Does batman choose DHCP server by random?

Does batman choose DHCP server by random?

[MK]

Hi meshing list.

We are running a batman 2020.2 based mesh network.

Clients connect to one gateway but pull IPv4 addresses from _another_
gateway. This leads to packets flowing between gateways instead of
leaving the mesh on the shortest route possible.

Is this intended behaviour? Is it random? Is there a config option to
alter this packet flow?

gw_mode is set to "server" on all gateways, bandwith announcement is the
same on all gateways (10/10 MBit). So no imbalance here.

Regards,
Martin

Re: Does batman choose DHCP server by random?

[Sven Eckelmann]

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On Thursday, 17 September 2020 22:23:24 CEST MK wrote:
> Clients connect to one gateway but pull IPv4 addresses from _another_
> gateway. This leads to packets flowing between gateways instead of
> leaving the mesh on the shortest route possible.
> 
> Is this intended behaviour? Is it random? Is there a config option to
> alter this packet flow?

See https://www.open-mesh.org/projects/batman-adv/wiki/Gateways

Kind regards,
	Sven

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Re: Does batman choose DHCP server by random?

[MK]

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Hi Sven.

> See https://www.open-mesh.org/projects/batman-adv/wiki/Gateways

We did set up all batctl values according to the manual, but still get
IPs/Leases from other gateway's ranges and therefore cross-traffic...

Any hint on what we did wrong?

Server:
$ batctl gwl
[B.A.T.M.A.N. adv 2020.2, MainIF/MAC: fastd_mesh/ (bat0/ BATMAN_V)]
  Router            ( throughput) Next Hop          [outgoingIf]  Bandwidth
   (        7.7)  [fastd_mesh]: 10.0/10.0 MBit
   (        7.7)  [fastd_mesh]: 10.0/10.0 MBit
   (       10.0)  [fastd_mesh]: 10.0/10.0 MBit
   (        8.8)  [fastd_mesh]: 10.0/10.0 MBit
   (        7.7)  [fastd_mesh]: 10.0/10.0 MBit
   (        8.8)  [fastd_mesh]: 10.0/10.0 MBit

$ batctl gw_mode
server (announced bw: 10.0/10.0 MBit)

$ batctl -v
batctl 2020.2 [batman-adv: 2020.2]

Client:
https://github.com/ffulm/firmware/blob/ec1d061e20557662dd8c7fc75dc603fee9bf77e0/files/etc/uci-defaults/50_freifunk-setup#L207

Regards,
 Martin



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Re: Does batman choose DHCP server by random?

[Marek Lindner]

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On Tuesday, 29 September 2020 22:04:58 CEST MK wrote:
> > See https://www.open-mesh.org/projects/batman-adv/wiki/Gateways
> 
> We did set up all batctl values according to the manual, but still get
> IPs/Leases from other gateway's ranges and therefore cross-traffic...

Have you also taken care of the gateway client settings ? If so, feel free to 
share your config.

Kind regards,
Marek Lindner




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Re: Does batman choose DHCP server by random?

[Sven Eckelmann]

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On Tuesday, 29 September 2020 22:04:58 CEST MK wrote:
[...]
> Client:
> https://github.com/ffulm/firmware/blob/ec1d061e20557662dd8c7fc75dc603fee9bf77e0/files/etc/uci-defaults/50_freifunk-setup#L207

I think you forgot to paste the information here. It is not really relevant 
what the server sees when the gw client has to decide where the IPv4 DHCP 
Broadcast packet has to go.

Kind regards,
	Sven

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Re: Does batman choose DHCP server by random?

[MK]

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Hi Sven & Marek!

Thanks for your help. Find the client side config down below:

$ batctl -v
batctl openwrt-2019.2-3 [batman-adv: openwrt-2019.2-4]

$ batctl gwl
[B.A.T.M.A.N. adv openwrt-2019.2-4, MainIF/MAC: fastd_mesh/ (bat0/
BATMAN_V)]
  Router            ( throughput) Next Hop          [outgoingIf]  Bandwidth
   (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
   (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
   (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
   (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
   (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
*  (        1.0)  [fastd_mesh]: 10.0/10.0 MBit

 Star means choosen gateway?

$ batctl gw_mode
client (selection class: 5.0 MBit)


Regards,
Martin


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Re: Does batman choose DHCP server by random?

[Sven Eckelmann]

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On Friday, 2 October 2020 10:29:16 CEST MK wrote:
[...]
> $ batctl gwl
> [B.A.T.M.A.N. adv openwrt-2019.2-4, MainIF/MAC: fastd_mesh/ (bat0/
> BATMAN_V)]
>   Router            ( throughput) Next Hop          [outgoingIf]  Bandwidth
>    (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>    (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>    (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>    (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>    (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
> *  (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
> 
>  Star means choosen gateway?

Yes, this is the chosen gateway. And the "1.0" here means most likely that the 
throughput to this gateway is for some reason always the same - so it has no 
good way to figure out the best gateway.

Please make sure that you either only use links that provide an expected 
throughput for its peers - OR use the throughput_override [1] on interfaces
which cannot provide an automated expected throughput for its peers. Also
make sure that you don't forget this setting on one side of the connection.


And can you please explain how you were able to get this output without the 
router mac address? Because this is a bug and I cannot reproduce it at the 
moment.

Kind regards,
	Sven

[1] https://www.open-mesh.org/projects/batman-adv/wiki/Tweaking#throughput_override

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Re: Does batman choose DHCP server by random?

[MK]

Hi Sven.

Thanks for the hints!
I deleted MACs manually. So this is not a bug ;)

Regards
Martin

02.10.2020 11:25:43 Sven Eckelmann <sven@narfation.org>:

> On Friday, 2 October 2020 10:29:16 CEST MK wrote:
> [...]
>> $ batctl gwl
>> [B.A.T.M.A.N. adv openwrt-2019.2-4, MainIF/MAC: fastd_mesh/ (bat0/
>> BATMAN_V)]
>> Router            ( throughput) Next Hop          [outgoingIf]  Bandwidth
>> (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>> (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>> (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>> (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>> (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>> *  (        1.0)  [fastd_mesh]: 10.0/10.0 MBit
>> 
>> Star means choosen gateway?
> 
> Yes, this is the chosen gateway. And the "1.0" here means most likely that the
> throughput to this gateway is for some reason always the same - so it has no
> good way to figure out the best gateway.
> 
> Please make sure that you either only use links that provide an expected
> throughput for its peers - OR use the throughput_override [1] on interfaces
> which cannot provide an automated expected throughput for its peers. Also
> make sure that you don't forget this setting on one side of the connection.
> 
> And can you please explain how you were able to get this output without the
> router mac address? Because this is a bug and I cannot reproduce it at the
> moment.
> 
> Kind regards,
> Sven
> 
> [1] https://www.open-mesh.org/projects/batman-adv/wiki/Tweaking#throughput_override
>