On 07/04/17 11:22, Nikksno via lime-users wrote:

Thank you Nicolas,

What I mean is that if I do the setup ad you said, so ISP ROUTER Lan [eth] First LiMe router Wan and then First LiMe router Lan [eth] other LiMe router's LAN ports, if I connect a wired client [say a desktop pc] to that huge Lan, it will receive several DHCP broadcasts. This might not be an issue as you're saying since they all advertise the same stuff, but I don't understand how all LiMe nodes can apparently respond to 10.13.0.1 on that **wired** network. I know about the trick on the wireless / Lan side of every node, and I've always found it a genius trick, I just don't understand how it can work to connect several LANs together over wired, especially since they all try to have the same IP.

As you probably already know, all lime nodes have the same MAC (anyMAC) and the same IP (anyIP), we call this "any gateway" or anyGW.

What happens if two nodes and a client are wired connected to the same LAN and a client sends a packet to the network gateway?

If two nodes are connected through an Ethernet switch, as both of them have the same MAC the switch will decide to which port each packes is sent. Usually the nearest is the one with more possibilities for receive the packet, however it might change in some moment. Anyway it won't be a problem, batman-adv takes care of the layer two (for the WiFi mesh) and it's bridged to the wired br-lan network, so the packet will arrive to its destination and also the reply will arrive to the client, it does not matter via which libremesh node (the first one which drops the packet to the layer2 network).

There are only two scenarios where this behavior (switch changes the port for the anyMAC address) will be a problem:

1) TCP connections from the client to the node connected to the switch (session will be lost, but this cases are not very common and you can always use the uniq IP to reach a libremesh gateway).

2) If the two libremesh nodes connected to the same switch are using different mesh gateways to the Internet the TCP connections will be lost. However this is a strange case cause bmx6 decides the gw following the same heuristics and both nodes are very close.

Hope it is clear enough, you might find some more information on the comments of this discussion:

https://github.com/libremesh/lime-packages/issues/108

In any event, this setup has an issue whereby DHCP advertisements [if that's what they're called] of LiMe nodes connected lan-to-lan travel upwards through the wan port of the first lime node [the one connected to the ISP router via its wan port, as you suggested] and confuses the ISP router itself, to such point that my ISP router wasn't managing to connect upstream to the VDSL endpoint, and was not connecting to the public facing internet. As soon as I disconnected the cable going from the ISP router's LAN port to the first lime node's wan port, the ISP router started working again.

Sorry but I don't understand this behavior :/

Also, as soon as we figure this stuff out, and I understand it [hardest part ;], I volunteer to write a fully detailed guide on how to design a lime topology so that our design works all across the world, and deployers like me know how to engineer their networks.

that would be great :)

Thanks again to both of you

Nk

From: Nicolas Pace <nico@libre.ws>
Sent: Jul 3, 2017 10:20 AM
To: Nk; libremesh users
Subject: Re: [lime-users] DHCP conflicts

On July 2, 2017 8:31:44 PM GMT+03:00, Nk via lime-users wrote: > Thank you Nicolas, so what you're saying is that instead of > connecting > the ISP router to the switch, and then having cables from the switch > going either to the wan port of LiMe routers [if they have one] or to > their Lan port [if it's the only one they have], I should connect the > ISP router directly to the wan port of a LiMe router that has both, > such as a 1043 or a C7, and then connecting all other nodes to that > device's Lan ports, or, should they not suffice, draw a cable from > that > router's LAN port to the switch, and then connect all other devices > to > the switch, is this correct? So, from my point of view, best possible scenario is for all libremesh routers to be connected via cable through the LAN sockets. If they are too far to reach via a cable (+100m) i would use Wifi. > This way, you say, only the first LiMe router receives the external > DHCP. But still there are multiple advertisements. Not in the same network. You have one DHCP in the outside network between the ISP Gateway and the first LibreMesh router, and you have a cloud of LibreMesh DHCP routers in the other network. > Is this not a > problem any more since they are all the same, is this your point? Yes > > But still, how can all LiMe routers on that wired network have > the 10.13.0.1 IP at that point though? That is a 'trick' of the LibreMesh Routers... they announce the same Gateway IP, that is a local IP of each router, to allow Roaming devices between Access Points.
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