1. Introduction 2. Data stream observation 3. Usage Parameter Control

LECTURE:
LECTURER:
YEAR OF STUDY:
SEMESTER:
COURSE:
Telecommunications Networks and Systems
dr inż. Krzysztof Wajda ([email protected]),
mgr inż. Grzegorz Rzym ([email protected])
III
winter
Electronics and Telecommunications
LABORATORY 2 – ATM
1. Introduction
The main goal of this laboratory is to familiarize with the configuration, problems
troubleshooting and management in ATM-LAN network consisting of ATM switch and PCs
with ATM25 cards.
2. Data stream observation
Please set-up channel from PC A to PC B. Next, please observe it in two cases: first – when
40 bytes are send in payload, second – with 41 bytes. To perform this exercise use:
On PC A:
$awrite VPI.VCI 012345678901234567890… (40 i 41 characters)
On PC B:
$atmdump VPI.VCI (in each case)
Q5: How many cells are transmitted in each case? Why? (Each character is 1B size)
(Please compare with slides from lectures – AAL5)
3. Usage Parameter Control
In ForeATM switch you can create virtual connection with SLA (e.g. CBR, VBR). First you
must change UPCs units from cps (cells per second) to kbps with command:
@::configuration system> units
Next, you must create new contract from submenu:
@::configuration upc> new
And new virtual channel. Connect previously created contract ID: use –upc option.
Please observe achieved throughput using ttcp_atm program.
Q6:
What is wrong? Why created contract does not work properly?
Another way to observe real throughput: send data with ttcp_atm and collect it using:
$atmdump VPI.VCI > file_name
Next, count the number of word ‘VPI’ using Linux grep program:
$grep –c VPI file_name
1
LECTURE:
LECTURER:
YEAR OF STUDY:
SEMESTER:
COURSE:
Telecommunications Networks and Systems
dr inż. Krzysztof Wajda ([email protected]),
mgr inż. Grzegorz Rzym ([email protected])
III
winter
Electronics and Telecommunications
Q7: How to calculate the bandwidth? (use output from ttcp_atm, counted cells and
knowledge about ATM cell size). Please write used formula.
Next, please observe used channel statistics:
@::statistics> vcc 1d1
Q8:
Why cells are dropped?
4. Congestion control
Please create virtual channels to send data in loops like in the picture below:
Use e.g. ttcp_atm program to send and receive data stream. Next observe statistics in each
point of created loops.
Q9: Please write used commands to create this loops.
Q10: Why cells are dropped?
Q11: How can we solve this problem?
2
LECTURE:
LECTURER:
YEAR OF STUDY:
SEMESTER:
COURSE:
Telecommunications Networks and Systems
dr inż. Krzysztof Wajda ([email protected]),
mgr inż. Grzegorz Rzym ([email protected])
III
winter
Electronics and Telecommunications
5. Encapsulation
The mail goal of this exercise is to create heterogeneous network consisting of Ethernet and
ATM switches and provide cooperation among them. Picture presented below shows used
configuration:
a) PCA and PCB have two different ethernet interfaces called eth0 and eth1. Both are
connected to the same etherent Cisco switch (eth0 is used for PCs’ management).
Please configure eth1 interfaces on both PCs in order to get direct communication.
Used IPs should be taken from private IP address pool:
PCA: ifconfig eth1 192.168.1.1/30
PCB: ifconfig eth1 192.168.1.2/30
b) Then set up different VLANs on Cisco switch interfaces. Now communication
between PC should be disabled.
c) After that please create new channel on the ATM switch.
d) Finally, configure Cisco Catalyst switch with ATM card as shown below:
 ATM card configuration:
switch# session 1

ATM interface configuration submenu:
ATM(config)#interface atm 1

Creation of new ATM PVC
ATM(config-if)# atm pvc PVC_ID_1 VPI_1 VCI_1 aal5snap
ATM(config-if)# atm pvc PVC_ID_2 VPI_2 VCI_2 aal5snap

where: VPI_1 (VPI_2) and VCI_1 (VCI_2) have to have identical VPIs
and VCIs like previously created channels in ForeSystems switch.
Binding of ATM channels witch VLANs:
ATM(config-if)# atm bind pvc vlan PVC_ID_1 20
ATM(config-if)# atm bind pvc vlan PVC_ID_2 30
e) Next try to ping each other. Please use tcpdump program if any problem occurs.
Q12: Please briefly describe the exact path that ICMP packet traverses (please note
the accurate description of connection between ATM and Ethernet network).
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