Help! School networking problem
 

Hi everyone,

I am new to this forum and am hoping you all can help me. I am the computer administrator at a small school. Last week I disassembled our computer lab which consists of:

12 Emachine computers
16 port switch
Linksys wireless router
Linksys 4 port switch
a router (Action-Tec)


I am the one who originally set all this (years ago) up but now can't get the computers to connect to the internet. I didn't move or unplug the router (it's in the office). On assembly, I set up all the computers, plugged each one into the switch with Cat5 cable, connected the 4 port switch and the wireless router to the switch. The wireless works fine but the wired computers won't connect. I did the usual correct order of powering up (router first, then switches then computers) The computers aren't getting ip addresses.

What am I doing wrong? I'm tired of wrestling with this.

Thanks in advance,

D

Re: Help!!
 

check the cables between the switches and the router, should be cross over, not straight trough

Re: Help!!
 

Thanks kpanchev

I'm sorry, but what is the difference between a cross-over and a "trough"?

Thanks, D

Re: Help!!
 

Crossover cables are designed for machine to machine direct connections. Straight/ patch ethernet cables are designed to be used to connect machines to network devices like a router or server etc.

Re: Help!!
 

Look at the colour of the wires at both ends, if the order is exactly the same, it is a straight trough, if pins 1 and 2 are placed to pins 3 and 6, then you have a cross over

Re: Help!!
 

Are your switch ports autosensing for the connection or do you require manual switching of the uplink port between a router and switch? Modern switches are generally autosensing, but older basic ones are not. The use of crossover cables on manual switches, or the correct setting of specific ports becomsin important.

Re: Help!!
 

Sorry to be the spelling police, but in instances where incorrect spelling is causing confusion, it's better to step up and correct the mistake ...

the word is THROUGH. A trough is something pigs eat out of.

The difference is between crossover cable and straight-through cable.

You use straight-through cable (also known as patch cable) for connecting a computer to a router, but if you're connecting two computers together (e.g. to share a network connection between them) then you would use a crossover cable. You would also use a crossover cable to connect two networking devices, such as the router/switch connection you are trying to make.

Newer networking devices can usually sense what sort of cable you have used and if you have used the 'wrong' one can adjust themselves to compensate, but that may or may not be the case here.

Whatever the exact fault is, if none of your computers are getting an IP address, then the fault has got to lie somewhere in the part of the network that all of them are connecting through. Try replacing the cable between the switch and the router first of all. It could be the wrong type or it could have been damaged when it was disconnected.

Re: Help!!
 

Wow, 3 o'clock in the morning does take it's due out of my spelling...

Re: Help!!
 

And what's your excuse at 11 o'clock in the morning? :p: (Don't tell me, it's because you're tired after staying up until 3am ... ) ;) :D

Re: Help!!
 

:sleeping: and a lame spell-checker...

Re: Help!!
 

This site is helpful for IT Techs in education: www.edugeek.net

Re: Help!!
 

hmmm, as the school PC network admin your going to have to be far more detailed than this

you say the wireless works fine, your giving the impression that the wireless PCs can get through to the web?, but i suspect you didnt mean that, rather, you can connect and see all the other (wireless)LAN connected PCs, but NOT get through to the web or the routers internal web pages!.

right, remember its all to do with the way it all connected like pipes or blocks, i hate using that example but it fits, keep it simple and report the IPs and auto/manual setting for your PCs sections (wired and wireless etc) 192.168.0.* and a mask of 255.255.255.0 for upto 254 devices in the LAN for now.


cable broadband in<===>"a router (Action-Tec)"port1<===>port1"16 port switch"

"16 port switch"port2<===>1-through-12-Emachine computers

port1"16 port switch"port16<===>"Linksys 4 port switch"port1<===>"Linksys wireless router"

something like that?, allowing for some all the Emachines to be wired in, but OC they can be on the wireless section instead of wired if you like.

start at the "action tec" router plug in 1 wired PC into the ethernet port, can can you get to the "action tec" internal webpages, check the settings, can you then get to the cable modem (or *DSL modem if thats what your using to get to the web OC) http://192.168.100.1/ or whatever the DSL page is.....

can that single PC get out to the web yes, move on...

plug each bit in the chain as you go, and run these basic checks from a directly wired PC at each switch, and the wireless internal web pages to check your settings.

if infact all the wireless PCs are getting through to the web then it seems the Linksys wireless router WAN port is talking to the master "a router (Action-Tec)" and negotiationg the right WAN/LAN IP mix....

if it is, then the problem might be at the a router (Action-Tec) or the "16 port switch" but you dont say if thats a dumb or a managed switch and so it has its own internal web pages as many 16P switchs are.

its unlikely the "Linksys 4 port switch" is managed but dont assume, know for sure.... then we might progress.

just think of each bit as a block, get the first incomeing Broadband to router block right, and plug in a PC to check, then move on to the others as you go, making sure the PC connected to each device is working and getting through to the web as expected, move along....

if that makes any sense to you?, do you now understand the crossover ethernet RJ45 cable thing?, and why you MIGHT need it?, read the manuals or post the EXACT model Nos so we can find them on line might be the next best thing.

do a quick drawing of how your are connecting it all up, including the IP ranges, and post it here on your next post, using that "Attach Files" below here were you type your reply window.

i always use this key to try and make it clearer, but a picture especially in your case is better OC so make one and post it.

<===> = straightthrough RJ45 cable
<=x=> =crossover RJ45 cable
<---> = wireless connection to and from a wireless router or access point.
---------- Post added at 11:42 ---------- Previous post was at 11:35 ----------

ps no excuses from me Chris OC ;), im just a bad speller and typeist and my Keyboard sticks as its old like me, thats why i keep going back in and editing 4 and 5 times but thats life take the help and Time i give freely or not as you chose ;)

Re: Help! School networking problem
 

For anyone wanting to spot if a cable is crossover or not...

Just hold the two ends side by side orientated the same way and look at the color coding. If it's identical then it's a Straight Through cable, if the colors are jumbled then it's a cross over cable.

On a router/switch/hub to router/switch/hub connection if you plug in the right cable then both link lights should light up. Also some routers/switches/hubs will have a little puch/toggle switch on one port (either the first or last) which will flick that one port over to cross-over or not. This could be marked uplink and will mean that you can use a through cable in replacement to a crossover cable. As already stated though most moderm routers/hubs/switches autosense and you can use a through cable on all ports

Re: Help! School networking problem
 

How much exactly has been changed? Have any of the computers has the OS re-installed for instance or is the hardware and software totally unchanged since disassembly?

Are any of the PCs able to see each other through the switch? What are they showing as IP address in ipconfig?

Re: Help! School networking problem
 

My gut feeling is that you have too much hardware. Is there any need to have that many switches and routers? What I often do is PCs > switch > one router (which handles the communication with the net (or other network) which seems to work. If you have a DC whack the DHCP on that, etc...

I suspect the problem is simply a lack of communication with the dhcp server.