Network and Wireless

Network Malfunctions

Broken Network Connection

Make sure the network cable is plugged into the back of the computer. If it is connected, see if the failure extends to more than one remote host. Report your findings to the systems operator.

MAC Addresses

Introduction

A MAC or Media Access Control address is a unique identifier that is used in networking. It is also sometimes called the "Physical Address". Currently the Ethernet specification uses a MAC convention scheme called "MAC-48" which has 2^48 possible unique identifiers for each device on a network. IEEE expects MAC-48 space to be exhausted around the year 2100 at which time a newer specification such as EUI-64 will have to be used. Every network interface card (NIC) has a MAC address "burned in" from the manufacturer. This can be overwritten by software using a "locally administered address". MAC addresses are formatted as a sequence of 6 hexadecimal pairs, e.g. 00:AA:22:33:44:FF

How they are Useful

Besides their purpose in networking, MAC addresses can also be used for access control, for both DHCP servers and Wireless Access Points. For the Keller Hall Wireless network we require you to register your "burned in" MAC address that came with your wireless network card in order to restrict wireless access to only staff, grad students, and undergrads enrolled in CSE Labs courses.

How to find your MAC Address

Windows 2000/2003/XP

1. Go to the Start Menu
2. Click on Run
3. Type in "cmd" and hit enter
4. In the command window that comes up type "ipconfig /all"
5. Your MAC/Physical address should be printed for all of your network cards. Look for the one under something like "Wireless Network Adapter 1" or "Broadcom Wireless NIC" etc.

Macintosh

1. Go to Applications -> Utilities.
2. Open Network Utility.
3. Select the "Info" tab.
4. Select the "Ethernet Interface (en1)" from the pull down menu to get to your wireless info. (you could select "en0" for your wired info or "fw0" for the info about your firewire connection)
5. Your MAC address is the string labeled "Hardware Address".

Linux/Unix

You can use the "ifconfig" or "ifconfig -a" command to find your hardware address. In Linux this is printed by default for each real interface and is called "HWaddr". The output of ifconfig varies from distribution to distribution. Consult the man pages for ifconfig to find out how to locate the MAC address.

Wireless Access

Wireless access in Keller Hall is now provided by the Office of Information Technology (OIT) at the University of Minnesota. For more information on getting connected, please visit OIT's Wireless Setup Guide.

Connecting Your Laptop to the CS&E Network

If you want to use your laptop on the CS&E network, please submit the CS&E Wired Access Form. You will need to login using your CS&E Unix username and password. If this request is for a visitor, a faculty member must submit the form on the visitor’s behalf.

Once we have granted your laptop access, you will receive a message from operator [at] cs.umn.edu . Please read over Account Policies before accessing the network.

Personal Desktop Computers

We do not allow personal desktop machines to be connected to the network. There are a couple of reason for this.

1. It interferes with our inventory system.
   Once a year we go through every room in the building and update our inventory database. When a systems staff member enters a room they check the S/N, make, and model of each computer or printer in the room. If it is not listed in our inventory system, we add it. If personally owned PCs are in the room they get added and that causes a variety of problems down the line. We do not inventory laptops, so laptops do not cause a problem.
2. More importantly, we simply do not have the human resources to handle our current tasks and also support personally owned PCs.