Two Cable Modems w/ Same IP
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@gabacho4 Arris SB8200 and Motorola MB8611.
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@ptyork Your best bet here is to google search the model number and "enable bridge mode" to see how to do it.
Ryan
Repeat, after me: MESH IS THE DEVIL! MESH IS THE DEVIL!
Requesting firmware for your Netgate device? https://go.netgate.com
Switching: Mikrotik, Netgear, Extreme
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@andyrh cable modems are a bit odd. The ISP assigns you an IP address from their own DHCP range. And at least on these, the admin IP is fixed. Printed on a sticker on the bottom. There truly are almost no configuration options on these. You're not even allowed to update your own firmware. Only the ISP can do that...yes...even for a modem that you own. DOCSIS is a weird world.
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@ptyork said in Two Cable Modems w/ Same IP:
The ISP assigns you an IP address from their own DHCP range.
Yes but the modem management IP (the RFC1918 one) is not assigned out of an ISP DHCP pool
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@rcoleman-netgate ah, I think these ARE in bridge mode (vs. router mode). I was thinking you were referring to something to configure with pfSense needing to bridge two WAN ports or something.
Okay, then, yes. It sounds like I have the configuration pretty much as you describe. I just have to use the 'inelegant' solution of manually switching which of my WAN ports gets packets addressed to 192.168.100.1. Bummer, but far from the end of the world.
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@ptyork Then you need to do specific policy-based-routing to talk to a system. You can't talk to both at the same time from the same machine, basically. You put a rule on your LAN (or the interface your computer is on) that routes 192.168.100.1 out a specific gateway.
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@rcoleman-netgate thanks for the help. I think I understand. I can either toggle the static route between interfaces as I have it now or do as you suggest and set up PBR such that I can hit a different modem depending on which computer I access it from. Neither is a great solution, but either can work. Would be cool if there were some kind of NAT policy that could handle this, but I know it's a very fringe case and not worth really spending any development effort on.
Thanks to everyone for your help!!
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@ptyork said in Two Cable Modems w/ Same IP:
Would be cool if there were some kind of NAT policy that could handle this
Basically that's what the PBR is.
You could have one work from a wireless VLAN and one from a wired VLAN -- that's the suggestion I made to the last person that asked about it. -
@rcoleman-netgate understood. I just meant a way of translating and forwarding one IP address (e.g., 192.168.1.2) to another on a specific port (e.g., 192.168.100.1 on WAN2). So not a source-based policy, but one that could work from any LAN source.
Like I said, sounds like this is an edge case. Existing solutions can also work. Thanks again!
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You can try to use NAT like 192.168.101.1 to WAN2 and translate it do destination 192.168.100.1.
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Well, it's now a COMPLETELY moot point. Xfinity wanted to charge ME to add my own modem in place of their "XFi" modem/router/wifi/slicer/carrot peeler. Was going to pay more and lose unlimited data, which is exactly opposite of what I was promised when I signed up and before I dropped >$150 on a new modem. Good grief. Such an awful company...
So now I have a spare cable modem if anyone's interested. :D
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@nocling thanks! I did look at that, but I got a bit lost in all of the options. I may still play around with it to satisfy my curiosity even if I'm no longer dealing with the immediate need.
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@rcoleman-netgate said in Two Cable Modems w/ Same IP:
@ptyork Your best bet here is to google search the model number and "enable bridge mode" to see how to do it.
Those models are bridge only devices. No built in router of any kind.
Truthfully- The MB8600 with its multiple interfaces (3 under the sticker) can bond two interfaces and is capable of 2gbps.. keep that in mind as you make your decisions. (actually I think the SB8200 has two bondable ports itself..) Having two modems is not going to help you with uptime. (unless you are worrying about one dying..)
edit- and now read your last post above.. Yep Comcrap sucks like that.
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@chpalmer thanks, yep. Both are "dumb" modems; the only purpose of the admin interface is for diagnostics. Funny, although the SB8200 is capable of bonding with updated firmware, the ISP refuses to apply it. So, I'm stuck with two separate GigE ports. Not a big deal since that service is only 600/50, but it highlights the asinine nature of DOCSIS.
I do actually have two separate ISPs (WOW and "Comcrap"). I live stream some classes and just wanted to make sure I had redundancy so I don't leave my students high-and-dry. But I've had nothing but trouble ever since adding the Xfinity service. Got the MB8611 for its 2.5GbE port since I had > 1Gbps with Comcast, but c'est la vie.
