Testing PPPoX and L2TP Broadband Access Devices - Ixia

Testing PPPoX and L2TP
Broadband Access Devices

Contents
1. PPPoX Client Performance and Scalability Test·········································································· 1
1.1 Objective ······················································································································ 1
1.2 Setup··························································································································· 1
1.3 Input Parameters············································································································ 2
1.4 Test Methodology and Result Generation ············································································ 2
2.. PPPoX Client and Server Performance and Scalability Test·························································· 7
2.1 Objective ······················································································································ 7
2.2 Setup··························································································································· 7
2.3 Input Parameters············································································································ 7
2.4 Test Methodology and Result Generation ············································································ 7
3. LNS Performance and Scalability Test······················································································· 8
3.1 Test Objective ··············································································································· 8
3.2 Setup··························································································································· 8
3.3 Input Parameters············································································································ 8
3.4 Test Methodology and Result Generation ············································································ 9
4. LAC Performance and Scalability Test····················································································· 12
4.1 Test Objective ············································································································· 12
4.2 Setup························································································································· 12
4.3 Input Parameters·········································································································· 12
3.4 Test Methodology and Result Generation ·········································································· 13
Copyright © 2004 by Ixia
All rights reserved
IXIA
26601 West Agoura Road, Calabasas, CA 91302
(877) FOR-IXIA
This Test Plan Primer contains a general outline for testing a particular technology. Not all the capabilities of Ixia
technology have been exposed in this document. Please feel free to contact us if additional capabilities are required.

Overview
Modern broadband networks deployed to provision xDSL
or cable-based high-speed Internet access services to
residential and commercial users rely on a number of
complex devices to offer a high quality experience to the
user. Prior to network deployment, these devices are
commonly tested for:
• Performance, e.g. can the device handle a specified
number of session setup requests per second
• Scalability, e.g. does the device meet its maximum
session specifications
• Functionality, e.g. do the advanced firmware features in
the device interoperate with other parts of the network
while maintaining scalability
This document provides test case examples covering these
requirements for three main device classes, namely:
• Broadband Remote Access Servers (BRAS)
• Layer 2 Access Servers
• Layer 2 Network Servers
Four iterative test case examples are being presented.
• PPPoX client performance and scalability test
• PPPoX client and server performance and scalability test
• L2TP LAC performance and scalability tests with
PPPoX traffic
• L2TP LNS performance and
scalability tests
PPPoX includes a number of
technologies such as PPPoE,
PPPoA, PPPoEoA, PPPoEoVLAN.
The PPPoX version tested depends
on the interface options available in
the Device under Test (DUT)/
System under Test (SUT) and the
corresponding Ixia Load Module.
While the total number of PPPoX
sessions needed to perform stress
tests depends on capabilities of the
DUT, this document assumes that
the test tool is capable of generating
32,000 sessions per test.
1. PPPoX Client Performance
and Scalability Test
1.1 Objective
The objective of this test is to characterize the performance
of both LAC and LNS/B-RAS devices while simulating
32,000 PPPoX sessions. The test is split into three phases,
namely:
• Baseline session setup and teardown tests.
• Simulating access link failure test. This can be achieved
by simply disconnecting and reconnecting the link
from the test tool to the DUT to observer service
recovery times.
• Simulate DUT failure test. This can be achieved by
re-booting the DUT.
1.2 Setup
The DUT may consist of single or multiple devices (i.e.
Access concentrator/LAC and LNS or LNS or BRAS, etc.).
As shown in Figure 1, an Ixia GigE Load Module port
(copper or fiber) or ATM Load Module port (OC3 or
OC12) may be used to generate the required number
of subscribers (access users) for one or more PPPoX
sessions.
Figure 1: PPPoX client emulation setup
PoE Test Plan Copyright © Ixia, 2004 1

1.3 Input Parameters
The primary input parameters for each phase include:
• Session setup rate & latency – maximum, minimum and
average time and latency to establish all sessions with
either no authentication, PAP or CHAP authentication for
PPPoX clients (access side only).
• Interfaces, VLANs and domain groups.
• Traffic generation – upstream/downstream/bi-directional
for stateless L3/L4 traffic (IMIX or fixed frame
distributions).
• Session teardown rate.
1.4 Test Methodology and Result
Generation
• Session setup test:
− Test tool to generate 32,000 PPPoX sessions.
− Record setup rates and latency measurements.
See Figures 2 and 3 below for details.
Figure 2: Session setup results configuration
The connection rate chart in the test tool displays the number and
rate of PPPoX connections, number of active sessions, and the
number of sessions that are in the discovery or negotiation stage.
2 Copyright © Ixia, 2004 PoE Test Plan

