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SHEFFIELD HALLAM UNIVERSITY.
SCHOOL OF COMPUTING AND MANAGEMENT SCIENCES.
Experiment 11:
Configuration of a remote LAN connection
via ISDN
COMPUTER NETWORK EXPERIMENT
TITLE
Configuration of a remote LAN connection
via ISDN
AIM
To understand the requirements for remote LAN connections. To understand the technologies behind
network bridgeing and ISDN.
OBJECTIVES
1. Understand the basic concepts of ISDN
2. Understand the basic concepts of Bridging
3. Applythis knowledge to make a remote LAN connection.
PRE-REQUISITES
 You should be familiar with Microsoft Windows 95
 You should have read the notes in the Appendix.
EQUIPMENT REQUIRED




2 x 3COM Office Connect 530s
2 x ISDN points
1 Hub port
A management console for the 3COM equipment
ESSENTIAL READING
http://support.3com.com/infodeli/tools/remote/ocremote/brouters/ocr5ug/index.htm
Office Connec t 530 User Guide, Sections; Example of typical ISDN Network Applications, and
Bridging and Routing
Business Data Communications and Networking J. Fitzgerald, & A. Dennis, Wiley 1996.
Routing 220-222, 336,337, ISDN pp308, 309
FURTHER READING
http://www.timm.demon.co.uk/
UK ISDN Guide
http://www.ziplink.net/~ralphb/ISDN/
ISDN Tutorial
http://www.isocws.isoc.org/course/t4/introroute/index.htm ISOC IP Routing
http://www.3com.com/products/dsheets/400318.html 3COM OfficeConnect® Remote Access
Routers
Mark Jacobi
Updated Dec '99
REQUIREMENTS
 You are required to read the attached notes and necessary preparation before attempting the
practical exercise
 You should provide solutions to the questions posed throughout the exercise
 You should document your research and procedures
QUESTIONS
1. What is an IP mask?
2. Why is the ISDN1 LED lit almost permanently even when you are not sending
messages using IP?
3. Why does the ISDN2 LED only occasionally light up?
4. How would you reduce the amount of time that the ISDN line is in use (and
hence reduce the ISDN billing cost)?
5. How would you improve the security for the local and remote sites?
SCENARIO
The scenario for this experiment is that an organisation has a LAN situated at its local
office. The organisation has a number of staff operating at remote sites that need to
connect to the local office. All of these remote sites have ISDN connections, some
have their own LAN's but this particular one has just a single PC that needs
connecting.
FIGURE 1. Remote access configuration
LAN
Local
Office
Remote
Site
Hub
ISDN Bridge
ISDN
ISDN Bridge
ISDN
ISDN Router
Other
Sites
ISDN
Mark Jacobi
Updated Dec '99
INSTALLING AND TESTING THE ISDN BRIDGE
The ISDN Bridges that we will be using are 3COM Office Connect Remote 530s.
These can be configured as either Bridges or Routers. You must read the essential
reading references to ensure that you understand the reasons for the configuration
used.1
STAGE 1: CONNECTING THE EQUIPMENT
3C530-ONE
COM port on
managemen
t terminal
ISDN
LAN Hub
/Switch
3C530-TWO
ISDN
PC
Network
Card
The two bridges are lablelled 3C530-ONE and 3C530-TWO. Bridge ONE will be
connected to the existing LAN via a hub/switch and bridge TWO will be connected to
the remote PC. Both bridges use 10BaseT connectors for connecting to the network.
The bridges are configured and monitored using a terminal emulator application
installed on the management terminal PC. Windows 95 and NT have a tool called
Hyperteminal installed which is suitable. A terminal called 3COM.ht has already been
setup, but if this cannot be found create a new terminal setting the baud rate to 9600, 8
data bits, 1 stop bit, no parity.
1. Connect the bridges to the ISDN lines using the ISDN cables provided, note the
ISDN numbers on the ISDN boxes.
2. Connect bridge ONE to the hub/switch using a free port and bridge TWO to the
network card on the remote PC. Ensure that the correct socckets on the Bridges are
used.
3. Ensure that the MDI/MDIX Switch on the rear of the bridges is in the IN position
on the bridge ONE and OUT on bridge TWO. This implements the 10BASET
crossover that is required.
4. Connect the serial port on bridge ONE to the COM 2 port on the management
terminal PC. You will be configuring this bridge first.
1
http://support.3com.com/infodeli/tools/remote/ocremote/brouters/ocr5ug/index.htm
Office Connec t 530 User Guide, Sections; Example of typical ISDN Network Applications, and
Bridging and Routing
Mark Jacobi
Updated Dec '99
The Bridges should now have the PWR. LINK, and ISDN OK lights illuminated
indicating that power is connected, the LAN link is up and the ISDN connection is
live.
5. Startup the Manager terminal PC and boot into Windows 95
6. Select 3Com.ht from the Program - Accessories-Hyperterminals menu on the
START button.
