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Strict NAT? Bridge Mode? What is IP Passthrough? Can I enable on my Arris BGW210 or like router?

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Strict NAT? Bridge Mode? What is IP Passthrough? Can I enable on my Arris BGW210 or like router?

BGW210backColor.pngBGW210frontColor.png

 

The Arris BGW210-700 is an advanced residential gateway that supports VoIP, IPv6, video delivery, security firewall, and extensive remote management features. 

 

The BGW210-700 Broadband Gateway delivers robust video, primary line telephony, and high-speed data over broadband networks via high-speed Internet connectivity.

 

The four Gigabit Ethernet ports can be separated into different services allowing the configuration of dedicated ports for data. It is designed for advanced DSL network service deployments and supports Quality of Service (QoS) and IP Passthrough.

 

Determining the Business Need

Business customers sometimes state that they need DSL/Broadband CPE that can be configure or placed into a Bridged Mode where they are putting other CPE behind the DSL/Broadband CPE. Many times, these customers can be better served with a configuration known as IP Passthrough. The below information explains the difference between IP Passthrough vs Bridged mode and provides instructions on how to configure the Arris BGW210-700 Internet Gateway for IP Passthrough.

 

IP Passthrough means the AT&T supported CPE device terminates the DSL, authenticates with the network (Receives a WAN IP) and shares that IP address with a single device connected to the AT&T supported CPE equipment. This configuration is often times suitable for a business customer desiring to connect third party equipment to AT&T supported equipment. The IP Passthrough configuration still allows AT&T support groups to access the AT&T supported equipment while allowing end-users to connect third party equipment in a configuration they desire. The IP Passthrough configuration will only allow one connection to AT&T supported equipment to be "unfiltered" or pingable from the WAN or internet side of the AT&T equipment (does not support multiple pingable connections).

 

The IP Passthrough feature allows a single PC on the LAN to have the AT&T Gateway's public address assigned to it. It also provides port address translation (PAT) or network address and port translation (NAPT) via the same public IP address for all other hosts on the private LAN subnet.

Using IP Passthrough, the public WAN IP is used to provide IP address translation for private LAN computers. The public WAN IP is assigned and reused on a LAN computer.

 

Note: Remember to make a copy of all current IP settings before proceeding.

 

Configuring IP Passthrough:BGW_IP_Passthrough_Screen.jpg

Run your Web browser application, such as Firefox and Chrome, from the computer connected to the Arris BGW210-700.

 

 

  • Click the IP Passthrough tab and configure your settings.

 

 

Dynamic host configuration protocol (DHCP) address serving can automatically serve the WAN IP address to a LAN computer.

 

When DHCP is used for addressing the designated IP Passthrough computer, the acquired or configured WAN address is passed to DHCP, which will dynamically configure a single servable address subnet, and reserve the address for the configured PC's MAC address. This dynamic subnet configuration is based on the local and remote WAN address and subnet mask.

IP Passthrough Mode.jpg

 

  • The two DHCP modes assign the needed WAN IP information to the client automatically.
    • You can select the MAC address of the computer you want to be the IP Passthrough client with fixed mode or with first-come-first-served dynamic. The first client to renew its address will be assigned the WAN IP.

 

  • Manual mode is like statically configuring your connected computer. With Manual mode, you configure the TCP/IP Properties of the LAN client computer you want to be the IP Passthrough client. You then manually enter the WAN IP address, gateway address, and so on that matches the WAN IP address information of your AT&T device. This mode works the same as the DHCP modes. Unsolicited WAN traffic will get passed to this client. The client is still able to access the AT&T BGW210 device and other LAN clients on the 192.168.1.x network.

 

  • DHCP Lease: By default, the IP Passthrough host's DHCP leases will be shortened to two minutes. This allows for timely updates of the host's IP address, which will be a private IP address before the WAN connection is established. After the WAN connection is established and has an address, the IP Passthrough host can renew its DHCP address binding to acquire the WAN IP address. You may alter this setting.

 

  • Click Save. Changes take effect upon restart.

 

Note: IP Passthrough Restriction

Since both the BGW210 Internet Gateway and the IP Passthrough host use the same IP address, new sessions that conflict with existing sessions will be rejected by the BGW210. For example, suppose you are working from home using an IPSec tunnel from the router and from the IP Passthrough host. Both tunnels go to the same remote endpoint, such as the VPN access concentrator at your employer's office. In this case, the first one to start the IPSec traffic will be allowed; the second one from the WAN is indistinguishable and will fail.

 

If you need further assistance with your IP Passthrough setup and configuration contact ConnecTech Support.