Figure 3: Latency results
− Record the number of sessions in the DUT.
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• Traffic generation over PPPoX test:
− Test tool to generate L2/3 stateless traffic. For
example, 20% upstream and 80% downstream
IMIX traffic (64, 128, 512, 1024 and 1518 byte
frames over TCP). See Figure 4 for setup details.
Figure 4: Stateless traffic generation options in Test tool
4 Copyright © Ixia, 2004 PoE Test Plan

• Record throughput results. See Figure 5 for example of
graphical representation of results.
Figure 5: Test tool stateless traffic generation chart
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• Session tear down test:
− Test tool to tear down sessions at a fixed rate (e.g.
100 sessions per second). See Figure 6 for details.
•
Figure 6: PPP session tear down
6 Copyright © Ixia, 2004 PoE Test Plan

• Simulate an access link failure for each of the above test
cases. Note the number of session retries and session
recovery times.
• Simulate a system failure for each of the above test
cases.
Note the number of session retries and session recovery
times.
2. PPPoX Client and Server
Performance and Scalability Test
2.1 Objective
The objective of this test is to characterize the performance
of both LAC and LNS/B-RAS devices when forwarding
32,000 PPPoX sessions including both control and data
plane traffic. The test is split into two phases, namely:
• Control plane traffic generation (PPPoE, PPPoA,
PPPoEoA, PPPoEoVLAN).
• Data plane traffic generation (IMIX and fixed frame sizes
at 100% utilization).
2.2 Setup
When emulating both client and server, the test tool creates
the requested number of subscribers (i.e. 32,000 in this
case) as well as terminates the incoming PPP sessions,
thus bracketing the DUT. The DUT may consist of single or
multiple devices (e.g. DSLAM).
As shown in Figure 7, an Ixia GigE Load Module port
(copper or fiber) or ATM Load Module port (OC3 or OC12)
may be used to generate the required number of PPP
sessions. In addition, these ports generate the data plane
IP traffic.
2.3 Input Parameters
The primary input parameters for each phase include:
• Session setup rate & latency – maximum, minimum and
average time and latency to establish all sessions with
either no authentication, PAP or CHAP authentication.
• Interfaces, VLANs and domain groups for access and
network ports.
• Traffic generation – upstream/downstream/bi-directional
for stateless L3/L4 traffic (IMIX or fixed frame
distributions).
• Session teardown rate.
2.4 Test Methodology and
Result Generation
• Session setup test:
− Test tool to generate 32,000 PPPoX sessions.
− Record setup rates and latency measurements
outlined in section 1.2.
− Record the number of sessions in the DUT.
• Traffic generation over PPPoX test:
− Test tool to generate L2/3 stateless traffic. For
example, 20% upstream and 80% downstream
IMIX traffic (64, 128, 512, 1024 and 1518 byte
frames over TCP). See Figure 3 in Section 1 for
setup details.
• Session tear down test:
− Test tool to tear down sessions at a fixed rate
(e.g. 100 sessions per second).
Access Side
- PPPoE, PPPoEo802.1q
- PPPoEoA, PPPoA
DUT
Access Concentrator
Network Side
- PPPoE, PPPoEo802.1q
- PPPoEoA, PPPoA
10/100/1000 Ethernet
Or OC3/OC12 ATM
10/100/1000 Ethernet
Or OC3/OC12 ATM
Figure 7: PPPoX client and server emulation setup
PoE Test Plan Copyright © Ixia, 2004 7

3. LNS Performance and
Scalability Test
3.1 Test Objective
The objective of this test is to emulate multiple LACs to
characterize the performance of LNS devices when
forwarding 32,000 PPPoX sessions including both control
and data plane traffic. The test is split into four phases,
namely:
• L2TP Tunnel setup, i.e. the rate at which the LNS can
terminate 32,000 tunnels.
• Tunneled session setup phase, i.e. the rate at which the
LACs can initiate 16k L2TP tunnels with or without
PAP/Chap authentication.
• PPPoX session establishment through L2TP tunnels.
• Data plane and keep-alive traffic generation (IMIX and
fixed frame sizes at 100% utilization).
3.3 Input Parameters
The primary input parameters for each phase include:
• PPPoXsession setup rate & latency – maximum,
minimum and average time and latency to establish all
sessions with either no authentication, PAP or CHAP
authentication.
• PPPoX interfaces, VLANs and domain groups for access
and network ports.
• L2TP sessions per tunnel, Hello Request intervals and
L2TP data plane options (e.g. UDP source and
destination ports).
• Traffic generation – upstream/downstream/bi-directional
for stateless L3/L4 traffic (IMIX or fixed frame
distributions).
• Session teardown rate.
3.2 Setup
In this test, Test tool emulates multiple LACs creating up to
32,000 L2TP tunnels and then running PPPoX session and
data traffic over those tunnels. As depicted in Figure 8,
either Ixia Ethernet or ATM ports may be used to simulate
the number of subscribers on the access side of the LNS.
The network side of the LNS is also connected to either Ixia
ATM or Ethernet ports to receive or generate IP traffic.
Access Side
- PPPoEoL2TP
- PPPoEo802.1qoL2TP
- PPPoAoL2TP
- PPPoAoL2TPoA
LNS
Network Side
- IP (Ethernet, VLAN or
ATM RFC 1483)
10/100/1000 Ethernet
Or OC3/OC12 ATM
10/100/1000 Ethernet
Or OC3/OC12 ATM
10/100/1000 Ethernet
Or OC3/OC12 ATM
Figure 8: PPPoX client emulation setup
8 Copyright © Ixia, 2004 PoE Test Plan

