Any suggestions about configuring batman-adv gateways + modems

Any suggestions about configuring batman-adv gateways + modems

[Xuebing Wang]

Hi batman-adv community,

We have been building openwrt 15.05 + batman-adv mesh network for over 2 
years, they work great.

We are planning to use batman-adv gateways + 4G modems. For an example: 
our mesh network is with 20 nodes, 3 nodes have 4G modems connected.

1) My first thought is to use batman-adv gateway (with 4G modem 
connected) as dhcp server, and forward batman-adv interface to wan 
interface (modem).
1.1)  But, there is an issue with this setup. Once a modem is down, 
nodes that are connected to this batman-adv gateway (with modem) can not 
automatically "roam" to another batman-adv gateway (with good modem 
connection).
1.2)  This behavior is expected, right?

2) My second thought is to bridge batman-adv interface and wan interface 
(modem). This works great, I do not see issue (1.1) above.
-  By this setup, all batman-adv clients get ip via dhcp and via modem.
2.1)  Is this the suggested setup to use batman-adv gateways?

3) When I bridge batman-adv interface with other interface (as in step 2 
above), can I use batman-adv interface via *ipv6* to ping other 
batman-adv nodes?

Thanks.
Xuebing Wang

Re: Any suggestions about configuring batman-adv gateways + modems

[Marek Lindner]

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Hi,

On Friday, 8 November 2019 18:51:14 HKT Xuebing Wang wrote:
> We have been building openwrt 15.05 + batman-adv mesh network for over 2
> years, they work great.

hopefully, the batman-adv version you are using is newer than 15.05 ...


> 1) My first thought is to use batman-adv gateway (with 4G modem
> connected) as dhcp server, and forward batman-adv interface to wan
> interface (modem).
>
> 1.1)  But, there is an issue with this setup. Once a modem is down,
> nodes that are connected to this batman-adv gateway (with modem) can not
> automatically "roam" to another batman-adv gateway (with good modem
> connection).

Why not ? What should prevent nodes or clients to choose another batman-adv 
gateway ?


> 2) My second thought is to bridge batman-adv interface and wan interface
> (modem). This works great, I do not see issue (1.1) above.

Can you elaborate ? Are you comparing bridging vs routing ? What's the main 
difference between 1.1 and 2. which makes you think it works better ?


> 3) When I bridge batman-adv interface with other interface (as in step 2
> above), can I use batman-adv interface via *ipv6* to ping other
> batman-adv nodes?

You can always ping or transfer any IPv4/IPv6 payload over batman-adv 
regardless of your WAN setup. In fact, you could operate batman-adv without 
any WAN uplink at all.

Cheers,
Marek

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Re: Any suggestions about configuring batman-adv gateways + modems

[Marek Lindner]

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Hi,

> Thank you for your help, as I did not subscribe to the mailing list, I did
> not get your reply. I subscribe to the mailing list now and I am writing a
> new email thread.

apologies, was not aware of that.


> When modem at gateway (for WAN uplink) is down and loses internet
> connection (but batman-adv connections with clients are good and dhcp
> server works good), can batman-adv clients know that internet connection is
> lost and "roam" to another gateway with good internet connection?

Seems you are looking for this:
https://www.open-mesh.org/projects/batman-adv/wiki/Gateways

Kind regards,
Marek

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Any suggestions about configuring batman-adv gateways + modems

[Xuebing Wang]

Hi Marek,

Thank you for your help, as I did not subscribe to the mailing list, I 
did not get your reply. I subscribe to the mailing list now and I am 
writing a new email thread.


 >> We have been building openwrt 15.05 + batman-adv mesh network for over 2
 >> years, they work great.
 >
 >hopefully, the batman-adv version you are using is newer than 15.05 ...
 >
 >
 >> 1) My first thought is to use batman-adv gateway (with 4G modem
 >> connected) as dhcp server, and forward batman-adv interface to wan
 >> interface (modem).
 >>
 >> 1.1)  But, there is an issue with this setup. Once a modem is down,
 >> nodes that are connected to this batman-adv gateway (with modem) can not
 >> automatically "roam" to another batman-adv gateway (with good modem
 >> connection).
 >
 >Why not ? What should prevent nodes or clients to choose another 
batman-adv
 >gateway ?

When modem (for WAN uplink) at gateway is down and loses internet 
connection (but batman-adv connections with clients are good and dhcp 
server works good), can batman-adv clients know that internet connection 
at gateway is lost and "roam" to another gateway with good internet 
connection?

Thanks.
Xuebing Wang

Any suggestions about configuring batman-adv gateways + modems

[Xuebing Wang]

Hi Marek,

Thank you very much for your help.

 >> When modem at gateway (for WAN uplink) is down and loses internet
 >> connection (but batman-adv connections with clients are good and dhcp
 >> server works good), can batman-adv clients know that internet 
connection is
 >> lost and "roam" to another gateway with good internet connection?
 >
 >Seems you are looking for this:
 >https://www.open-mesh.org/projects/batman-adv/wiki/Gateways

Yes, batman-adv gateway is what I am using.

Do I need to write or find a daemon at gateway to sense internet 
connection, once internet connection is lost (and does not recover 
within like 2-5 minutes) then advertise batman-adv mesh network by 
"batctl gw_mode client" to turn this node to be a client?

Thanks.
Xuebing Wang

Re: Any suggestions about configuring batman-adv gateways + modems

[Marek Lindner]

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Hi,

> Yes, batman-adv gateway is what I am using.
> 
> Do I need to write or find a daemon at gateway to sense internet
> connection, once internet connection is lost (and does not recover
> within like 2-5 minutes) then advertise batman-adv mesh network by
> "batctl gw_mode client" to turn this node to be a client?

you can have a mechanism to detect if the uplink connectivity is down and then 
have the batman-adv gateway switch to client. When the uplink is back, you can 
switch to gateway mode again.

Depending on how your uplink works, you may not need to write a separate 
daemon to check (though you can if you want). Most uplink solutions provide 
some kind of scriptable event for up/down changes. Depends very much on your 
setup and what you'd like to react to. 

Cheers,
Marek

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