My network is set up like this:

Charter cable modem - my Netgear cable modem used as a wireless router -
Airlink secondary router used as a secondary wireless access point.

Things were so easy when I used my personal cable modem hooked up to Charter
internet. Then Charter said I had to user their modem except it didn't have
built in wireless capability. I managed to install my cable modem, Netgear
CG814WG, as a wireless router. I also added a second wireless router, an
Airlink 101. All was fine. I could access either wireless network from
either wireless router and also access the settings from any computer in my
system. Then one morning, the power supply for the cable modem quit.
Unfortunately, not realizing it immediately and unable to figure out why it
was nonresponsive, I hit the reset button. I waited for the lights to come
back on but they didn't. Then I checked the power supply, nothing. I
couldn't find another power supply and I was unable to easily open the
adapter to repair it so I pulled it out of the system. The Airlink router
became my main router and that's where things remained. Then I looked
through my box of orphaned power supplies. I found an Epson power supply
which I think fit one of my old zip drives. The voltage and current ratings
matched the burned out supply so I decided to put the network back the way
it was (see line 2 of this post).

Now for the part I can't figure out. If I plug the Netgear cable modem (this
modem has no internet port, just four Ethernet ports) into the computer
without hooking it up to the modem, like this:

Netgear wireless router/cable modem --Computer

I can access the router's menu and settings. If I then plug the Ethernet
cable from the Charter modem to my Netgear modem/router like this:
Charter modem -- Netgear modem/router -- Computer
it will work ok. Now I run ipconfig (Windows XP) and the ip address shown is
my internet ip address, not the router ip address. Sometimes I'll restart
the modem and then the correct router address will show up but then the
internet connection will not work and then I can't access the router
settings either. What the heck is going on here?

Thanks for your reply.

--
David Farber
Los Osos, CA

I don't quite understand your configuration, but I'll add a few things.

private IP address, Usually 192.168.x.x..or 10.x.x.x and one other.
public IP address - The one the internet knows of

NAT - Network address translation. This part of the router. That makes it appear that your on the Internet with the public IP, Incoming ports on a port to port bases are routed to the proper private IP,

DHCP: Dynamic Host Configuration protocol - It CAN provide name server info,
Your router's private IP can be the name server relay. The name server allows you to use names for IP addresses,

It can reserve certain address for automatic generation of private IP addresses.
There cannot be more than one DHCP server for the subnet, Static IP's need to be excluded from the pool. A "lease" for a specific amount of time is associated with the address.

Certain devices behave better with fixed IP addresess: e.g. Router, printers

That said, there are two ways to "bridge" a network and I;m only going to talk about one way. One allows you to be able to see the cable modem, and the other doesn't.

If you place the cable modem in "bridge mode", by using a direct connection, it just relays traffic from network and it has a public IP, but not a private IP.

In DSL, things get complicated as to where a ping response comes from. It may not include the wiring from the DSLAM to the premises.

The only way to see my modem's config pages in bridge mode is to connect it directly. I set it to a static IP of 192.168.1.1, but my network is 10.10..0.x.

There is another address called the MAC address and that's called the Media Access Control, Think of it like latitude and Longtude, Every adapter gets assigned a unique one at the factory. The wireless adapter has one and so does the wired adapter on your PC. These addresses are written on the box and adapter. In the form of AA:BB etc for IPV4. Sometimes the : are missing.

It's this addressees that the cable company has associated with your account and credentials. You put another cable modem in it's place, the MAC address doesn't match and it doesn't work. Since the lines are physical on a DSL system, the MAC authentication isn't used.

Yes, the cable modem company can be told that you have another modem and make it work, but they have also customized their router;s firmware to be able to run tests.

So, some routers offer the ability to "clone" mac addressees. This allows your new modem to masquerade as the real cable router.

Earlier I did say that every MAC address is unique. The uniqueness is by routeable network, So, as long as you don't duplicate a MAC address on your private network, your OK.

I will be running at some point a very unique configuration and some of it's in place. My DSL modem is within feet of the demarc point and the wireless is in the center of the basement. Wireless will eventually be wireless AC with a repeater. I can't then use a any DSL modem with wireless capabilities.
Their modems limit the 10baseT ports to 100 mb/s and the wireless ports to 300 mb/s. I have a RAID server on a Gigabit ethernet.

Ron D. wrote:
I don't quite understand your configuration, but I'll add a few
things.

private IP address, Usually 192.168.x.x..or 10.x.x.x and one other.
public IP address - The one the internet knows of

NAT - Network address translation. This part of the router. That
makes it appear that your on the Internet with the public IP,
Incoming ports on a port to port bases are routed to the proper
private IP,

DHCP: Dynamic Host Configuration protocol - It CAN provide name
server info,
Your router's private IP can be the name server relay. The name
server allows you to use names for IP addresses,

It can reserve certain address for automatic generation of private IP
addresses.
There cannot be more than one DHCP server for the subnet, Static IP's
need to be excluded from the pool. A "lease" for a specific amount
of time is associated with the address.

