Just curious if anyone knows the answer to this.



I was talking to a pc tech a short while back and we were discussing my networking four computers using a router to cable internet. It is a bit quirky but I will explain my situation.

I get service through Time Warner Cable for the internet. I was on Road Runner but because of FCC issues, Earthlink was allowed to go over the Road Runner/Time Warner lines. I changed over to Earthlink for three reasons. 1: I had been an Earthlink dial-up subscriber for eight years and out of those eight years had rarely had any problems. 2. I had been on Road Runner for 10 months and had already lost service for a total of almost two months during that time not to mention the fact that there is only one maybe two people in the office who seem to have a clue how the hell the cable internet works. 3. The Earthlink was about $20 cheaper per month. We don't like the cable television service and have been with PrimeStar/Direct TV for five years and are very happy with it. Due to this reason, we were way overcharged for cable internet service.

So.... As I was saying before, the pc tech and I were discussing the networking and he told me that he had found cases were Road Runner wouldn't allow more than four computers to be hooked up to the one cable line even though the computers are hid behind the router.

Does anyone have any insight on this? I have four computers hooked up now and may be building one for my husband in the future. If I do build him a computer, he will no doubtedly want to get on the internet so there will be a need for yet another computer to be added to the network only this time, I will have to make use of the hub I was originally using before getting the 4-port.

If the hub is used, wouldn't I need a crossover cable to go from the uplink in the hub to the 4-port?

Thanks for the info. It is really appreciated. As I said, it may be later on this year before I start thinking about adding yet another computer to the house. It isn't like we don't have enough computers already right? :D There are two on my desk but one is for work and the other for play but every time he manages to get on my machine, he crashes it. :(



The question relates to what router you are using connected to the roadrunner modem. The router has one primary purpose relating to the interent. Support the correct NAT translation in the home network based upon the NICs MAC address and fprwarding addresses correctly through internal router, switches, and hubs. I have different problem with my router and the internal NETSCREEN-5 firewall device that supports my NAT.

In your case It depends upon how you connect the hub/switch to the router, do any of the ports autosense, or have buttons to channge fom mdi to x-mdi.


I am not sure about some of the things you are asking but here is what I have and how it is hooked up.

Here is the 4-port router by Linksys:

Each of the four computers have an ethernet card with cat5 going directly into the router. Right now, I am not using a hub. The one I do have packed back is a 5-port hub. It is the workgroup hub. I don't know for sure if it is autosensing or not.

I do know that I had to set up a mac address in the router software. Then, I had to assign each computer a unique ip address.

I have my main machine in the DMZ area. It is also exposed to the internet with certain ports open to make Edonkey work, Messenger, and a couple of VOP programs work. I do run a very good firewall program and antivirus program that have proven to work fine and have even stopped the Nimda virus. The other computers are hid behind the router.

The only problem I have found is that when one of the kids is using their computers, my connection slows way down. I have been trying to figure out a way to assign speed allotments, if you will, to each machine so they won't zap all my thunder - pardon the phrase. It generally isn't a problem because I am online during the day when they are in school and work at night when they are in bed.




Hi Paisley

My name is Ken.

You got a very good Cable Router there. It supports up to 253 unique IP or MAC addresses. Each NIc card has an embedded unique hw address. You do not need to worry about it, but to undertstand that it exists. Any network type device has one ( mac address). Your router can support 253 MAC addresses or computer/IP address pairs. The routers and hubs need to know how to route the messages to the correct computers locally either directly or through another hub/switch. So if you have only 4 ports available (actually 5 if you count the connection to the cable modem) Take a look at this picture.


Now, go unpack the hub you have. It probably has 5 or 6 ports on it. If it has 6, one of them is an uplink port ehich means port 5 is for connecting to a computer and port 6 is used to connect to another switch or router (your case). If it has 5 ports ther may be a small button near one of the ports that switchs the port from standard to cross over. The cross over is used to connect it to your router. It may be a new autonsesing hub that means it does not care what wiring you use, it will figure it out Probably not in your case. So you need to go get that cross over cable to connect the hub and router.

How to tell if it is working. Unplug one of the cable for a computer. Plug in a cable and connect it to the hub. All the lights green we keep going. No lights, let's try the xross over the cable and check it out. Next plug the cable from the computer in into the hub and you are all set.


Thank you so much for that information. I have saved it in notepad on my computer for use at a later time.

