Linksys BEFSR41 with Time Warner Roadrunner

[jfguerra]

This is a long email so I apologize but I felt I needed to give you as much background as possible.

I have 2 PC's at home running Windows XP. We use Time Warner's Roadrunenr cable modem service. Whenever I connect any of the 2 PC's directly to the cable modem, the speed which web pages load is incredibly fast.

About a year ago I put in a Netgear Web Safe Router model RP114 to network my PC's. The router was in the basement connected right next to the cable modem (a Toshiba PCX100U) since the CAT 5 cables from 4 different places in our home terminate in a corner of our basement (I have CAT 5 jacks in the 4 locations). The basement remination point is about 75 feet away from one of the jacks on the first floor. It seemed to work fine and while I did notice a slight degradation in response time from web pages on the Internet, it wasn't a big deal.

A few weeks ago my router got fried during a lightning storm. I got a new Netgear router, only this time it was a more advanced model (RP614). The placed the new router also in the basement, next to the cable modem. The response time was EXTREMELY slow. I talked to the technical support people, trying several things such as the MTU size. This did not work. I gave up and got a Linksys BEFSR41 Cable/DSL Router with 4 ports (also placed it in the basement). My response time is even slower now. We tried changing MTU sizes, setting aside a specific range of ports for the web sites I was trying to access, enabling the DMZ, etc., etc., etc. Nothing worked.

On a whim, I brought the router next to my PC on the first floor. I connected my LAN card output to one of the BEFSR41 ports and connected the output port of the CAT 5 jack next to my PC. In the basement, I hard wired this specific jack output directly to the cable modem. AMAZINGLY, the speed was not back to its blazingly fast mode! In other words, I moved the router up next to me PC and it seemed to have solved the problem! I thought that MAYBE I had changed some configuration parameter by accident and that it would work in the basement now. It did not. I brought it back up and it worked again!

The only logical issue that comes to mind is that the Linksys router has a limit to the cable length I can use to go from my PC to the router itself (when it's next to my PC it's about 5 feet away....when connectd in the basement it's about 75 feet away). I know the signal from my LAN card is going through the 75 feet because the cable modem is in the basement and when I hard wired it to my PC 75 feet away it worked just fine!

Any ideas?? Thanks in advance for any advice!

 

[opediggitty]

Here is my best guess. I am pretty sure that it is an issue with your cabling but like I said I am guessing as to exactly where it would be. I think that the 75 ft run of cable from the room to your basement is either bad or the connectors are bad or, what I really think that it is, is you are using CAT 3 and not CAT 5. That is what would make the most sense because the connection from your cable modem to your router, when next to your PC, is a 10Mb connection where when you have the router in the basement the connections upstairs to your PC's is 100 Mb and if that cable is CAT 3 or is damaged in some way that would take more of a toll on a faster link like the 100Mb. Let me know if this makes any sense to you or not.

 

[bcastner]

The difference is the cable length between the modem and the router.

Your modem is to blame, it is very sensitive to electrical interference of any kind.

The advice in an earlier thread here was to place a 50-75' length of Cat5 between the modem and the WAN port to eliminate autonegotiation errors and interference issues.

 

[jfguerra]

Thanks for both of your ideas. Yes, I understood what both of you suggested. As an experiment, I strung Cat 5 cables (all around the floors of my house) to the basement and connected the router downstairs and then to the cable modem. It worked!

However, I did check my existing wiring and it is CAT 5 wire so I am going to assume at this point that the connectors are not properly installed (would that be a valid assumption?).

I'll change them and see what happens. If it works, problem solved! If not, I may have to rip out the current CAT 5 wiring and replace it.

In any event, you both got me going in the right direction. Thanks again!

 

[bcastner]

If you have a spare switch around, try modem to switch, and then switch to WAN port on the router.

 

[jfguerra]

One more thing. I am assuming that any faulty connections are causing the ROUTER (not the CABLE MODEM) to slow down. The reason I say this is when I connect from my PC, to the wall jack that goes all the way down to the basement (the 75' wiring) and directly connects to the cable modem, then I get the usual lightning speed result. So I am ssuming that whatever bad connections exist are NOT affecting the cable modem. Is that a correct assumption? Thanks again!

 

[bcastner]

I would think so, yes.

