Cisco 2950 not recognizing pc/laptops.

[genurich]

All,
I work for a small MSO like Time Warner Cable / Cox Cable and Comcast... depending on who you have. We're removing our D-Links in the telco closet of an apartment building and replacing them with Cisco 2950T. Here's the problem:

My onsite engineer can connect with his laptop from a resident's apartment via a wall port going down to the 2950. When the resident attempts to connect, they all (any apt) get 'network cable unplugged' error. One resident then attached a router to the same wall port and attached the pc to the router--connected w/ no problem. The resident's laptop cannot connect. All along (in every apt) the engineer connects.

The error occurs with our field tech's laptop also. However, when the laptop is taken to the router, it connects just fine. When brought back to the apartment and connecting to the same switch port via a wall jack, there's no connection.

What we've done:
1. Manually configure 100/Full (speed/duplex)
2. I've researched changing the cable length field in the switch, but I think I'm reaching here. (cable length 150')
3. Fully reconfigured.
4. IOS is latest/greatest.

We have this set up in the development with D-Link (fricken d-link) and have no problem.

Please post a comment. Even if you can't resolve the issue, I sit alone behind an Inspiron 9400 and it gets lonely... Everything you smart gentlemen post helps.
I'm researching and will gladly post anything I find.

Thanks,
Rich

 

[AJ1982]

Silly thing but you mention plugging a router in, are you using CrossOver Cables here

You need a straight through to plug into a Switch from a PC

AJ

===

Fatman Superstar (Andrew James)

CCNA

 

[genurich]

It's not silly at all... But I'm using a straight cable. I checked that with the engineer onsite. The same cable connected at the router.

Thanks!

 

[nbowden]

Hi,

Are your residents NIC's definitely Ok with the 100/Full (speed/duplex) setting ?

It seems strange that your on-site eng can connect, but not the residents cannot.

Maybe try auto and see what happens ??

HTH

Nigel Bowden

http://www.bowden-software.com

 

[ADB100]

Have you got the cabling test results available? Can you test the cabling yourself? Is it over-length or wired incorrectly?
What NIC is in your engineers PC? If its a Gigabit 1000BaseT NIC then it is possible the cabling is wired incorrectly - i.e. crossed over. This is due to the 1000BaseT standard having built-in MDI/MDIX cross-over capability.

HTH

Andy

 

[genurich]

Switched to DLink and everyone connected right away... Not comforting whatsoever... We spent thousands on those switches. :-(... I can't manage the DLinks the way we need to... If anyone can think of anything, let me know.

I tested the cable, set all to auto. We're perplexed... Something in the water??

Rich

 

[kcbell]

I would try to make sure your cable is punched down correctly by using a cable tester to make sure it is straight from the apartment to the switch.

Dlink may have a auto correct to allow you to use straight cable but indeed you need a cross.

 

[bpinning]

Hey,

It could be something as simple as a problem with the NIC drivers on the Resident PC.

Check to make sure that they are the most recent.



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[mainstreetexpress]

Can you post the switch config

 

[genurich]

This is really good feedback! I'll check to see if the engineer's Inspiron 9400 onboard NIC is auto-correcting. If so, then I'll explore the auto-correct on the DLink. This could be the problem... The cabling issue. I would post the config... but it's so simplified, it wouldn't be the problem.

I don't know why it took me so long to find this forum...

Thanks!

 

[BuckWeet]

hah..

Sounds like to me you need to get teh cabling vendor onsite..

They wired one side for 568A standard, then the other for 568B..


Thats your problem..

Basically every connection is an X-over.

 

[vipergg]

I'm going to go on the assumption that your devices are not pulling addresses . On the cisco device on every "user" port add the command "switchport host" and see if that helps your situation. It is probably timing out waiting for spanning tree to run and then it doesn't pull an address .These are manageable switches and have many configurable options. You need to have spanning tree portfast turned on and the "switchport host" command will do that. Cisco 2950's are "not" auto mdix so you do have to have the correct cables to make sure they work.

 

[vipergg]

In looking at your original post do not leave the cisco 2950 ports hardcoded , most user pc's will be set as auto thus if you have the cisco end 100/full , the users end ewill default to 100/half because the cisco is not auto , this will cause a speed/duplex mismatch and cause all kinds of errors on the links and slow response . I think using the "switchport host" command might fix your problem , try it and post back here on results and or additional help.

 

[ADB100]

vipergg - I don't this is a portfast issue since he originally said:

all (any apt) get 'network cable unplugged' error.

I would probably take one of the users PC's and plug it directly into the 2950, bypassing the infrastructure cabling (probably easier taking the 2950 to the user?). This should prove whether the switch is at fault.
I agree though hard-coding the speed/duplex is not wise since unless the users have messed around with the NIC's settings they are likely to get duplex mismatches.

Andy

 

[vipergg]

Maybe , maybe not . Hopefully they are observant enough to see if they are getting a link light on the switch , if not then it is a layer 1 issue . In any case they should have portfast on all user ports...

 

[ADB100]

vipergg - I agree end user ports should be portfast enabled but I based on the original comments I think this is a Layer-1 issue. Let's see if the guy comes back with some more information.

Andy

 

[voltron1011]

I had a similiar situation before. The problem with the Linksys SOHO type switches is that not only are they auto sensing (speed/duplex), they also sense what kind of cable is plugged in (cross-over/straight-through) and adjust accordingly. So, you can plug a PC into the Switch with a cross-over cable and it will work. Or, you can plug Lynksys into another switch with a straight-thru and it will adjust accordinly. This is bad news for a network engineer trying to troubleshoot layer-1 issues. Especially when it comes time to introduce REAL switches into the network.

I suspect that all of the cables were wired incorrectly but weren't noticed because of the 'auto-sensing' ability of the Linksys. Get a cable tester in there to verify what kind of cables you're dealing with.

 

[voltron1011]

Sorry, I meant to say D-Link, not Linksys (they're all the same anyway)....

 

[genurich]

All... Buckweet was absolutely right... way to go! He wrote:



BuckWeet (IS/IT--Management)
16 Jul 06 12:53
hah..

Sounds like to me you need to get teh cabling vendor onsite..

They wired one side for 568A standard, then the other for 568B..


Thats your problem..

Basically every connection is an X-over.