On 14/05/18 18:50, Chris Green wrote: > I have a large house and run two Draytek Vigor routers to provide full > coverage. The 'main' router is a Draytek 2860n which has the VDSL > connection to the internet. The second router is a Draytek Vigoer > 2820n which has no WAN connections and just has its LAN connected to > the 2860n's LAN side. > > DHCP/DNS is provided by a Raspberry Pi running dnsmasq. Everything is > otherwise pretty standard, 192.168.1.x private network with the 2860n > at 192.168.1.1 and the Pi at 192.168.1.2. > > I have the routers' WiFi set up so they have different SSIDs. In > general it all works fine, I can connect my laptop to either SSID as > required. > > The problem I have is when I move around the house. My laptop runs > xubuntu 17.10 and uses Network Manager to handle the networking. So, > say I'm connected to 2820n and move to the other side of the house > where I need to connect to 2860n. I manually use the Network Manager > applet to disconnect from 2820n and connect to 2860n. It appears to > work fine and says I'm connected but most times that I do this the > DHCP set-up fails. I have a connection but there is no default route > and no DNS and the laptop has no IP address assigned (all IPV4 this). > Sometimes it works OK and usually if I disconnect and wait a while > (say a minute or two) and then reconnect it will work OK. > > It seems as if dhclient is failing as if I run it manually when in the > not working state it just hangs. Does dnsmasq have some sort of delay > before 'dropping' a DHCP client? I.e. is it possible that dnsmasq > sees the same MAC address re-connecting and assumes that it still has > its IP setup? If so is there some way I can make dnsmasq quicker at > seeing that a client has disconnected? >
This looks more like a layer-2 problem than a DHCP/IP one. There's one IP network, so the host should just be able to continue with the existing DHCP lease. To work, though, it does require that the layer-2 ethernet switches note that the topology of the network has changed, and that the packets to the MAC address in question have to go over different network ports. I suspect that the couple of minutes delay is timeout on that, but I don't have any concrete suggestions on how to fix it. I think the SSID change is a red-herring. cheers, Simon _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss