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Connection works with a PC, not with a switch

Posted on 2012-08-16
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Last Modified: 2012-08-17
I'm setting up a computer lab at a facility whose network I do not manage. The IT guy on staff knows absolutely nothing about networking. The contractor they use is on vacation. From everything I've seen, all their hardware is Netgear, unmanaged, and the network is one big 22-bit subnet.

There's a drop in the lab. If I connect a PC to it, I get an address from DHCP. If I connect a switch, and then a PC to the switch, I get nothing.

The switch is a non-configured Cisco 2960. I didn't know the command off the top of my head to have the trunk interface request a DHCP address, and it was past quittin' time, so I left.

The only time I've seen this happen is when I had spanning-tree portfast on an access port, forgot, and put a little workgroup switch on the port.

Any thoughts on what I can try in the morning? I'm really hoping to only be there an hour or two.
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Question by:LSDIT
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Expert Comment

by:Norm Dickinson
ID: 38303001
Maybe a simple, unmanaged switch would work for this purpose if you are just trying to connect a couple of PCs to the network. Otherwise you will likely have to minimally configure the Cisco switch.

Here is a link to the configuration guide for the Cisco 2960 series in PDF form.

http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/12.2_40_se/configuration/guide/2960SCG.pdf
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Assisted Solution

by:Don Johnston
Don Johnston earned 1000 total points
ID: 38303039
Did you try a crossover cable?
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Author Comment

by:LSDIT
ID: 38303120
Crossover: No, but all ports on the 2960 are auto-mdix

Unmanaged switch: You're right, but I don't have one, and I'm five hours away from the office. I knew that this 2960 was already on-site and in my experience, a managed switch straight from the box behaves just like an unmanaged switch. What do you mean by "minimally configure?"
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by:Don Johnston
ID: 38303149
Auto is a four letter word. ;-)

Try a crossover cable.
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Expert Comment

by:Norm Dickinson
ID: 38303160
The switch has many features and perhaps it has already been used in a different environment with different settings. If that is the case you may need to reset it and follow the steps outlined in the Getting Started Guide found here:

http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/hardware/quick/guide_stack/All_languages/2960S_gsg_en.pdf 

To reset the switch:
Press and hold the Mode button. The switch LEDs begin blinking after about
3 seconds. Continue holding down the Mode button. The LEDs stop blinking after 7 more seconds, and then the switch reboots.
The switch now behaves like an unconfigured switch. You can enter the switch IP information by using Express Setup as described in the “Running Express Setup” section on page 4.

Press and hold the Mode button until all of the LEDs above the Mode button turn solid green. You might need to hold the button for 3 or more seconds.
Release the Mode button after all LEDs above the Mode button turn solid green. (The RPS LED remains off on some switch models.)
The switch is now in Express Setup mode.
Before proceeding to the next step, make sure that all LEDs above the Mode button are solid green.

Connect a Category 5 or 6 Ethernet cable to one of these locations:
• Any 10/100/1000 Ethernet downlink port
(such as port 1) on the switch front panel.
• The Ethernet management port on the
switch front panel.
Connect the other end of the cable to the Ethernet port on your PC.
Before proceeding to the next step, wait until the port LEDs on the switch and your PC or laptop are green (either solid or blinking). The green port LEDs mean a successful connection.

Enter the IP address 10.0.0.1 in a web browser and press Enter.
When prompted, enter the default password, cisco.
NoteThe switch ignores text in the username field.
The Express Setup window appears.

Enter this information in the Network Settings fields:
• In the Management Interface (VLAN ID) field, the default is 1.
NoteCisco recommends using the default VLAN value because during express setup, VLAN 1 is the only VLAN on the switch.
Enter a new VLAN ID only if you want to change the management interface through which you manage the switch. The VLAN ID range is 1 to 1001.
• In the IP Address field, enter the IP address of the switch.
• In the Subnet Mask field, click the drop-down arrow, and select a subnet mask.
• In the Default Gateway field, enter the IP address for the default gateway (router).
• Enter your password in the Switch Password field. The password can be from 1 to 25
alphanumeric characters, can start with a number, is case sensitive, allows embedded
spaces, but does not allow spaces at the beginning or end. In the Confirm Switch
Password field, enter your password again.
NoteYou must change the password from the default password, cisco.
Optional Fields
You can enter other administrative settings in the Express Setup window. For example, the optional administrative settings identify and synchronize the switch for enhanced management. The switch clock is automatically synchronized with the network clock by using NTP. You can manually set the system clock settings if the switch should have different time settings.
Click Submit to save your changes and to complete the initial setup.

The simplest way to manage the switch is by using the device manager in the switch memory. This web interface offers quick configuration and monitoring. You can access the device manager from anywhere in your network through a web browser.
1.Launch a web browser on your PC or workstation.
2.Enter the switch IP address in the web browser, and press Enter. The device manager page appears.
3.Use the device manager to perform basic switch configuration and monitoring. See the device manager online help for more information.
4.For more advanced configuration, download and run the Cisco Network Assistant, which is described in the next section.
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Author Comment

by:LSDIT
ID: 38303168
I'm sorry for not being clear. This is an unconfigured switch. It may have been configured for another location, but if so, I've previously wiped it. When opening a console session, you're prompted to run autoinstall. running-config shows that there is no configuration on any of the ports. (i.e., all at defaults)
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Expert Comment

by:Norm Dickinson
ID: 38303196
Sorry, I didn't read your post quite as close as I should have - you did mention that in the beginning.

You can assign IP information through the switch setup program, through a DHCP server, or manually. If you are using DHCP, do not respond to any of the questions in the setup program until the switch receives the dynamically assigned IP address and reads the configuration file.

Refer to the attached file for additional specifics of how to set it up for your needs.
2960SCG.pdf
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Author Comment

by:LSDIT
ID: 38303286
Yes, that is the 2960 guide.

But my primary question is: Why isn't the switch behaving as expected?

Maybe the switch is bad? Maybe my cable is bad? Maybe the switch on the other end won't allow another switch to connect? These are on my list of things to test in the morning. I was just hoping I could expand that list by a bit, in case these don't work.
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by:Norm Dickinson
ID: 38303321
Oh...well, that's a new way of putting the question. Yes, there are a lot of things that can cause a switch to misbehave, and not all of them are faulty hardware. Perhaps there is a setting on the network that requires the switch be authorized to obtain DHCP service and act like it is supposed to. Will you have access to the server or any other network equipment? You may need to add the MAC as a trusted device. Or you might have a bad port. A full factory reset - the ten second button push as opposed to the three second push - should get it to act like it was brand new, unless there is something wrong with it...
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Author Comment

by:LSDIT
ID: 38303352
I will not have access to any servers or networking hardware. And the guy who manages them is not available. And I live five hours away.

They can't be doing any sort of MAC authorization or filtering, because I was able to bring my laptop in, a brand new device, plug it in and connect just fine.

It seriously could be as simple as a bad cable. I brought up the console interface of the switch to verify that the config was blank, but that's pretty much the only troubleshooting step I got to. I had been drilling holes, running wires, zip-tying wires, and all the physical installation stuff all day. I was TIRED. I'm just hoping I can get everything running in the morning.
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Expert Comment

by:Norm Dickinson
ID: 38303380
The Cisco managed switch may need to be authorized on the DHCP server in order to provide DHCP to local clients. As it states on page 65 in the configuration guide,

You should configure the DHCP server with reserved leases that are bound to each switch by the switch hardware address.
If you want the switch to receive IP address information, you must configure the DHCP server with these lease options:
• IP address of the client (required)
• Subnet mask of the client (required)
• DNS server IP address (optional)
• Router IP address (default gateway address to be used by the switch) (required)

Is there any place on the way that you could pick up an inexpensive unmanaged switch to get them by until the contractor comes back?
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Author Comment

by:LSDIT
ID: 38303397
It's not just a dhcp problem though. I gave one machine a static address and it still wasn't working.
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Expert Comment

by:Norm Dickinson
ID: 38303425
Yeah, those managed Cisco switches are a little finicky when it comes to working automatically like that. I think you just have to go through the configuration steps from scratch and it will all run like it was meant to in the morning. Start with a hard factory reset. I don't share your experience of those devices working right out of the box on anything other than the simplest of networks, and even then not very often. They are often more trouble than they are worth - especially if it is the only one on the network. (They do have advantages in larger environments where everything is managed.)
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Author Comment

by:LSDIT
ID: 38303433
I suppose it's worth noting that I installed another 2960 in another office in this building a few weeks ago, and that one's working fine.
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Accepted Solution

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Norm Dickinson earned 1000 total points
ID: 38303450
That really does narrow it down to trying the factory reset option along with trying a different cable / different ports. It may be just a bad switch or cable after all. It does happen, just not very often with Cisco switches.
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Expert Comment

by:Don Johnston
ID: 38304533
Let's try a different approach:

When you connect the Cisco switch, what is the port status on the port which connects to the Netgear switch? Green, amber or off?

If it's green, what does the output of the following commands report (for the port)?

sh int status
sh int f0/x (where x is the port)
sh span
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Expert Comment

by:Norm Dickinson
ID: 38304553
I'm sorry - I really don't have that information readily available and don't want to leave you hanging on it, but my day is also about to get very busy and I know your issue is time sensitive. I also don't have a Cisco switch to test, either. Maybe you can check that on the other Cisco switch that is installed and working at that location? Or if not, can you post that as a new question to get a different expert to look at it? You don't have to mark this one answered if you don't feel it was, although your original question did pose itself as "Any thoughts?" and then sort of migrated into some specific technical details.
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by:Don Johnston
ID: 38304560
tqfdotus: I don't know who your post was directed to, up in the interest of clarity, my post/question was for the author (LSDIT).
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by:Norm Dickinson
ID: 38304574
Oh...my mistake - I didn't read the heading and assumed that your post was "to" me, and "from" the author. I will step out of this question - again - thanks for the clarification. (I wasn't aware there was anyone else on board since the crossover cable comment was posted.)
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Author Comment

by:LSDIT
ID: 38306452
Thank you to everyone. This issue was a result of my own end-of-the-day fatigue and carelessness. It was the cable. Swapped out the cable first thing this morning and all is well.
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Author Comment

by:LSDIT
ID: 38306751
I've requested that this question be closed as follows:

Accepted answer: 0 points for LSDIT's comment #a38306452

for the following reason:

Problem was my own fault.
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Expert Comment

by:Norm Dickinson
ID: 38306752
Well, the user did ask for ideas and maybe should spread some points around instead of awarding zero points. We tried, after all.
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Expert Comment

by:Don Johnston
ID: 38306758
I would agree.
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Expert Comment

by:Norm Dickinson
ID: 38306790
The cable was mentioned as a possible culprit in post http:#a38303450 as well as post http:#a38303039 so perhaps a 50/50 split would be in order?
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Author Comment

by:LSDIT
ID: 38306962
Of course!! I'm more than happy to award points, I wasn't really thinking of what accepting my own answer would signify.
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Expert Comment

by:Norm Dickinson
ID: 38307007
Thanks!
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