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We have two ISPs at home, and I've connected a different router to each and both routers into our LAN, one large ethernet switch that everything connects to. One router has the IP 192.168.1.1
and connects through Time Warner Cable, and the other has 10.0.1.1
and connects through Verizon. Both are DHCP servers as well.
For whatever reason, anything with DHCP enabled seems to take a DHCP lease from 192.168.1.1
, thus accepting 192.168.1.1
as the router and connecting to the Internet through TWC. I don't know if that's because that router just always "wins" a race condition or if there's some actual priority. How do computers choose which router to take the DHCP lease from?
I don't have enterprise-level hardware. The router on TWC is an Apple AirPort Extreme, and the one on Verizon is the Actiontec they gave us. AFAIK I can't set up either to host one DHCP server for both routers. I've got a Mac server that can serve DHCP, but I can't rely on it. And when I Google for solutions involving multiple routers, I get people who think that router = wireless access point.
1Keep in mind that a router will probably distribute DHCP addresses even when its internet is down. (It may come back any second!) You may want a multi-WAN Router that is transparent to all the devices behind it. – DasKrümelmonster – 2016-07-16T22:12:26.243
What is the Actiontec connected to? Ethernet? DSL line? Cable? Fiber? (I'm guessing the AirPort is connected via Ethernet to the cable modem?) – user1686 – 2016-07-16T22:12:34.033
just read your title not your whole post.. I think your computer has a default gateway specified.. Gateway=router. And it might show in your computer's routing table (your computer has a routing table, and has the potential to be a whole router, but by default doesn't take traffic on input and forward it on, so is not a router.. but still has a routing table). And the routing table decides where to route traffic that originates on that computer. – barlop – 2016-07-16T22:15:31.323
@grawity The Actiontec is connected to the Verizon modem via ethernet. AirPort is connected to the TWC modem via ethernet. – sudo – 2016-07-16T22:23:17.860
@barlop Unless I'm misunderstanding, the routing table seems to be set after the computer chooses a DHCP server (however it does that). – sudo – 2016-07-16T22:24:44.680
1@sudo: Ok, so if you got a multi-WAN router, you'd connect it via ethernet to both modems directly, without using the current ones. – user1686 – 2016-07-16T22:26:06.013
Hmm. I guess that would be ideal then. – sudo – 2016-07-16T22:31:27.307
1It does not make sense to have two DHCP servers on the same LAN. Yes, there is a race condition. Does it really make sense to have two ISPs on the same LAN at all? Once they are behind a switch, you kind of lose any benefit of having them both, unless your switch has special rules for routing specific traffic to one ISP or the other. In which case, the switch should be repkaced with a 3rd router that acts as the DHCP server for the LAN. ISPs are separate networks, a router is used to join multiple networks together. Switches are for joining segments of the same network together. – Remy Lebeau – 2016-07-16T22:33:09.920