Analyzing ISDN Signalling Messages
University of Guelph Humber
Broadband Communications DCCT 4020
Analysing ISDN Signalling Messages
Introduction:-
Integrated Services Digital Network (ISDN) is comprised of digital telephony and data-transport services offered by regional telephone carriers. ISDN involves the digitization of the telephone network, which permits voice, data, text, graphics, music, video, and other source material to be transmitted over existing telephone wires. The emergence of ISDN represents an effort to standardize subscriber services, user/network interfaces, and network and internet work capabilities. ISDN applications include high-speed image applications (such as Group IV facsimile), additional telephone lines in homes to serve the telecommuting industry, high-speed file transfer, and video conferencing. Voice service is also an application for ISDN
ISDN uses LAPD (Link Access procedure-D) at layer 2 that are very similar to HDLC.
ISDN uses SS7 call set-up and termination procedures. The SS7 is a powerful out of band signalling protocol that is extensively used in wireless telecommunication Networks.
Objective:-
1. Build, set-up and configure an end- to end ISDN Network for voice and data communications over an ISDN U interface using an ISDN Simulator
2. Study and analyse ISDN Layer 2 and Layer 3 Signalling messages
3. Study ISDN call set-up and call termination procedure.
Note:-
In this lab you will monitor the network operation as a call is initiated, connected and terminated. Make sure to record and document every step that you perform and all your observations as you go through the set-up, configuration and troubleshooting procedures.
Equipments:-
1. One ISDN simulator with power supply, straight through RG-45 cable and one DB9 cable.
2. Two ISDN Cisco Router with Power supplies
3. Two PCs
4. One Console cable (DB9 to RJ-45), 2 straight through Ethernets cables
Procedure:-
Figure-01
1. Set-up the circuit as shown in above figure so that PC is connected to a LAN in Toronto (or an ISDN phone) will communicate with a PC connected to a LAN in Ottawa ( or ISDN phone)
2. ISDN simulator provides a U Interface to both TE devices (in this lab case cisco router) and acts as an LT in the ISDN exchange.
What does U interface refer to?
What does S/T interface refer to?
Part-A: Setting up the ISDN simulator and ISDN manager software
1. Connect the simulator to the COM port 1 of the PC with the DB-9 cable and install the ISDN simulator driver software in that PC.
2. Set the hyper terminal connection with the following parameters value
Baud rate 115200 bps
Data bits 8
Parity None
Stop bits 1
Flow control Hardware
In your PC, open the isdn manager screen.
(Start---àProgram ---àVirtual Console-àisdn manager)
3. Now you will get the ISDN manager screen
Figure-02
4. Click the about tab in ISDN manger screen and check the version
What is the version?
5. Set the Switch type to Basic NI-1. List the other switch type this ISDN simulator can simulate.
a.)
b.)
c.)
d.)
What is the function of NT-1 device in ISDN network?
6. To set the individual port characteristics, click on the appropriate port tab.
The screen will then show the current phone numbers and where applicable, the service provider ID (SPID) for each B channel.
Note down the phone number and SPID ID from the ISDN manager screen for port-A and port-B
7. Now connect one of the router’s ISDN BRI port to the simulator’s U port as shown in Figure-01 and connect a PC to the Router via console cable and enter in to the privileged mode of the router.
8. Now see the ISDN status in the router by using the following command
RoterA# show isdn status
9. You will see the following out put.
Figure-03
10. What is it telling you? Is the physical layer active?
11. Configure this router for switch type basic NI-1 using the following cisco commands steps (make sure that you match the SPIDS in the commands with the SPIDS on the simulator screen).
RouterA# configure terminal
RouterA(config)#isdn switch-type basic-ni1
RouterA(config)#interface BRI 0
RouterA(config-if)# no shutdown
RouterA(config-if)#isdn spid1 408111111101
RouterA(config-if)#isdn spid2 408111111102
RouterA(config-if)#ip address 10.10.10.1 255.255.255.0
RouterA(config-if)#dialer map ip 10.10.10.2 broadcast 4082222222
RouterA(config-if)#dialer-group 1
RouterA(config-if)#exit
RouterA(config)#dialer-list 1 protocol ip permit
RouterA(config)# end
RouterA#write mem
12. If your configuration is successful, you should get the output similar to
Figure-04 (use the command following command to view the isdn status)
Router A # show isdn stat
Figure-04
What layers are activated now? Is layer three active? If not, why?
13. Now, do the same configuration for the second router called Router B as follows.
RouterB# configure terminal
RouterB(config)#isdn switch-type basic-ni1
RouterB(config)#interface BRI 0
RouterB(config-if)# no shutdown
RouterB(config-if)#isdn spid1 408222222201
RouterB(config-if)#isdn spid2 408222222202
RouterB(config-if)#ip address 10.10.10.2 255.255.255.0
RouterB(config-if)#dialer map ip 10.10.10.1 broadcast 4081111111
RouterB(config-if)#dialer-group 1
RouterB(config-if)#exit
RouterB(config)#dialer-list 1 protocol ip permit
RouterB(config)# end
RouterB#write mem
Now see the ISDN status of both routers and ISDN manger screen.
RouterB#show isdn status
Figure-05
ISDN manager screen out put
Figure-06
14. Observe the isdn manager screen out put and isdn status of the routers and answer the following questions.
Which layers are active?
What number has been assigned to TEI?
What type of assignment is it?
What is the SAPI?
What does it indicate?
What are the other SAPI values and its descriptions? Make the list.
IS layer 3 active?
15. Check the end to end connectivity by ping each router from each other and see the isdn status of each router
RouterA#ping 10.10.10.2
RouterA #show isdn status
Figure-06
Questions:-
1. What are the signalling messages being exchanged between the calling party and the called party
2. Describe the procedure to establish and terminate the call across an ISDN Network.