router won't talk to cable modem 3

[JCrou82]

I have a friend who has optmium online and uses a surfboard sb4100 cable modem. When connected directly to the machine he can get online. He then needed to add a second machine (a laptop) so he figured he'd buy a router (Linksys 4 port with built in firewall, doesn't like xp's or the ISP's firewall) When I connect the XP machine directly to the router, no problem, except the fact that within the status page it doesn't show the machine's ip address. In any event once i connect the modem to the router and do all the resetting, my wan lights on the router don't turn on and the activity light on the modem also don't turn on. We swapped cables and tested them by doing a direct modem-to-machine connection and they passed. This is the second router he's gotten, the last one he replaced because Linksys support said that it had a bad wan link "outlet". Has anyone experienced this before? Any possible solutions? Should I attempt to use a cross-over cable?

Thanks in advance

 

[cdogg]

Quick answer on the crossover cable is NO, that won't help!

Begin troubleshooting without connecting the PC to the Router. All we are concerned about at this point is the cable modem and router - we'll leave the pc disconnected for now.

1) Power off the cable modem and disconnect all cables running to and from it.

2) Power off the router and disconnect all cables

3) Power on the router, and hit the reset button (you may have to hold it in for a few seconds).

4) Once the reset cycle completes, re-connect the cables (Ethernet and Cable ISP connection) to the back of the cable modem. Then connect the Ethernet cable from the modem into the router's WAN port.

5) Turn on the cable modem and keep your fingers crossed.


If the router's WAN lights still don't come on, then it's not the router's fault. Some cable modems have the ability to store the MAC address of the NIC card in a computer. A router also has a MAC address. If the cable modem has a different one stored, then that would explain why it doesn't want to talk to the router. You might have to reset the cable modem (which you can call their tech support for). ~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[bcastner]

Place a hub or switch between the cable modem and the router.

This is a common problem.

 

[JCrou82]

Thank you both for your posts.

bcastner: I'm giving you a star eventhough I already figured this out the day after I placed the post. I got an associate of mine to take a look at it, he's got more experience with routers, switches and hubs than I do. He placed a switch between the router and modem and it works fine. The idea is that the router and the modem can not for some reason unknown to mankind, talk to each other so a switch needs to be introduced and placed in between to "translate" the data.

If anyone has a better or more defining explanation, please feel free to post it here so I can document it correctly in case of any further encounters.

Thank You

 

[cdogg]

Personally, I've worked with Netgear, Linksys, and D-Link routers. I've never needed a hub or switch between the modem and router. That's new to me!

If your router has a WAN port and uses NAT (Network Address Translation), then there should be no need for a hub or switch. As a matter of fact, the Linksys BEFSRxx models have a switch built-in.

Oh well! Glad you got it working, anyway!


~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[smah]

I agree cdogg that the intermidiate switch shouldn't be required.

 

[Newposter]

I have this exact configuration and need no switch. Perhaps it's set up incorrectly. Newposter
"Good judgment comes from experience. Experience comes from bad judgment."

 

[bcastner]

This might, or might, not clarify the hub/switch issue.

Certain cable modem models, the Surfboard from Motorola being one, are known to be problematic on the WAN switch of various SOHO routers, Linksys being one.

In the case of the Surboard and some others, it has been suggested that the voltage of the Ethernet port is too high for the router WAN connection to be reliable.

A more common source of problems is that the modem lacks an auto-negotiation logic, or the firmware logic is faulty. The router as best it can understand things attempts to set a 10bt-half duplex setting for the WAN Port. The modem in turn re-attempts negotiation endlessly.

I have never seen the problem with an ADSL modem.

My own personal suggestion is that the problem can also be cured by talking to your cable provider. As they utlimately control the parameters used by the modem, asking for a specific modality (10-half, or 10-full) to be applied as a configuration setting will also solve the problem.

Best.

 

[JCrou82]

bcastner: that sound like a very stable answer. It is deserving of a star, though I already gave you one. I'll show this to my friend and my associate and see what they do about it. I think though, they are just going to stick with the intermediate switch.


Thanks for the info

 

[cdogg]

bcastner,
Those cases you describe must be rare. I've worked with 2 cable broadband ISP's (COMCAST & Time Warner) and 2 ADSL ISP's (SBC and Earthlink). All 4 ISP's have used a range of modem models in the past including Motorola, Efficient Networks Speedstream, Toshiba, and RCA. Like I said earlier, I've worked with all sorts of combinations with various routers (D-Link, Linksys, and Netgear).

Out of 15 or so people that I've helped in the past, I have yet to see the problem you describe. I'm not saying that it doesn't exist, but it must be extremely rare...


~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[bcastner]

I really do not know how rare it is. I would be willing to bet on the DSLR Forums over the last 3 months I have solved exactly the problem tha is the topic of this thread in the same way: an intermediate hub or switch.

The problem in particular for the Linksys case has become more commonplace with the W54xx series, and for the 2.6 USB wireless device. On the DSLR Linksys forum I would be on the first page alone you will find 3 problems with autonegotiation between modem and router devices.

BTW, You mentioned earlier that the Linksys routers, including wireless routers, are also switches. You really do not want to plug the modem into the switch portion, and a second port looped back to the WAN portion of the device.

My best to all.
Bill

 

[cdogg]

The Linksys routers I was referring to are the BEFSRxx models. They have a built-in switch. I'm not sure what you mean by "plugging the modem into the switch portion". On a BEFSR41 model, for example, you have 6 ports on the back of the router:

1 - WAN port
4 - LAN ports
1 - Uplink port

If I have a broadband modem, I'm going to simply connect the ethernet cable from the modem into the router's WAN port. That's all there is to it.

Again, I don't doubt that you've encountered a problem with a certain type of modem. I just have yet to see it...


~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[bcastner]

I must have misunderstood year earlier post: "
If your router has a WAN port and uses NAT (Network Address Translation), then there should be no need for a hub or switch. As a matter of fact, the Linksys BEFSRxx models have a switch built-in. "

Implying that one could use the switch portion of the router in an intermediate fashion to the router's own WAN port.

Best.

 

[cdogg]

Huh? You're confusing me.

The switch is on the LAN side of the router, not the WAN side. A modem shouldn't need to go through a hub/switch before it reaches the WAN port.

Sorry if I caused all the confusion...




~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[drdebit]

Is it an electronic issue or a security issue, or both that makes it inappropriate to use the switch built into the router if it is necessary to interpose a switch between the router and the cable modem?

 

[bcastner]

It is not a security issue. Best guess is that the modem and router fail to successfully auto-negotiate the speed and duplex mode of the WAN connection.

 

[karlehenry]

i am the associate of JCROU82 and i have been working on this issue,first off, cdogg, i undrestand where you are comming from and i have set up many lynksys routers before and NEVER had a problem like this.. however, after reading bcaster's post i agree with him. i kno wits not a security issue cause i used the linksys router to mask the pcs ip address and yet it still does not work, it only works with teh switch. thanks for the adivce bcaster, you helped solve a mind bogling problem. Good looking out.


karlehenry@aol.com
P2C solutions provider
Computer Consultant/Desktop Specialist/Help Desk Administrator

 

[kennz]

go to the setup page of the linksys router via IE and change the lan ip add of the router to 10.10.10.1.. power down everytheing and power up. the modem. then the router. then the computer. that should work..

 

[kennz]

by the way the default ip add of the router is 192.168.1.1.. ok ...good luck

 

[kennz]

to follow up the issue is that motorola modem caonflict with the dhcp settings with the router and the modem. that is why we have to change the lan ip address of the router.. by the way don't forget to mac clone..