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[Discuss] Changing Comcast Modem to Bridged
- Subject: [Discuss] Changing Comcast Modem to Bridged
- From: jbk at kjkelra.com (jbk)
- Date: Sun, 30 Dec 2018 13:12:56 -0500
- In-reply-to: <20181230165544.C04CD142B65@localhost>
- References: <6896ae06-58a9-ebca-121a-72fb8ad0ec29@kjkelra.com> <20181230160103.87FC5142B6A@localhost> <eb08e42d-c2f9-4749-0162-82e30e249197@kjkelra.com> <20181230165544.C04CD142B65@localhost>
On 12/30/18 11:55 AM, Robert Krawitz wrote: > On Sun, 30 Dec 2018 11:39:24 -0500, jbk wrote: >> On 12/30/18 11:01 AM, Robert Krawitz wrote: >>> On Sun, 30 Dec 2018 10:39:06 -0500, jbk wrote: >>>> A couple years ago we changed to comcast as our ISP and incorporated their modem into our network topology providing the dhcp, NAT and wireless functions. >>>> >>>> Prior to this we had a DSL modem and WRT54G running tomato. The modem provided dhcp so it was the gateway address. >>>> >>>> I now want to put the Comcast modem in bridge mode and have my wireless router running dd-wrt provide the dhcp and NAT for the wireless and wired LAN. >>> I've done that by the simple expedient of connecting our domestic >>> router to our (RCN -- it doesn't matter) router, and having everything >>> else except for my server system connect to our domestic router. In >>> other words, a DMZ topology. The only thing I had to configure on the >>> RCN router was the port forwarding to any ports I want open on the >>> server. >>> >>> If you don't have a static IP/no open ports, it's even easier; the >>> only two things on the DMZ are the ISP router and the domestic >>> router. >> The problem with doing that is there is no way to turn off the >> Comcast dhcp server w/o putting it into bridged mode, other than >> limiting the range to a single address and have that lease set to >> forever. But forever on the modem is only as long as that device >> remains connected without interruption. If there is an interruption, >> power outage, then the first device detected on resumption will get >> that address lease. > You don't need to turn off the DHCP server on the Comcast router, > because you're only going to have one device attached to it, your > domestic router. Everything else connects to your domestic router, > which you configure as you please; you connect the domestic router's > uplink to the Comcast router and let the Comcast router assign the > domestic router whatever address it pleases. > >> Thanks Robert, I would have to do a lot more research to see what >> setting up a DMZ would mean to my topology and the dhcp issue is the >> biggest headache and bridge mode is the only way to turn it off on >> the modem. > Here's the configuration I'm suggesting. The "=====" network is the > DMZ, but it's simply an ethernet connection: > > +---- Internal device 1 > | > INTERNET ----- Comcast ===== Domestic --+---- Internal device 2 > | > +---- Internal device ... > > >From the standpoint of the Comcast router, it sees that it's connected > to the Internet and to one device internally (you can even turn off > the wireless altogether on it). From the standpoint of the domestic > router, it sees the Comcast router as the internet, and all of your > other devices connected to it. > > Mine's a little different because of my server, which is connected to > both the DMZ and the internal domestic network but doesn't route: > > +---- Internal deviceS > | > INTERNET -----ISP/dhcp1 ====== Router+dhcp2/WAP/VAP > | > +-----internal > Server Currently all of my devises point to ISP/dhcp1's IP as the gateway. Would I now want to have these devices point to the modem assigned dhcp address of Router/dhcp2 or the LAN address I assign to dhcp2. This is where my confusion is. -- Jim Kelly-Rand jbk at kjkelra.com
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- [Discuss] Changing Comcast Modem to Bridged
- From: jbk at kjkelra.com (jbk)
- [Discuss] Changing Comcast Modem to Bridged
- From: jbk at kjkelra.com (jbk)
- [Discuss] Changing Comcast Modem to Bridged
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