and a script which can
> automatically announce tinc installations with configuration and
> certificates on a central server for automatic tinc installations etc..
> 
> I hope this will get better in the next time.

That would be great!


> Our current setup makes not much sense if we use Batman advanced with
> gateway mode because we do not have a gateway in each cloud and it would
> be difficult to get one to each cloud.
> The best way would be a solution that can use all gateways available in the
> network without extra configuration for each cloud.

This sounds overly complicated. I don't fully understand your setup & 
requirements yet which is also one reason for asking for documentation. 
What your are trying to solve is this (I'm guessing here):

wifi client <> batman node <> VPN <> batman node <> batman with internet

And you have several of these "batman with internet" but not in each cloud and 
want each client to choose its best ?

Regards,
Marek

Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Clemens John]

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Am Mittwoch 07 Juli 2010, 13:16:11 schrieb Marek Lindner:
> > Our current setup makes not much sense if we use Batman advanced with
> > gateway mode because we do not have a gateway in each cloud and it would
> > be difficult to get one to each cloud.
> > The best way would be a solution that can use all gateways available in
> > the network without extra configuration for each cloud.
> 
> This sounds overly complicated. I don't fully understand your setup &
> requirements yet which is also one reason for asking for documentation.
> What your are trying to solve is this (I'm guessing here):
> 
> wifi client <> batman node <> VPN <> batman node <> batman with internet
> 
> And you have several of these "batman with internet" but not in each cloud
> and want each client to choose its best ?

Right and the wifi clients have no batman advanced installed. Currently they 
are getting their IP and defaultroute from a central dhcp server.

Thank you
Clemens

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Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Marek Lindner]

On Wednesday, July 07, 2010 13:25:51 Clemens John wrote:
> Right and the wifi clients have no batman advanced installed. Currently
> they are getting their IP and defaultroute from a central dhcp server

Wow - when it comes to your setup and requirements you know how to keep your 
answer short. I hoped you would say a bit more ... :)

At this point I don't see why you would need to use the gateway feature at 
all. There is nothing to optimize.

Regards,
Marek

Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Clemens John]

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Am Mittwoch 07 Juli 2010, 14:10:33 schrieb Marek Lindner:
> On Wednesday, July 07, 2010 13:25:51 Clemens John wrote:
> > Right and the wifi clients have no batman advanced installed. Currently
> > they are getting their IP and defaultroute from a central dhcp server
> 
> Wow - when it comes to your setup and requirements you know how to keep
> your answer short. I hoped you would say a bit more ... :)
> 
> At this point I don't see why you would need to use the gateway feature at
> all. There is nothing to optimize.

Yes the network is working well but in this setup the central dhcp server is 
the only gateway because I only get the defaultroute of this server.

What if I have more gateways? I know that I can set the defaultroute to this 
server by hand but a "normal" user can´t do this. I need a method to choose 
the gateway individually and automatically so that the user gets the best 
gateway available.

Are there any ideas to do this? Or am I completely on the wrong way?

Thank you
Clemens

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Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Antonio Quartulli]

On Wed, Jul 07, 2010 at 02:33:53PM +0200, Clemens John wrote:
> Am Mittwoch 07 Juli 2010, 14:10:33 schrieb Marek Lindner:
> > On Wednesday, July 07, 2010 13:25:51 Clemens John wrote:
> > > Right and the wifi clients have no batman advanced installed. Currently
> > > they are getting their IP and defaultroute from a central dhcp server
> > 
> > Wow - when it comes to your setup and requirements you know how to keep
> > your answer short. I hoped you would say a bit more ... :)
> > 
> > At this point I don't see why you would need to use the gateway feature at
> > all. There is nothing to optimize.
> 
> Yes the network is working well but in this setup the central dhcp server is 
> the only gateway because I only get the defaultroute of this server.
> 
> What if I have more gateways? I know that I can set the defaultroute to this 
> server by hand but a "normal" user can´t do this. I need a method to choose 
> the gateway individually and automatically so that the user gets the best 
> gateway available.
> 
> Are there any ideas to do this? Or am I completely on the wrong way?
> 

If I'm not wrong, at this point you could put a dhcp server on each
gateway and use the gw-mode feature of batman, so that each gw will
anounce itself as gw and a dhcp request, becoming from a client, will be
redirected to the best gw in the mesh.


Please someone corrects me if I am wrong.

> Thank you
> Clemens

Regards


-- 
Antonio Quartulli

..each of us alone is worth nothing..
Ernesto "Che" Guevara

Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Clemens John]

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Am Mittwoch 07 Juli 2010, 14:44:17 schrieb Antonio Quartulli:
> > Yes the network is working well but in this setup the central dhcp server
> > is the only gateway because I only get the defaultroute of this server.
> > 
> > What if I have more gateways? I know that I can set the defaultroute to
> > this server by hand but a "normal" user can´t do this. I need a method
> > to choose the gateway individually and automatically so that the user
> > gets the best gateway available.
> > 
> > Are there any ideas to do this? Or am I completely on the wrong way?

