Spirent Test Methodology VoIP
TestMethodology Journal Methodolo
VoIP (Voice over IP)
September 2006
Spirent Communications Voice over IP (VoIP)
2
VoIP Call Setup Rate
• IETF RFC 3261 (Session Initiation Protocol)
Objective
Test will determine the maximum setup rate for Voice over IP (VoIP) calls that can be established
through a DUT (Device under Test.)
Description
This test is an end to end VoIP setup with calls forwarded by a DUT in the middle where the rate of
the call establishment is measured. Calls can be generated and terminated by the abacus
system.
Materials Needed
• Abacus 5000 with ICG3 Card
• DUT
Setup
Steps
1. Configure the Abacus to emulate many VoIP calls (originating and terminating).
2. Configure DUT to forward VoIP traffic.
3. Set your call length to “0” so that calls terminate immediately after establishment
4. Start generating calls through the “DUT” at highest rate possible.
5. Measure the call setup rate through the DUT
6. Repeat test with a mixture of protocols such as SIP, H.323 and IP versions 4 and 6.
7. Use a graph to map your call setup rates vs. time entries.
Variables
• Number of VoIP clients
• IP addressing IPv4, IPv6
• VoIP protocols SIP or H.323
• Use of a proxy or gatekeeper
Report Results
• Call setup rate Call/s
Abacus
DUT Originate Terminate
Spirent Communications Voice over IP (VoIP)
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Graph
Figure 1: Voice Quality
As number of calls increases the rate setup decreases.
Spirent Communications Voice over IP (VoIP)
4
Converged VoIP and Data Test
• IETF RFC 3261 (Session Initiation Protocol)
• ITU-T Recommendation H.323
Objective
Test the quality of VoIP calls as data and media is introduced to the same network.
Description
An end to end VoIP setup with calls forwarded by a Device Under Test (DUT) in the middle. The
DUT will prioritize VoIP calls while media traffic is increased gradually and voice quality
measured.
Materials Needed
• Abacus 5000 with Voice Quality Testing and “ACT” card for voice and data convergence
• DUT
• Avalanche (Layers 4-7)
Setup
Steps
1. Configure an Abacus to emulate one more VoiP calls (originating and terminating)
2. Enable the voice quality measurement tool in the Abacus.
3. Set the voice to be high priority traffic in the DUT.
4. Set the VoIP clients with the same connection setting as data.
5. Configure the DUT to forward the VoIP with the highest priority.
6. Generate calls at a high rate, measure the quality from your first scenario and so on.
7. Abacus can generate “Voice with data” traffic or if you want to test higher layers of media traffic
(Layers 4-7 (FTP, TFTP, RTSP, SMTP etc.)), use the Avalanche Tool. Increase it gradually with
Voice quality measurements done periodically.
8. Repeat the test for a mixture of protocols and record findings
9. Use a graph to map your results in Voice Quality Vs Time.
Abacus
DUT Originate Terminate
Spirent Communications Voice over IP (VoIP)
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Variables
• IP addressing IPv4, IPv6
• VoIP protocols SIP or H.323
• Prioritization method (TOS)
• Use of stateful data Traffic (HTTP, FTP, SMTP etc.)
• RTP payload length and content
• Speech Coding
Test Results
• Throughput
• Packet Loss
• Jitter
• Packet Delay
Graph
Figure 1: Voice Quality
As media increases, voice quality decreases.
Spirent Communications Voice over IP (VoIP)
6
VoIP test during DoS attacks
• IETF RFC 3261 (Session Initiation Protocol)
Objective
Test will determine the effect of Denial of Service (DoS) attacks have on Voice over IP (VoIP) calls
through a Device Under Test (DUT).
Description
This test is an end to end VoIP setup with calls forwarded by a DUT in the middle. Several types
of DoS attacks are performed. VoIP performance is measured while the DoS attacks are
introduced. Calls can be generated and terminated by the Abacus system.
Materials Needed
• Abacus 5000 with ICG3 Card
• Spirent ThreatEx Attack Tool
• DUT
Setup
Spirent Communications Voice over IP (VoIP)
7
Steps
1. Configure the Abacus to emulate many VoIP calls (originating and terminating).
2. Configure DUT to forward VoIP traffic while blocking DoS attacks.
3. Start generating calls through the “DUT” at highest rate possible.
4. Measure the call setup rate and traffic delay through the DUT
5. Start generating a variety of attacks to the DUT (with the Spirent ThreatEx attack tool) and measure
the impact in the voice quality and performance.
6. Attacks can be but not limited to DoS attacks
7. Repeat test with a mixture of Protocols SIP, H.323.
8. Use a graph to map your number of attacks vs. voice performance.
Variables
• Number of VoIP clients
• Different types of DoS attacks
• IP addressing IPv4, IPv6
• VoIP protocols SIP or H.323
• Use of a proxy or gatekeeper
Report Results
• End to end delay
• Call Setup rate Call/s
• Packet Loss
• Jitter (ms)
Graph
Spirent Communications Voice over IP (VoIP)
8
VoIP Performance with NAT
• IETF RFC 3261 (Session Initiation Protocol)
• IETF RFC 3022 (Traditional IP Network Address Translator – NAT)
Objective
This test will determine the maximum number of Voice over IP (VoIP) calls that can be established
through a DUT (Device under Test) while NAT (Network Address Translation) is enabled.