 

[opediggitty]

Yes that should be true since when you plug directly into the cable modem you are on a 10Mb link usually instead of 100Mb.

 

[jfguerra]

I'd like to again thank both of you for helping me pinpoint the problem.

For bcastner, I have one more question....I don't have an extra switch but I will get one (they're not too expensive). Here's my question. How will putting the switch between the router and the modem help if the router is still receiving a 100 mbps signal in the basement? Thanks!

 

[bcastner]

The reasons for autonegotiation failure are still somewhat mysterious. Some claim that it is an overvoltage on the interface introduced by some modem models. Some claim that it is just faulty firmware on the modem.

One of the functions that a switch performs without difficulty is taking 100 and connecting it to 10.

It also effectively buffers the overvoltage situation if that is what is the difficulty. The reason for the 50-75' roll of CAT 5 is both shielding and to lower through the resistance of the cable the voltage present at the router WAN port.

 

[jfguerra]

I got a switch (a Linksys Etherfast 5-Port Switch) and did a little experimentation:
1) First I connected it between tge cable modem and the router (all 3 pieces of equipment in the basement). I tried different combinations of ports (but always connecting to the WAN port on the Linksys BEFSR41 router) and I got nothing at all. the web pages didn't even come up this time.
2) On a whim, I connected the RJ45 plugs in the basement (that are fed from each of the 4 loactions in my home) directly to the switch and then connected the switch to the cable modem (in essence, I eliminated the router). Everything is working! The speed is fast, I get no web pages dropped, etc.

Am I missing something here??? What problems will I run into by doing this configuration?

Thanks again for ALL your help! You've made more progress on this problem than all the "tech support" I got from Linksys or Netgear (or my cable company for that matter).

 

[bcastner]

You would need to go modem to uplink port, and then regular port to linksys.

From your description it sounds as if in the past you were double NAT'ing, with modem acting as DHCP server and small router and the linksys taking a DHCP address and re-NATing it to the clients. It also strongly suspect an autonegotiation issue.

You have eliminated the double NAT, and provided a problem free 100 mbs. Full Duplex connection for all clients to the modem without negotiation mis-match.

If this is true, there is no reason not to leave it configured this way.

Please seem Tom's Hardsware Guide if you need to use the Linksys for expansion:

http://www4.tomshardware.com/network/20030716/index.html

 

[jfguerra]

Well, so far so good. With the Linksys Etherfast 5-Port Switch I am still running on my home network. We had a little problem earlier today when my wife tried accessing her corporate network through VPN but we figured out it was a problem on her corporate laptop (it's working fine now).

Bcastner...I did try the configuration you suggested (modem to uplink port on switch and then regular port to router) but it still didn't work.

I left the configuration of connecting all the RJ45 plugs in the basement directly into the switch and then connecting the uplink port of the switch to the cable modem. We're going to try it for all of next week. If it stays up, we keep it.

I'll still having the cable company come over to check their cable modem. As I look back at all the events that might of led to this problem, we had a lighting storm come through here a few weeks ago and it knocked out the original router I had installed a year ago and one of our LAN cards (despite being on surge protectors). So it's possible that it did something to the modem OR the wiring (I'm also having the wiring checked as well).

Thank you both again for all your help. We are up and running (so far)!

 

[bcastner]

As long as you think of the modem as a router, than the instructions I gave in the link to Tom's Hardware Guide would apply. To use the Linksys, you have to view it as a second router.

 

[toddbuckles]

I hate to jump in so late to this thread, but I have a little input that may help someone later. It seems to me the problem was actually PS-Xtalk of the short Cat5 cable. This is Power Sum Cross Talk, a phenomena created when you add the different types of x-talk inherent in even the best cables (I am assuming PS-ELFNEXT). In this case, it would seem the problem was the ELFEXT (Equal Level Far End Cross Talk) was very close (probably less than 1') from the NEXT (Near End Cross Talk), causing the equipment to drop packets at a rapid rate (most likely the modem, as effected by a static charge from the lightning storm, but could be the two routers). Why the switch worked, I am not sure, but it has less processing of packets than a router (but I still think it was the modem that was sensitive). Unless, when the switch was put in, a different cable was used, could have been a few feet longer, could have been better shielded...

Not being there, and the thread being several months old, this is just a guess, but it is a real problem that occurs often, maybe someone else will benefit.

Cheers,
TB