Marek asked me to describe our setup a bit more particularly so I´ll try to:

We have several clouds that can not see each other via WLAN.
These clouds are connected to each other with Tinc VPN via the Internet.
Batman runs only on WLAN, not on the VPN.
The clients usually have no Batman advanced but connecting via a wlan 
interface which is bridged with bat0.
The Tinc VPN interface is bridged with bat0 too.

All Nodes which are not a gateway have a link local IPv6 address only.
We have a node with a DHCP server which is also gateway.
This node has an IPv4 address and distributes IPv4 addresses with DHCP.
Clients now get an IPv4 address from this node and set their default route to 
this node to get Internet. 

The exact setup (only configurationfiles) is listed here:
http://wiki.freifunk-ol.de/index.php?title=OpenWrt_Freifunk_B.A.T.M.A.N-
advanced_konfiguration_2

With Tinc we are now well decentralised but we currently have the centralised 
gateway solution left so we would also like to decentralize the Gateway thing.
That means multiple gateways with DHCP servers in different clouds (but not in 
every cloud).
Each client should in theory have access to any gateway, but in practice they 
always get automatically access to the internet via the best possible gateway.

The question why the traffic is in some cases first routet through the VPN and 
then headed to the Internet is pretty easy to answer:
We have 3 clouds. In two of them are people who are confident (the whole is 
indeed always a matter of law) with offering a gateway. The third cloud now in 
theory is connected to the Internet.
But the person who offers the connection to the VPN does not want to head the 
traffic of the network through his connection direcly to the internet (because 
of reasons of law) so clients in this cloud have to use a gateway on the other 
side of the VPN.

> If I'm not wrong, at this point you could put a dhcp server on each
> gateway and use the gw-mode feature of batman, so that each gw will
> anounce itself as gw and a dhcp request, becoming from a client, will be
> redirected to the best gw in the mesh.
> 
> Please someone corrects me if I am wrong.

This sounds interesting. Is this practicalbe? Has somebody tried this already 
or does someone know a better solution?

Btw.: Big thank you for so much patience ;)
I´m also online on irc so maybe we can discuss these questions there?

Greetings
Clemens

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Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Clemens John]

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Am Mittwoch 07 Juli 2010, 00:30:30 schrieb Marek Lindner:
> > Now batman advanced nodes behind the VPN does not get listet in the
> > originator tables of nodes on the other side of the VPN.
> > But do they get listed on the gateway list? Can Batman advanced choose a
> > gateway behind the VPN?
> 
> No, because the gateway information travel with the OGMs which you don't
> have on your VPN. Sending dhcp requests via unicast also does not work
> because the VPN interfaces are not controlled by batman.

I just had another Idea but I´m not shure if this will work.

If we don´t use the Batman advanced gateway feature but run a DHCP Server on 
gateways only, would a client always choose the "nearest" DHCP server?

So if I´m connected wireless to a router that is a gateway and runs a dhcp 
server would my laptop always choose this router as defaultroute also if there 
are other routers in the network with a dhcp server running?

If this works I can not choose the "best" gateway, but I would always have the 
nearest gateway.

If this works, is it possible that all dhcp servers distribute the same ip 
range? Will a client/server notice which IP´s are already assigned to clients?

Thank you
Clemens

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Re: [B.A.T.M.A.N.] Batman advanced and internet gateways

[Andrew Lunn]

On Wed, Jul 07, 2010 at 12:33:47PM +0200, Clemens John wrote:
> Am Mittwoch 07 Juli 2010, 00:30:30 schrieb Marek Lindner:
> > > Now batman advanced nodes behind the VPN does not get listet in the
> > > originator tables of nodes on the other side of the VPN.
> > > But do they get listed on the gateway list? Can Batman advanced choose a
> > > gateway behind the VPN?
> > 
> > No, because the gateway information travel with the OGMs which you don't
> > have on your VPN. Sending dhcp requests via unicast also does not work
> > because the VPN interfaces are not controlled by batman.
> 
> I just had another Idea but I?m not shure if this will work.
> 
> If we don?t use the Batman advanced gateway feature but run a DHCP Server on 
> gateways only, would a client always choose the "nearest" DHCP server?

It will likely choose the first to reply. You cannot guarantee the
first to reply is the nearest, it depends on what else they are is
doing at the same time, e.g. the nearest could be busy moving packets
between networks so has higher latency than an idle device a bit
further away.
 
> If this works, is it possible that all dhcp servers distribute the same ip 
> range? Will a client/server notice which IP?s are already assigned to clients?

Not recommended. Often the server will test to see if the address is
in use by ping'ing it, but this is not always implemented and is not a
guaranteed to work in all conditions. It is much better to allocate to
each server a unique range of addresses. These can however be inside
the same subnet.

    Andrew