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Wed, Oct 14, 2015 4:00 PM

Need Help with Comcast BWG (new Cisco DPC3941B) in Bridge Mode, 5 static public IPv4 addresses

I'm helping set up a small business office in metro Atlanta, they're provisioned with a Comcast Cisco DPC3941B and a 5-block of static IPv4's. We're consistently measuring 115+ Mbps downstream in their location - smokin' fast, very sweet. We plan to have the Comcast BWG set up in Bridge Mode, directly feeding a Dell SonicWall NSA250M firewall that's our primary router and local DHCP server.


The problem is that our cloud-based VoIP provider wants to install an Edgewater Networks 4550 ESBC/MVG to manage their over-the-top VoIP services. This box has a 30Mbps max throughput, and it will throttle our bandwidth if we add it in series between the BWG  and the firewall. The functionality and capabilities of the Comcast BWG in Bridge Mode is unclear to me and poorly documented at best; I can't find a shred of documentation to help me. I'm particularly confused about the visibility of our 5 static IP addresses to the Internet via the BWG, how does that work exactly??? How exactly are those devices accessed from the Internet when the BWG is in Bridge Mode?


I happened to notice that both LAN Port 1 and LAN Port 2 appear to be active when the BWG is in Bridge Mode (LAN Ports 3&4 are disabled).. I was thinking that we could connect our firewall/router (with its own static IPv4) to LAN Port 1, and the Edgewater MVG (with its own static IPv4) to LAN Port 2, effectively using the Cisco DPC3941B BWG as a 2-port switch (??). Advice? Suggestions on a possible connection scheme?



Accepted Solution

Trusted Forum Contributor


1.4K Messages

5 years ago

Hello GT_Dan and welcome,


First, no industry standard internet gateway operating in True Bridge Mode (TBM) will work with any static IPs. This is due to when in TBM ALL staticIP, LAN DHCP, Natting, etc. is totally disabled with the ONLY exception being that the WAN DHCP address(es) will be provided to a Firewall (FW), Controlling router (CR), etc.


So, I would recommend that you run your DPC in normal staticIP addressing mode (not in TBM) and have your internal DPC LAN DHCP Server disabled or in passthrough / pseudo bridge mode, or whatever you want to call it. This will allow you to avoid any LAN DHCP Server conflicts with your FW, CR, etc. Now, when you disable the DPC LAN DHCP this also disables both your private and public wifi.


You will be able to use one static IP routable address for your Firewall and another for your Edgewater Networks 4550 ESBC/MVG (EN4550) and both interconnected into any LanPorts 1-4 via ethernet cable. This parallel interconnect will not allow the EN4550 to have any impact on load balancing your FW ports / devices data processing through as long as you have load balancing disabled, of course.


Hope this helps you out.