Spirent Journal of Mobile Backhaul PASS Test Methodologies
Ethernet is the layer 2 technology choice for backhaul, whether it is delivered over microwave, fiber, or copper. Network operators gain significant advantage in migrating from classic TDM circuits onto new Ethernet-based technologies. Mobile backhaul is a collection of technologies that enable classic switched-circuit emulation over modern Ethernet/IP based solutions. This journal presents a comprehensive set of test cases to measure PASS of the Device Under Test (DUT).
PASS
Spirent Journal of Mobile
Backhaul PASS Test
Methodologies
February 2011 Edition
Spirent Journal of Mobile Backhaul PASS Test Methodologies | © Spirent Communications 2011
1
Introduction
Today’s Devices Under Test (DUT) represent complex, multi-protocol network elements with an emphasis
on Quality of Service (QoS) and Quality of Experience (QoE) that scale to terabits of bandwidth across the
switch fabric. The Spirent Catalogue of Test Methodologies represents an element of the Spirent test
ecosystem that helps answer the most critical Performance, Availability, Security and Scale Tests (PASS)
test cases. The Spirent Test ecosystem and Spirent Catalogue of Test Methodologies are intended to help
development engineers and product verification engineers to rapidly develop and test complex test
scenarios.
How to use this Journal
This provides test engineers with a battery of test cases for the Spirent Test Ecosystem. The journal is
divided into sections by technology. Each test case has a unique Test Case ID (Ex. TC_MBH_001) that is
universally unique across the ecosystem.
Tester Requirements
To determine the true capabilities and limitations of a DUT, the tests in this journal require a test tool that
can measure router performance under realistic Internet conditions. It must be able to simultaneously
generate wire-speed traffic, emulate the requisite protocols, and make real-time comparative
performance measurements. High port density for cost-effective performance and stress testing is
important to fully load switching fabrics and determine device and network scalability limits.
In addition to these features, some tests require more advanced capabilities, such as
Integrated traffic, routing, and MPLS protocols (e.g., BGP, OSPF, IS-IS, RSVP-TE, LDP/CR-LDP) to
advertise route topologies for large simulated networks with LSP tunnels while simultaneously
sending traffic over those tunnels. Further, the tester should emulate the interrelationships
between protocol s through a topology.
Emulation of service protocols (e.g., IGMPv3, PIM-SM, MP-iBGP) with diminution.
Correct single-pass testing with measurement of 41+ metrics per pass of a packet.
Tunneling protocol emulation (L2TP) and protocol stacking.
True stateful layer 2-7 traffic.
Ability to over-subscribe traffic dynamically and observe the effects.
Finally, the tester should provide conformance test suites for ensuring protocol conformance and
interoperability, and automated applications for rapidly executing the test cases in this journal.
Further Resources
Additional resources are available on our website at http://www.spirent.com
Spirent Journal of Mobile Backhaul PASS Test Methodologies | © Spirent Communications 2011
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Table of Contents
Testing Mobile Backhaul ........................................................................................................3
MBH_001 Determine whether the DUT incorrectly reflects traffic to the UNI ..................... 5
MBH_002 Peak unicast traffic capacity across the EVC ...................................................... 9
MBH_003 Determine whether the DUT leaks traffic across EVCs ..................................... 13
MBH_004 Determine maximum EVC circuit capacity while maintaining QoS profile ....... 16
MBH_005 Determine whether the DUT blocks invalid traffic over the EVC ...................... 19
MBH_006 Measure accuracy of IEEE 1588v2 boundary clock timing ................................ 22
MBH_007 Determine IEEE 1588v2 slave clock capacity .................................................... 25
MBH_008 Scalability of IEEE 1588v2 clocks over VPLS ...................................................... 28
MBH_009 Duplicate clock identity detection in IEEE 1588v2 ............................................. 31
MBH_010 Determine whether the 1588v2 grand master clock is resilient to DDoS attacks
34
MBH_011 Measure 1588v2 boundary clock timing accuracy when using GPS as the grand
master timing source ......................................................................................... 37
MBH_012 Measure 1588v2 boundary clock timing accuracy in presence of impairments 41
Appendix A – Telecommunications Definitions ..................................................................... 44
Appendix B – Layer 2 802.1q CoS .......................................................................................... 51
Appendix C – RFC 2474 Layer 3 QoS ...................................................................................... 52
Appendix D – RFC 2474 Layer 3 QoS Definitions .................................................................... 53
Spirent Journal of Mobile Backhaul PASS Test Methodologies | © Spirent Communications 2011
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Testing Mobile Backhaul
Ethernet is the layer 2 technology choice for backhaul, whether it is delivered over microwave, fiber, or
copper. Network operators gain significant advantage in migrating from classic TDM circuits onto new
Ethernet-based technologies. Mobile backhaul is a collection of technologies that enable classic switched-
circuit emulation over modern Ethernet/IP based solutions.
Although the potential benefits of mobile backhaul technologies are understood, mobile backhaul
infrastructures are also subject to a
number of success factors, including:
LATENCY / JITTER. Mobile backhaul is
part of the overall Radio Access
Network (RAN), which has a tightly
controlled delay budget. This ensures
that voice services meet quality
criteria for ease of conversation and
assures the response time of mobile
data services and RAN control
protocols. Since the delay budget of
the end-to-end RAN is in the order of 100 milliseconds, the delay of the backhaul segment between the
base transceiver station (BTS) and base station controller (BSC) must be kept as low as 3–5 milliseconds
for some applications.
REAL-TIME DROP FRAME SENSITIVITY. This value depends on the nature of the supported service. Where the
existing PDH/SDH leased-line infrastructure is to be emulated, the effective random bit-error ratio
(ERBER) is 1 x 10–7 end-to-end or per-segment, which is similar to the in-service criteria for a transport
network. In an evolved 3G Node B where voice and data services may be transported directly over IP and
Ethernet, the loss criteria drops to 10–5 and 10–4 respectively for acceptable throughput and performance.
SYNCHRONIZATION/TIMING. To maintain licensed radio frequency accuracy and insure that inter-cell handoffs
are manageable by the widest range of affordable handsets, every BTS in a 2G network (or Node B in a 3G
network) must be able to trace frequency synchronization back to a primary reference clock (PRC) source
in normal operation. Failure to do this can result in a mobile device losing lock, which can adversely affect
voice and data services or result in dropped calls. The required performance is based on a relative
degradation of the PRC by existing transport systems. The standards for E1/T1 jitter and wander
impairments are defined in ITU-T G.823/G.824/G.825 for traffic interfaces and SONET/SDH transport.
Adhering to the standards avoids the need to perform significant upgrades of the existing mobile
infrastructure.
AVAILABILITY UNDER COMPLEX LAYERED PROTOCOLS. Mobile backhaul networks were designed and built on the
assumption that the transport network will meet a four-nines or five-nines network availability target.
This requires a range of protection mechanisms capable of sub 50 millisecond recovery when outages
occur and the mean-time-to-repair (MTTR) target is typically two to three hours.
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This chapter describes the definitive approach to classifying, testing and analyzing mobile backhaul while
under extreme scale in a realistic test environment. Test cases include Timing, Performance, Availability,
Scalability, and Security test categories.
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MBH_001 Determine whether the DUT incorrectly reflects traffic
to the UNI
Abstract
This test determines whether the Metro Ethernet Network (MEN) established on the DUT
incorrectly reflects traffic back to the originating UNI. The test sets up a MEN across the DUT and
transmits traffic across a range of frame sizes and loads to determine whether the DUT
incorrectly transmits traffic back to the source User Network Interface (UNI). This test reveals
incorrect behavior of the DUT when processing UNI traffic. Incorrect processing of reflected
traffic can lead to incorrect MEN behavior, incorrect counters and corrupted services.
References: MEF 1 Section 7.5.1, MEF 9. For product verification and engineering.
Description
A MEN (Metro Ethernet network) is an end-user point-to-point and point-to-multipoint service
that tunnels user traffic across the metro Ethernet cloud. The tunnel created is called an EVC
(Ethernet Virtual Circuit) and is identified by Q-in-Q VLAN tags, generally referred to as CE-VLAN
ID. In this test case, the test determines whether the DUT incorrectly reflects data back to the
originating host. In addition, the test determines whether, in the presence of reflected data,
there are secondary effects on valid traffic such as lost, duplicated, or reordered traffic. The test
case also measures real-time average latency for valid traffic in the presence of incorrectly
reflected traffic.
The test case scans through a set of frame size, traffic load and random frame size, load, and
bursts options to determine whether ingress traffic patterns cause the DUT to incorrectly reflect
traffic. One-to-many and full-mesh patterns are used to determine whether mesh and bi-
directional traffic result in incorrect traffic reflection.
Relevance
Incorrectly reflected traffic slows service performance transiting over the MEN / EVC
Incorrect reflection causes unnecessary data processing by the DUT
Can confuse lower lever services like TCP and UDP stacks.
Version
1.0
Test Category
Mobile Backhaul.
PASS
[x] Performance [x] Availability [ ] Security [ ] Scale
Spirent Journal of Mobile Backhaul PASS Test Methodologies | © Spirent Communications 2011
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C E - V L A N 1 0
D e v i c e U n d e r T e s t ( D U T )
C E - V L A N 1 0
C E - V L A N 1 1
C E - V L A N X
E V C 1 - X
E V C 1
E V C 2
E V C 3
T r a f f i c F l o w
K e y
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C E - V L A N
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Required Tester Capabilities
The test equipment should have the ability to create EVC circuits across the DUT cloud and be
able to make live changes to traffic content.
Topology
Test Procedure
1. Reserve two test ports.
2. Connect cabling to the DUT. Connect tester port 1 to the configured edge of the MEN-
capable DUT. Connect Port 2 to the core side of DUT. Establish the link.
3. On the DUT, configure EVCs using 2 Q-in-Q tags. The CE-VLAN IDs should range from {1-
4095} for the outer VLAN tag and {1-4095} for the inner VLAN tag. There is a potential of
4095^2 MENs on the DUT.
4. Begin Step 1 – Setup basic traffic using the outer tag as a variable.
a. On tester port 1, setup a single host with a starting VLAN ID of (1,1).
b. On tester port 2, setup a single host with a staring VLAN ID of (1,1).
c. Setup bi-directional traffic at 1% of load with 78-byte frames. Traffic sourced on port 1 is
sent only to port 2, and traffic sourced on port 2 is sent only to port 1.
d. Setup traffic mode to Burst of 120 seconds.
5. Begin Step 2 – Test the effect of burst, load, and frame size.
a. Set the range of hosts (one host per outer VLAN tag) to range from {1-4095}.
b. Set the Burst Count (Inter-burst rate = Line rate) to the range {1,5,10,11,20,100,1000}.
c. Set the frame size to range from {78-1518 Step 64, 9022}.
d. Set the load range to (1%, 33%, and 100%).
e. Test all permutations of ranges.
f. Within each permutation.
i. Clear the counters.
ii. Transmit traffic.
iii. Look for mis-switched frames on all ports.
iv. Look for sequencing errors on port 2.
v. Look for real-time latency spikes, correlated to sequencing errors.
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6. Begin Step 3 – Determine whether the inner tag affects incorrect traffic reflection.
a. For each outer CE-VLAN ID created in Step 3, create 4095 hosts, each with the same
outer tag, but a unique Inner tag ranging from {1-4095}.
b. Create a single stream from outer VLAN, but create a partial mesh between all inner tag
hosts (1 Stream containing 4095 x 4095 flows).
c. Set the burst count (Inter burst rate = Line rate) to the range {1,5,10,11,20,100,1000}.
d. Set the frame size to range from {78-1518 Step 64, 9022}.
e. Set the load range to (1%, 33%, and 100%).
f. Test all permutations of ranges.
g. Within each permutation.
i. Clear the counters.
ii. Transmit traffic.
iii. Look for mis-switched frames on all ports.
iv. Look for sequencing errors on port 2.
v. Look for real-time latency spikes, correlated to sequencing errors.
7. Begin Step 4 – Effects of randomness on incorrectly reflected traffic.
a. Starting with the traffic pattern generated in Step 3, set the load {1%-line rate} and
frame size in bytes {78-1518} to random.
b. Clear all counters.
c. Generate traffic continuously for 12 hours.
d. At random intervals, reduce the host count by 20% without stopping traffic.
e. Wait a random time from 6 to 10 minutes.
f. Add back the removed hosts along with the traffic patterns.
g. Start re-added hosts.
h. Examine mis-switched packets, sequencing errors, and real-time latency results.
8. End.
Variables & Relevance
Variable Relevance
MEN CE-VLAN Outer Tag {1..4095} Represents unique customers across the DUT
Rate, Frame Size, Burst Count Places the CAM tables in different permutations of stress
Mis-switched Frames Frames that were reflected back to the MEN
Host Count Examine the effect of the DUT removing hosts from CAM
tables and re-adding upon incorrect traffic reflection
Desired Result
At no time should the user see reflected packets across the DUT back on the TX port. Further,
there should be no sequencing errors or latency spikes, which might indicate one EVC affecting
another EVC across the DUT.
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Key Measured Metrics
Statistic Relevance
Invalid Reflected Frames Key metric of the test case
Lost, Reordered, Duplicated, Late Show secondary buffering effects of reflected traffic
Real-Time Latency Shows how incorrect reflection of a packet back to the
originating CE-VAL can affect general traffic forwarding
across the EVC and other EVCs
Analysis
The user should not see reflected packets. If the user does see a reflected packet early on, it may
indicate a CAM insertion problem. If the reflected packet happens during a long duration test,
such as the random test, this may indicate a buffer overflow/broadcast problem. In addition,
when a reflected packet is observed, correlation to sequencing errors and spikes in real-time
latency may indicate a breakdown in isolation across top tagged customers (customer crosstalk).
Errors within the same customer but with variable inner tag traffic may indicate a problem in the
Q-in-Q queue in the DUT.
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MBH_002 Peak unicast traffic capacity across the EVC
Abstract
This test case determines the peak capacity of Ethernet Virtual Connections (EVCs) across
multiple circuits with best-effort traffic. This test case establishes EVC tunnels across the DUT,
filling each tunnel with traffic. The number of EVCs with best-effort traffic is increased until
failure occurs. The peak capacity of EVCs is an important attribute of a DUT which determines
how the DUT is provisioned in production networks. References: MEF 9, IEEE 802.1ad. For system
scalability testing.
Description
The EVC (Ethernet Virtual Circuit) is a key element of backhaul transport across a managed
Ethernet and IP core. An EVC defines a unique point-to-point or point-to-multipoint pathway
connecting multiple network UNI interfaces. Provider bridging standards permit customer traffic
to be tunneled over a provider network using 802.1ad. In 802.1ad, the customer traffic is
encapsulated inside of a provider Ethernet frame tagged with Q-in-Q VLAN traffic. The outer
VLAN Tag (EtherType: 0x88A8) is defined as the S-VLAN (Service Tag). This tag is local to the
provider and provides a quick switch mechanism to route packets effectively through the
provider network. The inner tag (EtherType: 0x8100) is called the C-VLAN and represents
customer private traffic. In addition, the CFI bit in the S-VLAN header represents Discard Eligible
(DE) frames similar to Frame Relay. This test case tests the ability of the DUT to scale the number
of point-to-point EVCs in the network by scaling both the S-VLAN and C-VLAN tags. Specifically,
scale is determined when neither the S-TAG DE bit is set by the DUT, nor the baseline
performance metrics vary past 0.5% of a single EVC.
Relevance
As networks grow, the demand for high performance scale of EVCs becomes more critical. In
addition, the demands of consistent performance under any scale become critical for key
network services.
Version
1.0
Test Category
Mobile Backhaul, Scalability test.
PASS
[ ] Performance [ ] Availability [ ] Security [x] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time.
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Topology
Test Procedure
1. Connect tester port A and tester port B to the DUT. Establish the link.
2. Configure the DUT for 4095 S-VLAN and 4095 C-VLAN Tags per S-VLAN.
3. Step 1 – Establish single EVC baseline.
a. On the tester, configure an single stream on S-VLAN:1,C-VLAN:1.
b. Establish 256 hosts per UNI. Create a partial mesh between hosts. Set the frame size to
random and the port load to line rate.
c. Clear all counters
d. Transmit traffic for 60 seconds.
e. Measure the Single EVC Max Jitter, EVC Forwarding Rate, Latency, and Sum of
Sequencing Errors.
f. Clear counters.
4. Step 2 – Measure the peak S-VLAN with single C-VLAN.
a. Loop the S-VLAN ID starting at 2 and ending at 4095.
i. Create an EVC between two UNIs on each tester port with an S-VLAN tag
representing the current loop value. Set the C-VLAN ID to 1.
ii. Create a partial mesh of hosts between each UNI for the EVC. Set the frame size to
random and the port load to 100%.
iii. While other EVCs are transmitting, begin traffic on the current EVC.
iv. Wait for the configured traffic duration.
v. Measure the max latency, max jitter, EVC FORWARDING rate, and sum of this EVC’s
sequencing errors.
1. A pass condition is defined as Max Latency and Max Jitter being no
more than 0.5% of the measured single EVC value, EVC Forwarding
Rate being no less than 0.5% of the measured single EVC value, no
sequencing errors and the DE bit not set high.
2. A fail condition is defined as any values outside of pass.
vi. If this iteration passes, loop to the next value. If it fails, record the current value -1
as the peak S-VLAN capacity.
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5. Step 3 – Measure the peak C-VLAN capacity.
a. Loop the S-VLAN ID starting at 2 and ending at the measured peak S-VLAN capacity.
i. Loop the C-VLAN ID starting at 2 and ending at 4095.
1. Create an EVC between two UNIs on each tester port with an S-VLAN
tag representing the current loop value. Set the C-VLAN ID to its
equivalent look value.
2. Create a partial mesh of hosts between each UNI for the EVC. Set the
frame size to random and the port load to 100%.
3. While other EVCs are transmitting, begin traffic on the current EVC.
4. Wait for the configured traffic duration.
5. Measure the max latency, max jitter, EVC forwarding rate, and sum of
this EVC’s sequencing errors.
a. A pass condition is defined as Max Latency and Max Jitter
being no more than 0.5% of the measured single EVC value,
EVC Forwarding Rate being no less than 0.5% of the
measured single EVC value, and no sequencing errors and the
DE bit not set high.
b. A fail condition is defined as any values outside of pass.
6. If this iteration passes, loop to the next value. If it fails, record the
current value -1 as the peak C-VLAN capacity.
Variables & Relevance
Variable Relevance
Tester Ports A & B Ports used to create and measure EVCs
Number of Hosts per EVC Number of hosts per EVC, default 256 hosts
Traffic Duration Time per Iteration, default 60 seconds
Desired Result
The DUT should be able to carry 4095 S-VLAN with 4095 C-VLAN EVC with max latency and jitter
measured at no worse than 0.5% of the measured single EVC value. EVC forwarding performance
should also be no less than 0.5% of the measured single EVC value. There should be no
sequencing errors and the DE bit should not be set high.