Certain devices behave better with fixed IP addresess: e.g. Router,
printers

That said, there are two ways to "bridge" a network and I;m only
going to talk about one way. One allows you to be able to see the
cable modem, and the other doesn't.

If you place the cable modem in "bridge mode", by using a direct
connection, it just relays traffic from network and it has a public
IP, but not a private IP.

In DSL, things get complicated as to where a ping response comes
from. It may not include the wiring from the DSLAM to the premises.

The only way to see my modem's config pages in bridge mode is to
connect it directly. I set it to a static IP of 192.168.1.1, but my
network is 10.10.0.x.

There is another address called the MAC address and that's called the
Media Access Control, Think of it like latitude and Longtude, Every
adapter gets assigned a unique one at the factory. The wireless
adapter has one and so does the wired adapter on your PC. These
addresses are written on the box and adapter. In the form of AA:BB
etc for IPV4. Sometimes the : are missing.

It's this addressees that the cable company has associated with your
account and credentials. You put another cable modem in it's place,
the MAC address doesn't match and it doesn't work. Since the lines
are physical on a DSL system, the MAC authentication isn't used.

Yes, the cable modem company can be told that you have another modem
and make it work, but they have also customized their router;s
firmware to be able to run tests.

So, some routers offer the ability to "clone" mac addressees. This
allows your new modem to masquerade as the real cable router.

Earlier I did say that every MAC address is unique. The uniqueness
is by routeable network, So, as long as you don't duplicate a MAC
address on your private network, your OK.

I will be running at some point a very unique configuration and some
of it's in place. My DSL modem is within feet of the demarc point and
the wireless is in the center of the basement. Wireless will
eventually be wireless AC with a repeater. I can't then use a any
DSL modem with wireless capabilities.
Their modems limit the 10baseT ports to 100 mb/s and the wireless
ports to 300 mb/s. I have a RAID server on a Gigabit ethernet.

Hi Ron D,

Sorry for the delayed reply. You packed a lot of good information in there.
My configuration, which was working at one point, is like this:

Starting from the coaxial wire from the wall:
The coax goes to the ISP provided Cisco cable modem. My ISP now prohibits
customer owned modems so that's why I'm using theirs and not my Netgear box.

The ethernet cables wired from the ISP provided cable modem to my previous
cable modem which is a Netgear cable modem gateway. The model number is
CG814WG v3. I only want to take advantage of the wireless capability of the
Netgear device as there is already a cable modem in place.

From the Netgear box, there is an ethernet cable going to my Airlink 101
wireless router into the WAN port and that functions without any problem.

As I said before, I cannot get internet access from the Netgear box when the
default ip address/gateway is 192.168.0.1. After some experimenting within
the *Netgear gateway/setup menu*, the ip address for the Netgear gateway
flips to the ip address that is assigned by the ISP (that's what I see when
I run ipconfig in XP). But once that happens, I am unable to access the
Netgear setup menu but I am able to get internet access.

Ideally, I'd like to return to the condition where each router/gateway has
its own ip address, be able to access both devices' (Netgear and Airlink)
setup menu, and get internet access.

Thanks for your reply.

--
David Farber
Los Osos, CA

I changed providers and had issues especially
during the changeover when I wanted to switch
back and forth.
Finally figgered it out.
Put the ISP modem in IP passthru mode.
It doesn't do anything but take the ISP
input and stuff it into the output.
I do all the wired and wireless routing
in MY router plugged into the modem.

The modem shows up in two places.
The External IP address presented by the ISP and
the configuration address at 192.168.15.1
presented to the WAN port on my router.
I can configure my router at 192.168.1.1
and the modem at 192.168.15.1. My router
is responsible for DHCP, but I use address reservation
so everybody has a stable IP address.
Another secret is to use a specified destination
MAC address for your IP passthru instead of automatic.

Got rid of all the multiple natting and address
mixups that I had. Now, I can plug stuff in and out
at most every level and it just works without any address
conflicts.

When I was considering switching to FIOS, I was assured
by the guru that I didn't need their modem at all. I could
plug mine directly into the FIOS box on the wall. Have not
tried it tho.

On Saturday, January 3, 2015 11:19:53 AM UTC-8, David Farber wrote:

Starting from the coaxial wire from the wall:
The coax goes to the ISP provided Cisco cable modem. My ISP now prohibits
customer owned modems so that's why I'm using theirs and not my Netgear box.
....
Ideally, I'd like to return to the condition where each router/gateway has
its own ip address, be able to access both devices' (Netgear and Airlink)
setup menu, and get internet access.

You need to detach the routers other than the ISP-supplied main router, and program
it/them to extend the existing DHCP services of the new main router instead of
hosting their own local network(s). Or, you need to pick one main router,
and change the ISP-provided unit to be a transparent bridge to that main router.