Does a 'link' LED on a switch mean anything?

oscarBravo

I installed a WAP in the attic (seemed like a good idea at the time). The signal wasn't very reliable in the kitchen, so as an experiment I've moved the WAP to the sitting room. Now it doesn't work at all.

When I plug it into the length of Cat5 I installed in the room last year, its Link LED lights. I've checked the switch and it shows an active link also. Sadly, I can't see it on the network. Its IP is set to 192.168.0.3, and it's not answering pings.

I thought maybe it "forgot" its IP address, so I fired up the access point software on the missus' PC (it's the only one still running windows), and gave it the MAC address: still can't see it.

I would have thought that a Link LED on the switch was enough to guarantee a connection - is it possible that I have a faulty cable, but that it still allows a link to appear active?

The thought of a faulty cable is pretty much the worst case scenario: replacing it means pulling a new one through a cavity wall! Doable, but horrible.

Serbian

Could it possibly be on a different subnet? Try subnet 255.255.255.0.

Other than that, I'm not sure what it could be. Would it be possible to move the machine closer to the switch and test a new cable there? Would save you having to do all the re-wiring to find that the cable wasn't the problem.

Might also be a good idea to invest in a set of cable testers. They're not too expensive as far as I know, and useful for testing problems with ethernet cables.

Capt'n Midnight

Is the plasterboard in your walls foil lined ? - if so then you will get a better signal from the attic than form the next room. Also make sure the antennas are horizontal rather than vertical if you put it in the attic.

Maybe it's been reset to it's default IP - you could also try resetting it..

If the cable is faulty remember only two pairs are needed - you might be able to cross wire at each end ...
(if the link lights come on at BOTH ends then probably ok though)

Try a broadcast
[php]ping 192.168.0.255
arp -a[/php]

bricks

It only takes one of pairs to connect then you get a link light.
So maybe there is a problem with the cable.
Check your cable.

spongebob

if the cable is staright thru then where is the crossover? the switch and the WAP need a crossover somewhere, they are both hubs aren't they ? .

Usually you use a specific UPLINK port on the switch or a normal port and press small button beside it , port 8 maybe ?

if the CABLE is the crossover then you plug into a normal port on the switch not the specific uplink one.

M

sirlinux

I would suggest reseting the WAP to default settings, the link light will come on even if it isnt working to well.

oscarBravo

Interesting points all.

I don't think this is an IP issue. I loaded up the AP software to check specifically for that, and it couldn't find it. I'm pretty sure it scans the network for the MAC address, not the IP. I tried a broadcast ping, and it's not answering.

Cap'n: house is concrete block, not plasterboard. Such plasterboard as there is is not foil lined. The walls are very thick in places: two 4" blocks plus insulation. Both the WAP and the switch show a link light.

Muck, the WAP doesn't act like a switch. Even if it did, the switch has autosense on all ports, so it doesn't matter. It has worked up until now with a straight cable.

There's still a bit of slack in the cable, so I'll re-terminate it: maybe I just made a hooja of crimping the plug on, I did it in a bit of a hurry.

Thanks for the input.

an_taoiseach

Oscar,

Cable should be straight through

Pins 1,2,3 & 6 ( orange pair pins 1&2, green pair pins 3&6)

Do you have a link light at the access point end ?

If so see that it is ON as well as the one at the switch end

You have set up the AP on subnet 192.168.0.X with a class C mask ?

If so verify that your PC is set for the same subnet ( but different IP address )

Can you verify the operation of your NIC ? can you ping some other IP device from it ?

WiFi operates in the same general band as DECT phones, video senders ( & leaky microwave ovens ) so these thing can cause problems but at the stage you are at you have a 'wired' rather than 'wireless' problem


An T

andrew163

...oh THAT problem.... *shudders at memories of certain lan party*

did you try a different protocol to see if you can get any data to transfer over it?
I tried using file sharing over IPX when NOTHING would work over TCP/IP.... and it worked. This would tell you if the problem is a physical (eg dead cable/NIC/switch/etc...) or software (protocol stuff) one.

hth

oscarBravo

I tried the AP plugged back into the other switch (I've two switches connected together at opposite ends of the house) and it works perfectly, so it and the card are fine.

It's funny, not only was there a link light on both the AP and the switch, but the 100M light was on on the switch also. That's what had me fairly sure the cable was OK.

I'll have to crawl into the attic with a short patch cable and the AP, and see if the laptop works right beside it. If so, it's definitely a cable issue - could still be a bad termination though, I haven't had a chance to re-terminate yet. All come to all, I'll pull a new cable - at least it isn't plastered into the wall, and I had the foresight to leave a pull-string in place!

an_taoiseach

It's funny, not only was there a link light on both the AP and the switch, but the 100M light was on on the switch also

In that case the Ethernet port on the AP is 10/100 ?

An T

Capt'n Midnight

Can you detect the AP with Netstumbler or the client cards utility - if not then the unit may be sick or upset...

If you can detect the AP Does it have NAT or WEP or MAC filtering ?
If none of the above then it will just pass packets to the RJ45 port - regardless of it's IP settings. At that stage you should be able to sniff packets.

Had a network card at work fail - it can sniff packets but won't transmitt them ! - ie. the light is on but no one's home (or at least the aren't answering the door)