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Key Measured Metrics
Statistic Relevance
Single EVC Max Jitter Measured peak Jitter for a single EVC session
Sum of Single EVC Sequencing
Errors
Measured sum of sequencing errors for a single EVC
session
Single EVC Forwarding Rate Measured forwarding rate for a single EVC session
Single EVC Max Latency Peak latency on a single EVC
Measured EVC Max Jitter Per Iteration measured EVC max jitter
Measured EVC Sum of Sequencing
Errors
Per Iteration measured EVC sum of sequencing errors
Measured EVC Max Latency Per Iteration measured EVC maximum latency
Measured EVC Forwarding rate Per Iteration measured EVC forwarding rate
Peak S-VLAN Capacity Measured peak capacity of S-VLAN tags across the DUT
Peak C-VLAN Capacity Measured peak capacity of C-VLAN tags across the DUT
Analysis
In this test, the DUT address table is loaded in a random fashion and forwarding requests are
random based on the random frame size and per host load. As a result, maximum pressure is
placed on the DUT to add hosts to specific EVC (802.1ad) queues, forward across those queues,
and simultaneously add traffic and hosts while other EVC are in play. Compare the measured
number of S-VLAN and C-VLAN/S-VLAN ratios to the desired result to determine whether the
queue depths inside of the DUT are sized correctly and the code to process traffic is sufficient to
handle high performance EVC requests.
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MBH_003 Determine whether the DUT leaks traffic across EVCs
Abstract
This test determines whether the DUT leaks traffic across ports, EVC circuits, streams, or any
combination thereof. The test generates traffic across a range of frame sizes, loads, and multi-
burst conditions to ensure that all field scenarios are tested. Leaking traffic causes performance
problems, exposes secure information and disrupts services. By simultaneously testing port, EVC,
and service leakage, this test stresses single and multiple points of failure in the network in the
shortest time. By testing across different traffic patterns, this test stresses the DUT fabric for all
traffic patterns it will encounter in the field. References: MEF 9, IEEE 802.1ad. For functional
testing.
Description
Isolation of traffic per S-VLAN/C-VLAN combination is a critical part of an EVC service offering. In
this test, the tester simultaneously grows and collapses EVC tunnels while measuring whether
data from one tunnel leaks to another tunnel. Random frame sizes and rates are used to ensure
that the DUT is under peak stress.
Relevance
Leaked traffic from one EVC to another EVC represents a security and performance threat. By
verifying that the DUT does not leak traffic, the user will have higher confidence in the reliability
of the DUT even under high stress conditions.
Version
1.0
Test Category
Mobile backhaul, Acceptance test.
PASS
[ ] Performance [ ] Availability [x] Security [ ] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time.
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Topology
Test Procedure
1. Reserve tester ports A and B. Connect them to the DUT. Establish the link.
2. On the DUT, setup 4095 S-VLAN and 4095 C-VLAN/S-VLAN tunnels.
3. Clear all counters. All traffic in this test should have a frame fill of PRBS.
4. Begin the loop for the total number of iterations.
a. Setup the minimum number of EVC with the S-VLAN tag and C-VLAN tag to from one up
to the specified minimum. Set the number of hosts per UNI.
b. For each EVC, create a partial mesh of traffic per end point per EVC. Use random frame
sizes and set the port rate to line rate.
c. Start traffic.
d. Ramp up the number of EVC based on growth rate until the maximum EVC under load
value is reached without stopping existing traffic.
i. Additional EVCs should contain a partial mesh of endpoints and the specified
number of endpoints per UNI with random frame size.
e. Ramp down the number of EVC based on growth rate until the minimum number of EVC
under load value is reached without stopping existing traffic.
i. Additional EVCs should contain a partial mesh of endpoints and the specified
number of endpoints per UNI with random frame size.
5. Measure the PRBS error count.
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Variables & Relevance
Variable Relevance
Per Iteration Duration Time per iteration, default 60 seconds
Minimum EVC under Load Minimum number of EVCs with traffic, default 10
Maximum EVC under Load Maximum number of EVCs with traffic, default 4095
Growth rate Rate at which EVCs are ramped up and down, default 100
Total Number of Iterations Total number of Iterations in the test, default 100
Hosts per UNI Number of endpoints per UNI, default 256
Desired Result
The PRBS error count should be zero.