I do have a question though. It was my understanding that only one mac address is put into the router page (Mac address clone page) (ie. Does each computer's mac address go somewhere else that I have just missed somewhere?

Right now, I am using the main computer's mac address in the router info spot. The tech at Linksys told me to get that info from going to MS Dos, typing in ipconfig /all. I also obtained the dns numbers from there and plugged them into the XP TCP/IP area.

I also had to disable the DHCP in order to get Edonkey to work but I think XP has a built-in DHCP. I don't know if it is right or not but it is working.



Hi Paisley

Check out the ipconfig /all command for displaying a computers meteotk configuration.

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Documents and Settings\Administrator>ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : kjflt
Primary Dns Suffix . . . . . . . : fisherent.com
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : fisherent.com

Ethernet adapter Docking Station:

Connection-specific DNS Suffix . : fisherent.com
Description . . . . . . . . . . . : Intel 8255x-based PCI Ethernet Adapt
er (10/100)
Physical Address. . . . . . . . . : 00-20-E0-63-21-15
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . :
Subnet Mask . . . . . . . . . . . :
Default Gateway . . . . . . . . . :
DHCP Server . . . . . . . . . . . :
DNS Servers . . . . . . . . . . . :
Primary WINS Server . . . . . . . :
Secondary WINS Server . . . . . . :
Lease Obtained. . . . . . . . . . : Tuesday, January 08, 2002 5:10:33 PM

Lease Expires . . . . . . . . . . : Sunday, January 13, 2002 11:40:33 PM

If you notice the attribute Physical address and the the string 00-20-E0-63-21-15. This is the MAC address of the machine you that one (usually) or more IP addresses are related two.

Routers perform two functions and switches one. Routers (1) act as switches and (2) know where to forward IP packets to the proper Network. Switches keep track of the physical addresses and the IP that are assigned to them and forward the packet. A side note is that if you were running Novell IP/X standard you would be routing my mac address internally whic is why it is more secure and less useful.

Back to your configuration. Your cable company gave you a modem that has a dynamicaly (usually) assigned IP address allocated to the computer connected to it. You were told what the Gateway address and what the primary and secondary DNS names are. Also you were given the names of the mail, smtp, and news servers. Note the roadrunner device in most cases does not have an IP address. Since you have added a router to perform NAT translation, it will now have two IP addresses assined to it. One is the WAN addressed assigned by the cable company to you dynamically or statically. The other is the addressed that the rest of your network will consider as the gateway address (ie All the other compuers in your network will have address ranging from - a gateway address of (the router). Also you will have a net mask of The last number says that any number from 1-255 is local. If any of the first three numbers is different, it is remote. The DMZ port stats that no masking of IP addresses or port numbers are used. Remember each IP address has port numbers assigned to it ranging from 1 to 64K. So the NAT function not only maps IP , it maps the port numbers as well. The reason why you turned DHCP off was so that you did not have to do dynamic port mapping for in bound transactions. There is a Networking and Firewall for dummies books. I own the books also. I will remain always avaiable for help. Ken



Thank you so much for that. I have learned so much this past year about networking. I had worked on the internet, with computers, and with many software programs for about 20 years now but until this past March, had never directly worked with any type of networking. It was sort of trial and error, call tech support, trial and error, call tech support. My the grace of God and others like yourself, I have been able to get a fully functional network going with very few problems with the exception of what I believe is just plain old bottlenecking of the bandwidth.

I need to get a copy of those books for my mother. She has only been messing with computers for the last year or so but I did set up an anti-virus program with autoupdating as well as a firewall program on her computer. She is not networked yet but it will be coming in the future as she and my step-dad are in the process of adopting two children - my step-dad's grandchildren (long story). When they are ready, I'll be setting up her's as well. I will probably have her go with the D-Link network kit as I have read it has some software that can control the times other computers on the network can get on the internet. It's not much of a chore for me because I am up nights working and if one of the kids are online, I can hear the typing or mouse clicks. (BTW, I am visually impaired at legally blind status but do have some light perception but my hearing is excellent. :D ) If I get the books for my mom and have questions, I can have her read through it for me or we can have the binding cut off and the entire book copied and I can scan it into my computer so I can read it. I bought her the Windows for Dummies book a few years ago and she loved it. I even gave out a few copies to some friends of mine for Christmas presents one year. Hey, may sound tacky but my phone actually didn't ring very much for a few months. LOL!