7. Press the RETURN key and you will be prompted to enter a password. Type
PASSWORD in capitals.
You have now started the Management System and can begin configuring the bridges.
STAGE 2: SETTING UP AN IP BRIDGE
Before configuring the bridge you must return the bridge to its factory default settings.
You should already be at the Main menu on the Management System.
Type CO STD and answer Y to confirm. The unit will restart and run through its
self test procedure.
2. You will then have to re-type the password, PASSWORD, to return to the Main
menu.
1.
The bridges have a Quick Configuration procedure for setting up basic connections.
We will use these for simplicity. Each unit must also be allocated an IP address
belonging to the same IP network as the LAN to which we are connecting.
From the Main menu type QC to access the Quick Configuration menu. Type NA
to setup the unit name and IP address.
4. Type 3C530-ONE for the Unit Name.
5. Type 143.52.57.60 for the unit's IP address.
6. Type 255.255.255.0 for the Unit LAN IP mask.
7. Leave the Network Type set at United Kingdom and the SPIDs, and Directory
numbers blank, type ^E and then type SAVE to save these details.
To check that the ISDN connection is OK perform a loopback test:
8. Type CO PO to monitor the status of the units ports.
9. Call the units own ISDN number by typing CALL 2761921.
3.
If it works the ISDN1 and ISDN2 port's NAME fields will show "LOOPBACK!" and
STAT "UP".
Type CANC to cancel the call, and QC to return to the Quick Configuration menu.
You can now setup the bridge to connet to an IP host on the same network.
11. Type IPB to setup the bridging parameters.
12. Type the ISDN number of the remote bridge, 2761468
13. leave the Call Type set at 64K unrestricted and IP address at the remote host set at
Default.
14. Type ^E to submit. The unit will say 'Wait while learning'. It is now connecting to
the other bridge and will create a table a learned devices.
15. Type SAVE . To view the address table type CO BR AD.
16. Type ^G to return to the main menu and type QUIT
10.
Mark Jacobi
Updated Dec '99
You must now setup the other Bridge.
Move the manager terminal serial lead from bridge ONE to TWO.
Press RETURN and enter the password PASSWORD
Type CO STD and answer Y to confirm. The unit will restart and run through its
self test procedure.
20. You will then have to re-type the password, PASSWORD, to return to the Main
menu.
21. From the Main menu type QC to access the Quick Configuration menu. Type NA
to setup the unit name and IP address.
22. Type 3C530-TWO for the Unit Name.
23. Type 143.52.57.61 for the unit's IP address.
24. Type 255.255.255.0 for the Unit LAN IP mask.
25. Leave the Network Type set at United Kingdom and the SPIDs blank, type ^E and
then type SAVE to save these details.
17.
18.
19.
To check that the ISDN connection is OK perform a loopback test:
26. Type CO PO to monitor the status of the units ports.
27. Call the units own ISDN number by typing CALL 2761468
If it works the ISDN1 and ISDN2 port's NAME fielsd will show "LOOPBACK!" and
STAT "UP".
28.
Type CANC to cancel the call, and QC to return to the Quick Configuration menu.
You can now setup the bridge to connect to an IP host on the same network.
Type IPB to setup the bridging parameters.
Type the ISDN number of the remote bridge, 2761921
leave the Call Type set at 64K unrestricted and IP address at the remote host set at
Default.
32. Type ^E to submit. The unit will say 'Wait while learning'. It is now connecting to
the other bridge and will create a table a learned devices. To view this table type
CO BR AD. You will be able to see addresses of all the devices that can be seen on
the LAN
29.
30.
31.
This quick configuration turns IP learning on and will build an Autocall entry after it
has learned the ARP/IP entries. You can view the table of learned entries by typing
CO IS AUTO. Once both units have learned the each other's ARP/IP entries an
autocall will be placed based on traffic. When a workstation sends out ARP/IP packets
the autocall entry will bring up the ISDN connection. If no data is being passed (based
on the IDLE timeout set in the unit) the ISDN line will be dropped. When the unit
detects data that needs to be passed the ISDN line will be re-established.
33.
Type ^G to return to the main menu.
Mark Jacobi
Updated Dec '99
You have now setup the units for bridging and have connected the remote PC to the
network. Obviously the local PC must support TCP/IP and have its own IP address, in
this case it is 143.52.57.36
STAGE 3: TESTING THE IP CONNECTION
Ensure that the remote PC has been correctly configured for TCP/IP networking. The
network lab normally allocates IP addresses dynamically using the DHCP protocol.:
1.
2.
3.
4.
5.
6.
Boot the remote PC into Windows 95, do not try to login to netware
Select Start - Settings - Control Panel - Network to open the Network Setting
window, and select the Protocols tab.
Highlight TCP/IP and select Properties.
Set the IP address for the PC. This can be found on a lable on the top of the tower
case.
Check the IP address is set to 143.52.57.125 and the subnet mask should be
255.255.255.0, the default gateway should be 143.52.57.2 select ok.
