Equipment (Modems,Gateways)
Modems, Gateways, and Networking Devices
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Bridge mode on a CMCD3G-CCR modem, conflicting information

My shiny new comcast internet has ceased to work following a local outage. 

 

I have a Netgear FVS318N router sitting behind a CMCD3G-CCR modem, the router and modem coexisted perfectly post install (on friday), now, post outage (monday) they refuse to see each other.  When the installer was here I specified that I needed no wireless, and the modem in bridge mode, to replicate the status of our soon to be replaced DSL setup.  Sadly I did not confirm this to be so before they left so I am assuming the modem was originally in bridge mode.

 

Now I get to deal with the absolutely delightful Comcast phone support who:

 

1.  Cannot tell me if the modem was ever in bridge mode, or if I ever requested it in the first place.

2.  Tell me that I cannot have the modem in bridge mode unless I have a static IP address for an extra $15 per month.

 

And yet I read in these forums that you cannot have this modem in bridge mode if you have a static IP address.

 

So which is it?  Can I have my bridge mode, or not.

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Trusted Forum Contributor

Re: Bridge mode on a CMCD3G-CCR modem, conflicting information

What you've read on the forums is correct, you can only have bridge mode turned on if you DO NOT have a static IP. Bridge mode turns the SMCD3G into a "Dumb" cable modem, meaning that it will pass a WAN IP address via DHCP to any connected device(s). All internal routing/firewall functions of the SMC are disabled.

You can tell which mode you are in by looking at your Netgear routers WAN IP; if it is within the subnet 10.1.10.x/24, then the device is in standard mode. If it is any other numbering (eg "68.52.33.103") then it is in bridge mode.

 

By "refuse to see each other" , what exactly do you mean? Do you not get a link light when you plug in the ethernet cable between the SMC and the Netgear? (If so, then you have a hardware problem, and 1 or more pieces of equipment will need replacing).  Or, do you have link lights, but no connectivity?

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New Member

Re: Bridge mode on a CMCD3G-CCR modem, conflicting information

Thanks for your reply.  I feel I owe the forum the resolution to my sorry tale.  Comcast responded magnificently to my issue, the following morning an engineer remotely put the modem into bridge mode (it had been in standard mode), and before I could reboot my router a second engineer arrived and did it for me.  It worked OK for a while, then went out again.  The resulting fix (which was a router issue) takes a little 'splaining:

 

The precipitating problem was periodic brief outages caused by a couple of bad boards on Comcasts end.  The issue was an intermittent one and it took them quite a while to track it down, it seems that they sorted it all out on their end.  My problem was that the router would be fine, then we would lose connectivity, reboot the router, connectivity for a while, then no connectivity etc etc.

 

So based on the fact that there was always a sound hardware connection between the two boxes (Tested the cables, checked the link lights on both boxes), I trawled the router support site and found a known issue with the router hanging when the modem drops a connection, and not reestablishing a connection without a reboot.  This was a "feature" added to the router via the unintended consequence of a firmware upgrade.  So I rolled back the firmware on the router, restored settings and rebooted both modem and router and everything has been chugging along nicely ever since.

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Community Manager
Community Manager

Re: Bridge mode on a CMCD3G-CCR modem, conflicting information

Hi Bonegrubber.  Thank you for the update.  Good to know that this issue is now resolved. We appreciate you sharing your experiences with Comcast products and services with the Forum Community.

 

Thank You

 

 

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