no ip from 100ft cat5

stray~johnny · 02-07-2008, 10:37 AM

A customer of mine has a very large house. Originally he had his cable modem connected to a 5 port hub, and 5 lines running to all his computers around the house. He called me because only 3 of his computers get internet access the other 2 say "limited or no connectivity"

This was very easy to solve becuase I knew that shaw only gave 3 ips, so he needed a router. Hooked up a router and still only 3 computers get internet access. The two in the basement wont get an IP address off the 100ft network cable, but my laptop (G4 powerbook) will get an IP fine off the 100ft network cable and browse the internet. However the desktops WILL get an ip if I bring them up by the router and hook them up with 10ft network cable.

This is driving me crazy, I set him up with wireless temporarily.

johnwill · 02-07-2008, 04:04 PM

I'd bet that the pairs in the cable are not wired properly. If the cable is wired properly, there's no difference between six feet of cable and three hundred feet.

CAT5 Cable Wiring Diagram

HOW TO MAKE YOUR OWN CAT 5, TWISTED-PAIR NETWORK CABLES

stray~johnny · 02-08-2008, 11:07 AM

Thats what I would think as well, but I even purchased brand new cables and still nothing. Works fine on any 5 ft cat5 cable but the 100ft cables will not give the computer an IP address. I learned something during my networking course for troubleshooting networking problems and I seem to recall them saying that the longer the cable the less reliability you have. But they never said anything on how to make i work if its long. Is there some kind of amplifier or something? I just dont understand because I have wired houses that needed over 300ft of cat5 and they have never had a problem.

johnwill · 02-08-2008, 04:57 PM

Actually, I don't know what networking course you took, but they should update the curriculum.

A properly wired 100 foot CAT5 or better cable will have NO effect on the network connection. I've run CAT5e for more than 300 feet (yes, I know it's more than is in the spec), and the network performed flawlessly. Truthfully, I've never seen properly wired cables that don't exceed the specification ever cause an issue.

One thing that CAN affect a long cable run is ground differentials between the two connected machines. If the ground differential exceeds the common mode rejection capability of any of the NIC cards, then the connection will fail.

I still think it's a bad cable, or one that's wired incorrectly.

stray~johnny · 02-09-2008, 11:59 AM

Alright I will tripple check my connections again.

Thank You

02-07-2008, 10:37 AM	#1 (permalink)
stray~johnny Registered User Join Date: Dec 2007 Posts: 49 OS: winxp	no ip from 100ft cat5 A customer of mine has a very large house. Originally he had his cable modem connected to a 5 port hub, and 5 lines running to all his computers around the house. He called me because only 3 of his computers get internet access the other 2 say "limited or no connectivity" This was very easy to solve becuase I knew that shaw only gave 3 ips, so he needed a router. Hooked up a router and still only 3 computers get internet access. The two in the basement wont get an IP address off the 100ft network cable, but my laptop (G4 powerbook) will get an IP fine off the 100ft network cable and browse the internet. However the desktops WILL get an ip if I bring them up by the router and hook them up with 10ft network cable. This is driving me crazy, I set him up with wireless temporarily.

02-07-2008, 04:04 PM	#2 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 31,468 OS: XP-Pro, Vista, Linux Blog Entries: 1	Re: no ip from 100ft cat5 I'd bet that the pairs in the cable are not wired properly. If the cable is wired properly, there's no difference between six feet of cable and three hundred feet. CAT5 Cable Wiring Diagram HOW TO MAKE YOUR OWN CAT 5, TWISTED-PAIR NETWORK CABLES __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience

02-08-2008, 11:07 AM	#3 (permalink)
stray~johnny Registered User Join Date: Dec 2007 Posts: 49 OS: winxp	Re: no ip from 100ft cat5 Thats what I would think as well, but I even purchased brand new cables and still nothing. Works fine on any 5 ft cat5 cable but the 100ft cables will not give the computer an IP address. I learned something during my networking course for troubleshooting networking problems and I seem to recall them saying that the longer the cable the less reliability you have. But they never said anything on how to make i work if its long. Is there some kind of amplifier or something? I just dont understand because I have wired houses that needed over 300ft of cat5 and they have never had a problem.

02-08-2008, 04:57 PM	#4 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 31,468 OS: XP-Pro, Vista, Linux Blog Entries: 1	Re: no ip from 100ft cat5 Actually, I don't know what networking course you took, but they should update the curriculum. A properly wired 100 foot CAT5 or better cable will have NO effect on the network connection. I've run CAT5e for more than 300 feet (yes, I know it's more than is in the spec), and the network performed flawlessly. Truthfully, I've never seen properly wired cables that don't exceed the specification ever cause an issue. One thing that CAN affect a long cable run is ground differentials between the two connected machines. If the ground differential exceeds the common mode rejection capability of any of the NIC cards, then the connection will fail. I still think it's a bad cable, or one that's wired incorrectly. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience

02-09-2008, 11:59 AM	#5 (permalink)
stray~johnny Registered User Join Date: Dec 2007 Posts: 49 OS: winxp	Re: no ip from 100ft cat5 Alright I will tripple check my connections again. Thank You