Select the DNS tab an ensure the following settings are used (the computer name
is also on the case label):
Host cms-2413-25
Domain ac.uk
DNS Search addresses 143.52.2.18 , 143.52.28.10
Reboot the machine into Windows 95 if you have made changes. You can also
now login to the network using the netlab login id.
The simplest way to test an IP connection is to use the PING command. This send a
number of IP packets and gives the length of time that the destination took to respond.
7.
8.
Open up the MS-DOS command prompt, Programs-Command Prompt
Type ping 143.52.57.2 to send IP packets to the networks lab gateway router.
There should be a reply from 143.52.57.2. If there is no response and the reply times
out check the link firstly betwwen the remote PC and Bridge TWO by typeing ping
143.52.57.61 and then the ISDN connection by typeing ping 143.52.57.60. This
should identify where the problem is.
9. Start Netscape Communicator and try some surfing to ensure that TCP/IP is
working. You will need to login to Netware using the id netlab with no password.
10. On the Management Terminal type CO PO to monitor the ports while surfing or
downloading. You can also monitor the ports by watching the LEDs on the Bridge
front panel.
11. Type ST IS to monitor the ISDN stats.
You could also try logging in to the netware network and monitor the stats.
STAGE 4: FINISHING OFF
When you have completed your investigations you must delete all entries made in the
Management system by returning the unit to factory defaults. This will ensure that the
Mark Jacobi
Updated Dec '99
ISDN line is not used unneccessarily and that the next group can start the exercise
from default settings.
1. Connect the Management system lead to Bridge ONE, enter the password then
type CO STD and confirm your request with Y. The Bridge will reboot.
2. Connect the Management system lead to Bridge TWO, enter the password then
type CO STD and confirm your request with Y. The Bridge will reboot.
3. Disconnect the cables from the bridge but leave attached at the other end.
4. On the remote PC, delete the host IP address from the TCP/IP settings window.
Mark Jacobi
Updated Dec '99
APPENDIX 1
NOTES: An introduction
to Bridging and ISDN.
Extract from Office Connect Remote User Guide, 3COM.
In the modern business environment sharing information is crucial. Until now only
large businesses could afford the high speed connections between
offices to gain the networking advantage.
The OfficeConnect Remote is designed to connect a LAN (Local Area Network) at
one location with a number of other LANs at remote locations. The LAN could
comprise any number of PCs, servers or other computing equipment, which in an
office or small business environment are typically linked together using a centrally
located Office Connect hub. In order to interconnect the hubs in different locations,
the OfficeConnect Remote unit transmits information over a WAN (Wide Area
Network) service provided by telephone carrier organizations. The most modern and
efficient of these WAN services includes ISDN (Integrated Services Digital Network).
This provides a high speed dialup facility to allow your OfficeConnect Remote to
automatically and quickly dial remote offices, transmit your data between remote PCs
just as speedily and then disconnect the call. You incur minimum ISDN telephone
charges as calls are made only when needed. This is known as Dial on Demand.
ISDN
ISDN, (Integrated Services Digital Network), is a system of digital phone connections
which has been available for over a decade. This system allows data to be transmitted
simultaneously across the world using end-to-end digital connectivity.
With ISDN, voice and data are carried by bearer channels (B channels) occupying a
bandwidth of 64 kbps. A data channel (D channel) handles signaling at 16 kbps or 64
kbps, depending on the service type.
There are two basic types of ISDN service: Basic Rate Interface (known as ISDN2 in
the UK) and Primary Rate Interface (ISDN30).
BRI consists of two 64 kbps B channels and one 16 kbps D channel for a total of 144
kbps. This basic service is intended to meet the needs of most individual users. PRI is
intended for users with greater capacity requirements. Typically the channel structure
is 30 B channels plus one 64 kbps D channel for a total of 1984 kbps.
BRI is the connection type used in the labs. It is possible to operate 2 separate pieces
of equipment accessed by 2 separate numbers, or to have the 2 channels aggregate to
provide a single, higher data rate connection.
Bridging
Bridges and routers are used to connect networks together. The cost of connecting
networks together is generally proportional to the distance over which the network
extends and the amount of bandwidth required. Large amounts of bandwidth can be
provided easily within a LAN by connecting different segments together with a local
bridge. However, it becomes impractical and expensive to extend this bandwidth over
larger distances, and it is, therefore, usual to interconnect local high speed networks
using bridges or routers connecting over slower speed terrestrial and satellite links.
Mark Jacobi
Updated Dec '99
A bridge connects one or more LANs together. It examines each data frame received
at a LAN port and forwards any frames that it assumes are for a destination device not
connected to that LAN port. The bridge is able to do this by learning which devices
are connected to each LAN port. A router learns much more about the networks
connected to it and is able to be much more selective about the data it passes on to
other networks and to which networks it transmits. By default routers reject or filter
data unless it matches predefined attributes (for example specific protocols or
destination network addresses). In large interconnected networks a router selects the
best route for data to travel.
Mark Jacobi
Updated Dec '99