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| Title: |
Working with Shared Folders and Printers in a Subnetted Environment |
| Applies to: |
Campus users who share resources such as files and printers over the network |
| Section: |
Network Services |
| Author: |
Kevin Gates |
| Last updated: |
23 March 2004 |
Introduction
One of the primary reasons for attaching computer systems to the campus LAN
is to allow sharing of information between computers. While many
methods of doing this exist, one particularly popular method on our campus has
been "peer-to-peer" (P2P) sharing of resources. P2P resource
sharing occurs when a computer on the network, typically a desktop system
located in someone's office, is configured to allow other users on the network
access to some or all of its resources. Most commonly these resources are
files and/or a shared printer. Recent versions of major operating systems,
including Microsoft Windows and Apple's MacOS, include features designed to
allow users to easily share these resources with a minimum of hassle on small
computer networks. However, changes to the configuration of our
campus LAN will potentially make it more difficult for users to use these
integrated OS file and print sharing features to exchange information within
their department and with other colleagues. The purpose of this document
is to discuss how these upcoming changes to our campus LAN will impact users who
user P2P resource sharing.
This document does not discuss the use of P2P file sharing programs such as
Kazaa, Grokster, Bearshare, Gnutella, Limewire, Morpheus, Napster, or Freewire.
The use of such programs on campus computers is highly discouraged as they have
a negative impact on our campus internet connection; they are the target of
numerous computer viruses and worms; and, when configured incorrectly, pose a
significant security risk to both user and institutional data.
Network Configuration Change
For reliability and security reasons, Network Services has undertaken a
project to virtually modify how network traffic travels on campus. Up until recently, our campus LAN was maintained as one single large entity
where every system was able to talk directly to every other system on the
network. In addition to being able to communicate directly with any other
system on the network, it was possible for a system to broadcast a single
message to every other system on the network. For example, when one computer needed to locate another it would broadcast a
message to every other machine on the network to find it. The changes to our network will divide it into a number
of smaller virtual networks, called subnets. Computers in each subnet will be able to
communicate directly with each other and traffic between computers in different
subnets will be routed between the subnets.
Our previous network design was not unlike a crowded gymnasium. Anyone in the
gym can easily locate and communicate with anyone else in the gym.
Announcement and general requests for information can also be made easily by
simply yelling out the information or question. With our updated network
design we are taking the people out of the gym and dividing them up among a
number of smaller classrooms. You can easily speak with anyone else in the
classroom and you can still make announcements and ask questions of the entire
classroom, but they are limited to the classroom you are in. It is still
possible to send information back and forth between classrooms but this is
typically limited to a single target at the destination (for example, placing a
telephone call to someone in the room).
Distribution of Subnets
The actual distribution of subnets will be based on the layout of the
network. Every Ethernet cable located on campus runs back to a wiring
closet, cabinet, or utility room, usually located on or near the same floor of
the building. Each of these wiring closets has one or more stacks of
networking equipment mounted into a network frame. Each network frame will
receive its own subnet. Users can determine their network frame by looking
at the network drop ID number printed on the wall plate in their office.
The first four characters identify your network frame. For example, if your
network wall plate says "ED531/12" then your network frame is ED53 and
your computer will be located in the same subnet as all other computer plugged
into wall plates starting with ED53.
Windows - File and Printer Sharing
Many campus users will be familiar with the "Network Neighbourhood"
or "My Network Places" icon from their desktop. Using these
icons, it was possible to graphically browse through a list of Windows based
computers located on the network and to access shared resources on these other
computers. When subnets are implemented, it will no longer be possible to
browse through the lists of all available computers. Here's why:
- Every Windows based computer has a unique name and they are organized into
workgroups.
- When each computer starts up in the morning it broadcasts a message
announcing its name and workgroup. This is much like someone standing
up in our gymnasium and yelling, "Hi! My name is Jim and I work for
Computing Services."
- The computers located on the network listen to the broadcasts and keep a
list of workgroups and which computers are in the workgroups. This is something
of a simplification of what really happens under the hood of your computer, but
it is accurate enough for our discussion.
- With our analogy, when we are all in the gymnasium, it is possible for us
to listen to every person's announcement and get a complete list of everyone
and what group they are in.
- When we switch over to our classrooms, the walls will keep the
announcements from traveling outside our our room. So we will only
know about the people and groups located in our own room.
- With our new network design, the range of broadcasted messages will be limited
to the subnet that they originate in. As such, the list of
workgroups and computers will only contain those systems attached to the
same network frame as you are currently located in.