 

Jared, AT&T Community Specialist

 

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*I am an AT&T employee, and the postings on this site are my own and don't necessarily represent AT&T's position, strategies or opinions.
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Message 67 of 176
Tutor

Re: Arris BGW210-700 Passthrough mode

Hi darronia,

 

Sorry for the late response - you would typically get this error if you are using a Subnet mask that is not identified by a router - Check to make sure you are using 255.255.255.0 subnet or 255.255.0.0; I am guessing the subnet on the airport extreme may be using 255.255.252.0 which may be the cause of the issue. I am no network expert but i hope this helps.

 

Regards,

Message 15 of 176
Mentor

Re: Arris BGW210-700 Passthrough mode

I cannot get this to work for me at all. I have a Juniper SRX345 that I want to be the main router/DHCP server for my home network clients. At the moment I have IP Passthrough on the BGW210-700 configured with the cascaded router settings of:

 

Cascaded Router: On

Cascaded Router Address: 0.0.0.0

Network Address: 172.32.31.0

Subnet Mask: 255.255.255.128

 

I have an ethernet cable plugged into ge0/0/0 of my SRX with dhcp enabled.  I have turned OFF the wifi, DHCP, packet-filters, firewall on the ATT provided router and still the SRX isn't receiving any DHCP passthrough address on the ge0/0/0 (outside interface). Having the ATT in bridge mode is exactly what I want but it's not working for me.  Additionally points, following the instructions above, I am unable to add my SRX's mac to the Passthrough screen as this is an field I cannot edit. I can only say PASSTHROUGH YES and then there's a MANUAL choice but that's it for this screen.  Any help would be greatly appreciated. Right now I'm still using my Comcast with another SRX until I can ge this guy going. Paying double the prices monthly isn't favorable.

Message 16 of 176
Tutor

Re: Arris BGW210-700 Passthrough mode

I'm also having trouble setting this up with an AirPort Extreme. If someone can please provide step by step instructions, that would be appreciated. I tried the steps from an earlier post, but I keep getting an error saying Cascaded Network Router address must be WAN side subnet.
Message 17 of 176
Mentor

Re: Arris BGW210-700 Passthrough mode

You dont need cascaded router. Please turn that feature OFF. All you need is passthrough ON. If you're in the firewall screen and find that the field are not able to be edited, RESET the router back to factory resets (this was my issue) and go back and turn on IP PASSTHROUGH again. Those fields should now be editable.  Turn off MANUAL and use the DHCP option to pass the IP to your router.  You can put your routers MAC address there if you like. I didn't do that, it saw it on the other end and I just chose my device. YOU MUST LEAVE DHCP TURNED ON WITHIN HOME NETWORK LAN & SUBNET (I might be getting the exact name wrong as I'm not looking at it at the moment, but the place you would configure DHCP for clients if you connected them to the ATT router is where I am talking about). If you dont have DHCP turned on, then IP Passthrough will not work. What I did was just have the scope set to 3 because I'm a paranoid Network Security guy, lol. This feature allows the PUBLIC IP that would have normally gone to the ATT router, pass-through to your connected router.  This is my setup and now it's working great.

Message 18 of 176
Tutor

Re: Arris BGW210-700 Passthrough mode

Where did you set the scope you're referring to?

Thanks for the instructions!
Message 19 of 176
Contributor

Re: Arris BGW210-700 Passthrough mode

Just installed fiber (1000 gig) internet in Dallas. New gateway used is BGW 210. Was told this will probably be the main router used for future installs. Don't get nearly as good range/coverage as I did with older Pace 5268AC and copper line. I do get 950mb speed up and down when connected to the new router but wifi signal strength measured in -db falls off very quickly to lost connection within 30 feet. I've tried various router placements within my 2 story home with the idea that placed as central and as high would be optimal. Still no sweet spot to achieve workable signal strength. One question is what kind of WiFi protocol does it use (b/g/n/ac) and does it employ MU-MIMO technology? It's hard to know what I'm dealing with with no documentation or user guide. All that said I think I'd like to set this router up in pass through mode and try an ASUS RT5300 router to improve the range. I have read some posts directed at this but could you detail it out specifically for the technically challenged ike myself. I would like to connect some devices directly to the BGW Ethernet ports but pass all WiFi functions off to the ASUS. Is this possible and how do I set this up. Your help would be most appreciated.
Message 20 of 176
Contributor

Re: Arris BGW210-700 Passthrough mode

I'm also having some trouble with the cascaded router option.  Can you detail the exact ip addresses you used?

 

My Arris BGW210 is set at 192.168.0.1 / 255.255.255.0

 

What should I plug into my router?  It's set at 192.168.1.1 / 255.255.255.0, but that definitely won't work. 