Key Measured Metrics
Statistic Relevance
PRBS Error Count Traffic Leakage
Analysis
In this test, stress is placed on the DUT by adding and removing EVCs and traffic. If the DUT leaks
traffic from one EVC to another EVC, the PRBS pattern is disturbed. Compare the iterations with
non-zero PRBS count errors to the desired result. This will give you information about which
combinations of S_LAN and C-VLAN caused leakage, and under what load and repetition count.
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MBH_004 Determine maximum EVC circuit capacity while
maintaining QoS profile
Abstract
This test determines whether the DUT maintains the QoS profile across EVC circuits while under
load. In this test, a QoS profile is established and applied to the S-Tag and C-Tag elements of the
EVC circuits. The circuit count is increased by incrementing the C-Tag count until the QoS profile
is no longer maintained. QoS is a key technology to insure service fidelity over EVC circuits.
Without verification of QoS capacity, the DUT may be over provisioned in the field and fail to
maintain service quality. References: MEF 9, IEEE 802.1ad, MEF 23. For functional testing.
Description
The DUTs ability to maintain QoS over EVC is a critical component to service delivery in the
network. The test case determines whether the following QoS model can be maintained by the
DUT under load.
Traffic
Class
Code
Point
Percent of
Traffic per
EVC
Traffic Pattern Minimum
Performance
Requirement
Video EF 50% MPEG2-TS – Using Built in
MPEG Clip
MOS-AV >4.8
Voice CS5 15% SIP (G.729) – 3 minute call
duration with WAV file
MOS >4.8
HTTP AF31 15% HTTP 1.1 / 64 byte GET Goodput TX/Goodput
RX=~.999
Routing AF11 3% OSPF Area 0 No OSPF Errors
Best Effort 00 17% Random Frame size and load Any
Relevance
The ability to maintain QoS over EVCs is a critical selling point of EVC circuits in the network.
Version
1.0
Test Category
Mobile backhaul, Acceptance test.
PASS
[ ] Performance [ ] Availability [ ] Security [x] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time
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Topology
Test Procedure
1. Reserve tester ports A and B. Connect them to the DUT. Establish the link.
2. On the DUT, setup 4095 S-VLAN and 4095 C-VLAN/S-VLAN tunnels and setup QoS according
to the table above. Set the age-out time to less than 50% of a single iteration.
3. Clear all counters.
4. Determine the peak S-VLAN and C-VLAN using MBH_003.
5. Setup the peak S-VLAN and C-VLAN/S-VLAN EVC tunnels.
6. Setup traffic patterns as described in the table above. Percentage of traffic is by session.
Stateful traffic should be utilized and marked by the appropriate DiffServ code point.
7. Begin the loop for the total number of iterations.
a. Start traffic.
b. Wait 50% of the iteration duration.
c. Measure the QoS performance metrics from the above table.
d. Disable 50% of all sessions without stopping the remainder of the traffic.
e. Wait 50% of the iteration duration.
f. Measure QoS performance metrics to the above table.
g. If both the full use and 50% use case conform to the above performance metrics, then
the iteration passes, else it fails.
8. Compare all iteration pass/fail results.
Variables & Relevance
Variable Relevance
Per Iteration Duration Time per iteration, default 60 seconds
Total Number of Iterations Total number of Iterations in the test, default 100
Desired Result
All iterations should pass.
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Key Measured Metrics
Statistic Relevance
Video MOS-AV Score Video performance
Voice G.729 MOS Score Voice MOS Score
HTTP Goodput Goodput of HTTP Score
OSPF Routing Errors Routing errors
Analysis
This test places real world voice, video, HTTP, OSPF, and best effort traffic to fill available
bandwidth across two EVC conditions, at full capacity EVC count, and 50% of peak. The test
reveals the effect on the DUT over a large number of iterations with QoS to determine whether
QoS is maintained with the addition of 50% more EVCs and their respective loads. If any iteration
fails then the traffic pattern, iteration count, and QoS profile give the user information about
which subsystems inside of the DUT are failing.
