Arris SB6141 connected to switch. How do I find address list of connected devices?

We have a small business with about 8 computers and 2 printers.

Prior to getting Comcast we had AT&T Uverse whose router address was 192.168.1.254. The Uverse modem was connected directly to a Netgear 24 port network switch. All the connections are then sent through the office to the various devices via CAT 5. The addresses of each device are assigned randomly with numbers in the sequence of 192.168.1.xxx. I set up the 2 printers with their own IP addresses like 192.168.1.100 & 192.168.1.150, so that each computer could set them up to print at those specific addresses. Should we lose power, or the machine is turned off, the IP addresses of the printers wouldn't change when the power came back up, thus each person wouldn't have to go in and change their individual printer settings.

So we fast forward to Comcast. I got the ARRIS SB6141 router and Comcast installed it and it is connected to the same Netgear switch. Now, some computers connect and some don't, even though they are attached to the same switch (and they go back to connectivity when I connect the switch back to the AT&T modem). What I'm trying to figure out, (other than why some aren't connecting to Comcast modem) and neither the tech at Arris, nor at Comcast could tell me, is what is the series of numbers that the arris modem will assign to the different devices when they get connected to the internet? I know the Cable modem is 192.168.100.1. Does that mean the computers that connect will have the series assigned randomly like 192.168.100.2 then 192.168.100.3 etc? Also, what are the Subnet Mask and the Deafult Gateway addresses for the Arris modem? I want to again set up the printers and assign them numbers so, should they get turned off, I don't have to go to each computer and change the IP addresses so they can print.

Thanks, in advance, for any help you can give me.

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Accepted Solution

xz4gb8

Problem solver

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117 Messages

8 years ago

carehs wrote, "I got the ARRIS SB6141 router and Comcast installed it and it is connected to the same Netgear switch. Now, some computers connect and some don't, even though they are attached to the same switch (and they go back to connectivity when I connect the switch back to the AT&T modem). What I'm trying to figure out, (other than why some aren't connecting to Comcast modem) and neither the tech at Arris, nor at Comcast could tell me, is what is the series of numbers that the arris modem will assign to the different devices when they get connected to the internet?"

The Arris SB61xx series of cable modems convert between the Comcast coax and your local Ethernet. In use with cable the modem does not supply routing or address assignment to downstream devices. Since you do not have fixed IP addresses, Comcast configures your connection to support one downstream device configured by DHCP from the Comcast server. To use multiple devices with your Comcast Internet service and the SB6141 you must have router and DCHP server downstream from the modem Ethernet port. Then the Ethernet switch can be used to connect multiple devices. The Ethernet switch also does not do IP routing or IP address asignments.

You need this kind of connection path:

Comcast Coax-->[SB6141]<--Ethernet-->[Router]<--->[Switch]<==Ethernet (multiple) to local devices

The Router is the single device connected to Comcast. It may also include WiFi as well as Ethernet for connecting local devices. Connections between the Router and local devices pass transparently through the switch.

The box called the Router generally supplies DHCP for IPv4, SLAAC for IPv6 using a delegated prefix, NAT for IPv4, routing for IPv6, and DNS services. It may also act as a WiFi access point.

I have no experience with or knowledge of Uverse. I will not advise you on choice of Router except to say that I use Apple Airport Extreme basestations for myself and the others I support. Everything about local configuration also applies Xfinity and Charter cable connections. My CBI connection has been in service with the described configuration for over 3 1/2 years with no major problems using both IPv4 and IPv6.

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carehs

New Member

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2 Messages

8 years ago

xz4gb8 - Thanks for your help. I picked up a Netgear Nighthawk wireless router and it pretty much did all the work for me. The IP addresses for the printers came up too, so I didn't even have to mess with them at all either.

Thanks for helping a Newbie out.

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