For example: Suppose that computers A and B are located on the 1st
floor of the Education building and computers C and D are located on the 5th
floor of the Education building and that they all belong to the "Smarties"
workgroup. When computer A browses the network neighbourhood it will see
itself and computer B. When computer C browses the network neighbourhood
it will see itself and computer D. Computer B will not automatically be
able to browse to computer C or D etc, etc.
However, there is some good news. Even if you can't browse to a
computer on the network using network neighbourhood, you can still access it.
All you need to know is the name of the computer you are trying to access.
Users who have previously placed an icon on their desktop or who have mapped a
network drive to a shared Windows computer will still be able to use those icons
or mapped drives. Users wishing to use resources on a computer they have
not previously accessed can do so as follows:
- Click Start
- Click Run
- In the run dialog box type "\\computername"
(without the quotes and with the real name of the target system instead of
the word computername). ex: \\softdist
- click OK.
- If you have spelled the name of the computer correctly and if you have
security access to the shared resource, a window with a list of the shared
resources on that computer will appear.
- You can connect directly to a specific resource on a computer by typing
"\\computername\resourcename"
in the run dialog box. Again, it is without the quotes, and the real
computer and resource names should be substituted. ex: \\softdist\pub
- You can create create an icon on your desktop that leads directly to the
resource. Start by using the normal procedure to create a shortcut and
then when prompted for a location, enter the "\\computername\resourcename"
name. Finish off the shortcut as you normally would. Be warned
though that desktop shortcuts to network resources will slow down your
computer at boot time.
If you are sharing files with a colleague, you may need to tell them your computer name
so that they can connect to it. If you do not know your computer name, you can determine
it as follows:
- Under Windows 98:
- Click START -> Click Settings -> Click Control Panel
- When the control panel appears, double click the network icon.
- A network window will appear. Click on the Identification tab.
- The identification properties of your computer will appear and your computer name will be listed.
- Click cancel to close the Network window and close the control panel.
- Under Windows XP
- Click Start -> Click Run.
- In the run dialog box, type msinfo32 and click ok.
- A system information window will appear. On the right hand side of the window, look for your system name.
- Once you have located your system name, close the System Information window.
Printing to Network Attached Printers
Some systems on campus may be configured to print directly to a network
attached laser printer without the use of an intermediary server. Quite
often the IP address of the printer is hard coded into the computer system to
allow communication. However, under the new network design, the IP
addresses of printers will likely change. Additionally, under the new
system, the addresses are allocated dynamically and it is possible that even
after the new design is implemented there are circumstances that could cause the
printer address to change again. To minimize support problems, it would be
advantageous to configure computer systems to print to the domain name of the
printer rather than the IP address. This can be done using the integrated
printing software that is included with Windows XP. This cannot be done
using older versions of the HP Jetdirect software that is used on many Windows
98 systems. Possible solutions to this issue include loading updated
software that will accept domain names or allocating a special static IP address
for the printer. Allocating the static IP address may also be necessary
for printing from Apple systems running older versions of MacOS.
Under Windows XP, the procedure to determine a system or printer's domain name
is straightforward if you have the IP address.
- Click Start -> Click Run
- In the Run dialog box type CMD and click OK.
- A command prompt window will appear.
- In the command prompt window type nslookup XXX.XXX.XXX.XXX and press enter.
You will need to substitute the correct IP address of the printer instead of the XXX.XXX.XXX.XXX.
ex: nslookup 142.3.154.2
- If a domain name exists for the IP address it will be displayed on your screen.
- Type exit to close the command prompt window.
For assistance in determining domain names if you do not have Windows XP, please
contact your departmental technician or the Computing Services IT Support Centre @ 4685.
MacOS
Apple users who configure their computer systems to use TCP/IP for accessing
shared network resources should still be functional after the new network design
is implemented. In particular, MacOS X borrows heavily from the Unix world
for its core functionality and should have little trouble with the
transition. Users should be aware that when the switchover occurs, many IP
addresses will change. Where possible, it would be advantageous to use the
domain name of the target system (ex: softdist.cc.uregina.ca) instead of the IP
address (142.3.154.2) when setting up shares. With MacOS, using Appletalk
will not allow you to access shares outside of your own network frame, so be
sure to enable the sharing via TCP/IP.
For additional help with Apple products please contact your departmental
technician or the IT Support Centre @4685.
Troubleshooting
If you are having difficulty using the file and print sharing features that are
integrated with your operating system, please contact your departmental computer
technician or the Computing Services IT Support Centre @ 4685.
Conclusion
Anticipated file and print sharing difficulties due to the subnetting of the
campus LAN are described.
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