Description
An end to end VoIP setup with calls forwarded by a DUT in the middle with NAT enabled. One side
of clients will have private IP addresses while the other side will have public IP addresses. The
DUT will translate IP addresses between a public side and the private side and vice versa. Call
can originate from either side.
Materials Needed
• Abacus 5000 with ICG3 Card
• DUT
Setup
Abacus
DUT Originate Terminate
Spirent Communications Voice over IP (VoIP)
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Steps
1. Configure the Abacus to emulate many VoIP calls (originating and terminating).
2. Clients on one side of the configuration (see diagram) should be configured with private IP
address and TCP ports while the clients on the other side of the configuration should use public
(translated) addresses and TCP ports.
3. Configure DUT to forward VoIP traffic with NAT (Network address translation) enabled.
4. Generate calls starting with one call and increasing your volume of calls until the maximum
effective NAT table size is determined in the DUT.
5. Use a graph to map your results in Number of calls vs. NAT table entries.
Variables
• Number of VoIP clients
• IP addressing IPv4, IPv6
• VoIP protocols SIP or H.323
• Number of private IP addresses and TCP Ports
Report Results
• NAT Table size
• Throughput MB/S
• Number of calls completed
• End to end delay
• Packet Loss and Jitter
Graph
Figure 1: Voice Quality
As number of calls increases the quality decreases as you reach the limit of NAT table.
Spirent Communications Voice over IP (VoIP)
10
VoIP Performance over IPsec
• IETF RFC 3261 (Session Initiation Protocol)
• IETF RFC 2401 and 2412 (Security architecture for the Internet Protocol - IPSEC)
• ITU-T Recommendation H.323
Objective
Test will determine the maximum number of IPsec VPNs that can be established through a DUT
(Device under Test) before call setup degradation.
Description
This is an end to end VoIP setup with calls forwarded by a DUT in the middle through IPsec VPN
tunnels between clients. While the number of IPsec tunnels increases, the VOIP quality is
measured.
Materials Needed
• Abacus 5000 with ICG3 card VPN enabled
• DUT with IPsec VPN server
Setup
Steps
1. Configure the Abacus to emulate many VoIP calls (originating and terminating).
2. Clients on one side of the configuration (see diagram) should be configured with IPsec VPN to
synchronize with the DUT.
3. Configure DUT to Synchronize IPsec tunnels with the originating side of the test plan. In the DUT,
set the lowest level of encryption then increase as test cases are completed.
4. Generate calls using the IPsec VPN configuration on the originating interface starting with one
call and increasing your volume until the maximum number of tunnels is achieved before of VoIP
degradation.
5. Use a graph to map your results in number of IPsec tunnels vs. VoIP quality.
Spirent Communications Voice over IP (VoIP)
11
Variables
• Number of VoIP clients
• Number of VoIP clients per IPsec tunnel
• IPsec encryption level
• Audio codec type
• RTP payload (Packet length and content)
• VoIP protocols SIP or H.323
• IPv6 or (IPv4 and IPv6) addressing
• Call duration
Test Outcome
• Call setup rate (call/s)
• Number of IPsec tunnels
• Throughput MB/S
• End to end delay
• Packet Loss and Jitter
Graph
Figure 1: Voice Quality
As number of IPsec tunnels increases the VoIP quality decreases as you reach the limit of VPNs.
Spirent Communications Voice over IP (VoIP)
12
Maximum Concurrent VoIP Calls
• IETF RFC 3261 (Session Initiation Protocol)
Objective
Test will determine the maximum number of VoIP (Voice over IP) calls that can be established
through a (DUT) Device Under Test.
Description
This test is an end to end VoIP setup with calls forwarded by a DUT in the middle. Calls can be
generated and terminated by the abacus system.
Materials Needed
• Abacus 5000 with ICG3 Card
• DUT
Setup
Test Steps
1. Configure the Abacus to emulate many VoIP calls (originating and terminating).
2. Configure DUT to forward VoIP traffic.
3. Generate calls starting with one call and increasing your volume until the maximum number of
calls is determined in the DUT.
4. Use a graph to map your results in number of calls vs. time entries.
Variables
• Number of VoIP clients
• IP addressing IPv4, IPv6
• Voice codec type
• VoIP protocols SIP or H.323
• Use of a proxy or gatekeeper
Results
• RTP throughput MB/S
• Maximum number of calls completed
• End to end delay
• Packet Loss and Jitter
Abacus
DUT Originate Terminate
Spirent Communications Voice over IP (VoIP)
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Graph
The number of calls increases gradually until the max is reached as Voice Quality decreases.
© 2006 Spirent Communications, Inc. All of the company names and/or brand names and/or product names referred to in this
document, in particular the name “Spirent” and its logo device, are either registered trademarks or trademarks pending registration
in accordance with relevant national laws. All rights reserved. Specifications subject to change without notice.
Rev A, 9/06
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