On 12/30/18 10:49 AM, Dan Ritter wrote:
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.
According to the research I've done there are only two ip address options
for setting up the modem in bridge mode. 10.0.0.1 or 192.168.100.1.
My current network subnet mask is 255.0.0.0 for the dozen or so devices that
have static IP's. I do not provide any services outside the local LAN but
within I have a backup server that serves a number of devices.
As I understand it the modem IP in bridged mode wants to be on a different
subnet that the internal LAN which would lead me to believe that the 192
prefixed IP address would be the choice, this is question #1
Once I've setup the modem with the correct IP then will the router now
become the gateway?
I have the Cisco DPC3941T modem, has anyone on here set up the bridge
themselves, I see the option in the management GUI, or per my web searching
this change can only be done correctly by the right Comcast personel
remotely?
Well that's the gist of it, did I leave out anything?
You've got some confusion in there.
Yes, I set this network up around 2001 with the help of
someone else that new networking better than I.
1. NAT has to be handled by a router which has at least one
outside address and at least one inside address.
/Which would now be my router in bridge mode./
2. DHCP can be done by any device on the inside.
3. A bridge operates at the ethernet level, not the IP level.
So once it's in operation, you pretend it's a chunk of wire:
your router connects to the bridge and uses the Comcast
assigned outside address(es), and connects to your internal
network with internal address(es).
/So the router LAN address will now become the gateway
address on my internal network?/
A subnet mask indicates how large a chunk of the IP space should
be considered as local. You've got 16.7 million addresses
considered local right now...
/Yes, I only learned this later after I had made all these
other static decisions/
The net says:
Cisco DPC3941T modem
1) Press and hold reset button on back of gateway for 30
seconds, this will reset the gateway back to the factory
defaults..
2) Connect a computer to ethernet port #2 on the back of the
gateway.
3) After the gateway boots, verify computer has connectivity,
connect to gateway @ 10.0.0.1
4) Change the gateway's login password, disable both private
wifi networks, set ipv4 and ipv6 firewall to custom mode and
select option disable/none.
5) Set Gateway > At a Glance > Bridge Mode to Enable. When you
see the timer screen pop up, you can disconnect the computer
from the gateway as it is rebooting. the reboot can take 3 - 5
minutes.
6) Connect your router to the gateway ethernet port #1, on the
router make sure that the WAN / Internet link is set to disabled
or off.
7) Once the gateway completes it's boot cycle, enable the
Internet WAN on the router. The router should now have the IP
address issued by Comcast.
8) Configure the router as you see fit.
Hope that helps.
-dsr-
Thanks Dan, I did see the instructions on the net of the
steps you outline here, but out of context of my network.
DD-WRT has a lot of helpful information on their site and
forums and I am confident once the modem is in bridge mode I
can implement a network more tailored to our needs including
a VAP to get our frequent guests off our local LAN.
Jim
--
Jim Kelly-Rand
j...@kjkelra.com
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