Topic: Help vith physical network setup

[Kim Knudsen]

Hi,

I need some help with the physical setup of our network. The setup is as the following.

1 e-smith SME server 5.6u4 running server-gateway. 2 NIC's installed - 1 with our ADSL line in and the other put into a switch (not the uplink, as it didn't work, when I put the cable into there, even though I thought that I should do this?). In the same switch I have another PC and a connection to the uplink on a second switch from where there are both connections to PC's and a third switch uplink. We are running a network in about 20 apartments.
My problem is that only the PC connected to the same switch as the SME server can connect to the internet. The PC's connected via the second, third and so on switches can see the LAN but not connect to the internet.
The server is running DHCP and all PC's are getting assign the IP address, but they just can't connect to the internet.

What is wrong? It's driving me nuts as I think I've tried everything. It seems that the "internet"-connection doesn't go further than the 1st switch, but why?

Please help, as I have to get it working ASAP and in a hurry!

nimmer

[Kim Knudsen]

Just a little add-on:

We have a static IP-address from our ISP.

nimmer

[Boris]

Verify that there is link between the switches and that other computers DO get DHCP addresses. Make sure that light on uplink ports indicate connection. Check the type of cables used (straight through or crossover). Some small switches have two ports (Up-link and first or last regular port) mutualy excluded. You can use one or another but not both.
 In this setup computers in ALL appartments will have the same network range (192.168.0.x /255.255.255.0 I supose, or similar). Default gateway on all the computers will point to the LAN interface of your SME server as well as DNS.
If everything is correct and server itself can connect to the Internet and resolve URLs (try to ping www.goggle.com), it should work.

[Kim Knudsen]

Hi Boris,

The other computers DO get IP-addresses. All the cables used are straight-through and I'm aware about the shared uplink/port thing on my switches. And yes the default gateway and DNS points to the SME server.

I can connect to the internet with the server and with the PC connected to the same switch as the server. Although I can't ping from neither the server or the PC I can go to my browser and surf all the sites I want to.

Shouldn't the cable from the server to the first switch be connected to the uplink on the switch? If I do this, then there are no connection at all (no light in uplink or NIC on server), and I can't connect with the first PC. But if I just connect it to one of the regular ports, then the lights are on, and I can connect to the internet with the first PC, but not with the others on switch 2, 3, 4 and so on.

Do I need to use crossover cables from the servers NIC to the switch and from switch 1 to switch 2's uplink? Or shall I connect all the switches without using uplink ports at all?

nimmer

[Bill Pflaumer]

Kim,
From the internal NIC to the switch, do not use the uplink port. From switch A to B, go from the uplink port of SW A to a 'normal port of SW B and the uplink of SWB to normal port of SW C. Also, in reality, CAT 5 cables are straight thru but only pins 1,2,3, and 6 are used and must be made correctly for 100MB. See http://www.alatec.com/info/rj45.html. Are you truly getting  an IP address from the DHCP Server. Do an 'ipconfig /all' from each PC. Forget about the server for now and DHCP. Setup a PC on each switch, and give each a static IP address, say 192.168.10.1 /24 (/24 = 255.255.255.0) for PC on SWA, 192.168.10.2 /24 for PC on SWB and so on. Don't worry about DNS or Gateway setting for now. Verify pings between each PC on each switch and go from there. Use the 7 Layers of OSI  to troubleshoot (google search OSI layers if you don't know what I'm talking about) Lastly, are these new switches ? managed or unmanaged switches ?

Bill

[Dave Liquorice]

> The other computers DO get IP-addresses.

In the range and subnet that matches your SME server settings? Windows tries to be helpful and will put in default settings if it can't communicate.

> Although I can't ping from neither the server or the PC I can go to
> my browser and surf all the sites I want to.

Not sure I understand the first  part of that sentance.  Two negatives... B-)  Are you saying that you can't ping from one machine to anther on the same switch but you can browse the web? Most odd. Are you pinging by name or IP address?

> Do I need to use crossover cables from the servers NIC to the
> switch  and from switch 1 to switch 2's uplink?

Think of a crossover cable and an "uplink" port as the same thing. You connect an uplink port to a regular port on the upstream switch using a straight through cable.  Cascading switches can be fun I'd use this topograpghy:

Sw 1 reg > SME > Internet
     reg > Local PCs
     reg > up Sw 2 reg > Sw 2 PCs
     reg > up Sw 3 reg > Sw 3 PCs
     reg > up Sw 4 reg > Sw 4 PCs
     reg > etc

Where "up" is an uplink port and "reg" is a regular port all cables a straight through.

Cheers
Dave.

[Aaron]

Just a reminder that if you are using cheap (as in cost) switches like LinkSys etc that each are pre-configured with DHCP turned on so your workstations will certainly get an IP but not from the E-Smith as you desire but from the individual switch. I often forget this, for instance, when I update the firmware and it gets reset to factory defaults!

As was mentioned in other posts I think your best bet is to ensure you are indeed getting addresses from the e-smith and not from another source. ON the e-smith if your dump the /var/log/messages you should see the client DHCP request & server reply occur when you turn on a workstation cfg'd for DHCP IP. if you see no entries that would be a red flag. I would then suggest taking one PC from each of the swithces and manually cfg an IP just to nail down your network/cabling etc is indeed functional, then go back to getting the DHCP worked out.

Bottom line: I have a client with exactly your scenerio with the e-smith & cacsaded Linky hubs/switches and it works fine. Great actually.

As has been mentioned you will have to check your doc'n whetehr you need a x-over cable. Those days seem to be disappearing if you have relatively new equipment tho.

Aaron

[Dave Liquorice]

> Just a reminder that if you are using cheap (as in cost) switches like
>  LinkSys etc that each are pre-configured with DHCP turned on...

That and the abilty to upgrade the firmware doesn't sound like a cheap switch to me. They may be cheap *managed* switches but there are much cheaper *unmanaged* ones about that don't have such features.

Cheers
Dave.

[Kim Knudsen]

Thank you to all of you for your inputs.

My network now works. It were the uplink-thing that were wrong in my setup.

nimmer