 

I tried changing the router to 255.255.254.0 or a 10.x IP address, but no luck.

 

Apparently, I don't understand subnetting.

Message 21 of 176
Tutor

Re: Arris BGW210-700 Passthrough mode

Hi,

 

You will need to set the cascade option only if you plan to have another router along with the ATT router as your main DHCP. But if you want the ATT router to act as just a model and not a DHCP and instead want your personal router to be your DHCP then you would need to set the passthrough option under Firewall | IP Passthrough | allocation mode set to passthrough | Passthrough mode set to fixed and from the drop down you would select the router name or enter the MAC ID of your router. 

 

I hope this helps.

 

Regards,

R

Message 22 of 176
Mentor

Re: Arris BGW210-700 Passthrough mode

You do not need the cascaded router option for any reason. Just turn it off & follow my previous instructions. Those of you asking about the scope used, that has no bearing. You can use whatever scope you want. Ip pass-through is all u need. Set your routers Mac address on that screen & you're all good. The public IP that would normally be the WAN interface of the att modem will now be assigned to the interface of your firewall /router that is plugged into your att modem. Turn on DHCP on the att modem regardless of whether you'll use DHCP on the att router or not. You'll need it. Use a different scope for your LAN IPs DHCP scope.
Message 23 of 176
Contributor

Re: Arris BGW210-700 Passthrough mode

Thanks, I'll give it another try next weekend.  One problem I kept having after I gave up on the Cascaded Router option, was that my personal router kept fussing that the WAN and LAN addresses 'overlapped.'   Not sure what that meant either.

Message 24 of 176
Mentor

Re: Arris BGW210-700 Passthrough mode

Overlapped means you're using conflicting IP addresses but that should NOT happen so you're definitely doing something wrong. The WAN IP that is "pass-through" the ATT modem is PUBLIC (which is why it's used on the Internet). Unless your LAN IP address scope is public, which it should NOT be, that shouldn't be an issue.  Use 192.168.1.100/24 or some other private IP space on the LAN side. On your router's WAN port (the one that connects to the LAN port on the ATT modem/router) should be configured as a DHCP-client that it will receive the public WAN IP that is passed-through to it. Hope this helps.

Message 25 of 176
Tutor

Re: Arris BGW210-700 Passthrough mode

Hi,

 

I am guessing you get this error on the router - the WAN port on the router would be a LAN IP address of the DHCP coming from ATT router. Make sure the LAN on your router is not the same as the LAN on your ATT router. For example the default IP address on the ATT is 192.168.1.x - and the default IP address on your router may be the same. change that to 192.168.2.x and that should resolve this issue. 

 

I hope this helps.

 

Regards,

R

Message 26 of 176
Contributor

Re: Arris BGW210-700 Passthrough mode

I just had ATT internet installed and wanted to put the BGW210 into passthrough mode.

I already have an Apple TimeCapsule that has all my port forwarding and IP reservations setup.

 

I am switching from Comcast.

I followed all the steps numerous times and could not get the TC to see the outside internet.

 

I finally found a solution but not sure if it will continue to work.

 

I changed pass-through to ON

I changed to DHCPS Fixed and entered the TC ethernet mac address.

I left the DHCP Server setting to defaults since my TC network uses a different subnet than the default so they don't conflict.

What I had to do differently is the following:

In the TC Internet settings, I had it set to DHCP to get the external IP and router.

This worked fine on the Comcast setup.

But would not work for ATT setup.

I changed it to Static and manually typed in the IP address I see in the BGW210 settings.

I typed the same address with a .1 on the end for router.

 

I now have outside connection!!

My concern is if ATT changes my IP address, I will need to change the TC address to match.

 

How do I access the BGW210 on a different subnet from my computer?

Currently I plug a laptop directly into the BGW210 in order to access the configurations.

 

bdog

 

 

Message 27 of 176
Mentor

Re: Arris BGW210-700 Passthrough mode

That's not going to work if they change your ip. Make sure the port you've
plugged into the TC from your Att Modem is setup as a DHCP client.
Message 28 of 176
Contributor

Re: Arris BGW210-700 Passthrough mode

I gave up on trying to use 'Cascaded Router'.

 

I just disabled all wifi and set ip passthrough to DHCPS-fixed for my Asus router to be the wireless for the house.

 

I left everything else on the Arris modem/router the same (DHCP server etc).  I am using all wired connections directly off of the Arris as I am getting much better speed than off of my Asus router.

 

Anyone with more knowledge than me see any problems (security or otherwise) with this?

Message 29 of 176
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