3.4 Test Methodology and
Result Generation
• Session setup test:
− Test tool to emulate a specified number of LACs
with the parameters outlined in Figure 9 below.
− Test tool to generate 32,000 L2TP sessions. See
Figure 10 for a graphical representation of 32,000
active sessions spread over 24,000 L2TP tunnels.
− Test tool to generate 32,000 PPPoX sessions.
− Record setup rates and latency measurements
outlined in section 1.2. See Figures 2 and 3
for details.
− Record the number of sessions in the DUT.
Figure 9: LAC parameter definition
PoE Test Plan Copyright © Ixia, 2004 9

Figure 10: 32,000 L2TP sessions over 24,000 tunnels
10 Copyright © Ixia, 2004 PoE Test Plan

• Traffic generation over PPPoX test:
− Test tool to generate L2/3 stateless traffic. For
example, 20% upstream and 80% downstream
IMIX traffic (64, 128, 512, 1024 and 1518 byte
frames over TCP). See Figure 3 in Section 1 for
setup details.
• Session tear down test:
− Test tool to tear down sessions at a fixed rate (e.g.
100 sessions per second). See Figure 11 for details.
Figure 11: L2TP session/tunnel teardown
PoE Test Plan Copyright © Ixia, 2004 11

4. LAC Performance and
Scalability Test
4.1 Objective
The objective of this test is measure the performance of
LAC devices when forwarding 32,000 PPPoX sessions
including both control and data plane traffic (including keepalives)
over 32,000 L2TP tunnels. The test tool in LNS
emulation mode allows the user to terminate both LAC
initiated tunnels and PPPoX sessions. The test is split into
three steps, namely:
• Tunneled session setup phase, i.e. the rate at which the
LACs can initiate 16k L2TP tunnels with or without
PAP/Chap authentication.
• PPPoX session establishment through L2TP tunnels.
• Data plane and keep-alive traffic generation (IMIX and
fixed frame sizes at 100% utilization).
4.2 Setup
In this test, Test tool emulates multiple PPPoX clients
creating up to 32,000 PPP sessions on the access side
and terminate 32,000 L2TP and PPPoX sessions coming in
from the DUT (LAC). The network side of the LNS is also
connected to either Ixia ATM or Ethernet ports to receive
or generate IP traffic.
4.3 Input Parameters
The primary input parameters for each phase include:
• PPPoXsession setup rate & latency – maximum,
minimum and average time and latency to establish all
sessions with either no authentication, PAP or CHAP
authentication.
• PPPoX interfaces, VLANs and domain groups for access
and network ports.
• L2TP sessions per tunnel, Hello Request intervals and
L2TP data plane options (e.g. UDP source and
destination ports).
• Traffic generation – upstream/downstream/bi-directional
for stateless L3/L4 traffic (IMIX or fixed frame
distributions).
• Session teardown rate.
Access Side
- PPPoE
- PPPoEo802.1q
- PPPoA
BRAS
Network Side
- IP (Ethernet, VLAN or
ATM RFC 1483)
10/100/1000 Ethernet
Or OC3/OC12 ATM
10/100/1000 Ethernet
Or OC3/OC12 ATM
10/100/1000 Ethernet
Or OC3/OC12 ATM
12 Copyright © Ixia, 2004 PoE Test Plan

4.4 Test Methodology and
Result Generation
• Session setup test:
− Test tool to generate 32,000 PPPoX sessions.
− Record setup rates and latency measurements
outlined in section 1.2.
− Record the number of L2TP sessions being
terminated on the network port.
• Traffic generation over PPPoX test:
− Test tool to generate L2/3 stateless traffic. For
example, 20% upstream and 80% downstream IMIX
traffic (64, 128, 512, 1024 and 1518 byte frames
over TCP).
• Session tear down test:
− Test tool to tear down sessions at a fixed rate
(e.g. 100 sessions per second).
PoE Test Plan Copyright © Ixia, 2004 13