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MBH_005 Determine whether the DUT blocks invalid traffic over
the EVC
Abstract
This test determines whether the DUT properly blocks error from being transmitted across the
EVC tunnel. This test sets up a full mesh of traffic across the DUT, establishes EVC circuits, and
generates a mix of valid and invalid frames. The test determines simultaneously whether the DUT
forwards invalid traffic and whether processing a high rate of invalid traffic impairs the
forwarding of valid traffic. This test combines multiple tests into a single test. References: MEF 9,
IEEE 802.1ad. For functional testing.
Description
The DUT must be resilient to errored frames and not forward them across the core and EVC. In
this test, valid and errored frames are generated at variable rate and random frame size. The test
determines whether invalid traffic is forwarded.
Relevance
Invalid frames from one EVC to another EVC represent a performance threat. By verifying that
the DUT does not forward invalid frames, the user will have higher confidence in the reliability of
the DUT even under high stress conditions.
Version
1.0
Test Category
Mobile backhaul, Acceptance test.
PASS
[ ] Performance [x] Availability [x] Security [ ] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time.
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Topology
Test Procedure
1. Reserve tester ports A and B. Connect them to the DUT. Establish the link.
2. On the DUT, setup 4095 S-VLAN and 4095 C-VLAN/S-VLAN tunnels.
3. Clear all counters.
4. Begin the loop for the total number of iterations.
a. Setup the minimum number of EVCs with the S-VLAN tag and C-VLAN tag equal to one
up to the specified minimum. Set the number of hosts per UNI.
b. For each EVC, create a partial mesh of traffic per end point per EVC. Use random frame
sizes. Fifty percent of traffic should be valid frames and 50% should be invalid frames,
evenly distributed across the errored frame set.
c. Start traffic.
d. Ramp up the number of EVCs based on growth rate until the maximum EVC under load
value is reached without stopping existing traffic.
i. Additional EVCs should contain a partial mesh of endpoints and the specified
number of endpoints per UNI with random frame size. Fifty percent of traffic should
be valid frames and 50% should be invalid frames, evenly distributed across the
errored frame set.
e. Ramp down the number of EVCs based on the growth rate until the minimum number of
EVC under load value is reached without stopping existing traffic.
i. Additional EVCs should contain a partial mesh of endpoints and the specified
number of endpoints per UNI with random frame size. Fifty percent of traffic should
be valid frames and 50% should be invalid frames, evenly distributed across the
errored frame set.
5. Measure the sum of errored frames.
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Variables & Relevance
Variable Relevance
Per Iteration Duration Time per iteration, default 60 seconds
Minimum EVC under Load Minimum number of EVCs with traffic, default 10
Maximum EVC under Load Maximum number of EVCs with traffic, default 4095
Growth rate Rate at which EVCs are ramped up and down, default 100
Total Number of Iterations Total number of Iterations in the test, default 100
Hosts per UNI Number of endpoints per UNI, default 256
Set of Errored Frame Types Set of types of errors, default {CRC Error, Undersize, Over
Size, L4 CRC error, Jabber}
Desired Result
The sum of errored frame count should be zero.
Key Measured Metrics
Statistic Relevance
Sum of Errored Frame Counts Errors measured
Analysis
In this test, both valid and invalid traffic is ramped up and down numerous times while
measuring the real-time error frame count. When the user sees an errored frame, the quality of
the S-VLAN and C-VLANs, addressing, and ports allow the user to analyze the internal DUT invalid
frame filtering mechanisms.
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MBH_006 Measure accuracy of IEEE 1588v2 boundary clock timing
Abstract
This test case determines whether the DUT boundary clock replicates accurate timing to slave
clocks over a long duration under a load of traffic. The precision of the boundary clock and timer
variation is measured. Incorrect replication of timing as specified in IEEE 1588v2 by the boundary
clock can lead to incorrect network behavior, dropped handset communications, random errors,
and degraded bandwidth. References: IEEE 1588v2.
Description
IEEE 1588v2 timing precision, even under the load of non-deterministic traffic, is a key enabler
for moving traditional timing services from TDM-based networks to Ethernet services. With
timing, even small inaccuracies or lack of consistent and stable services can lead to severe mobile
handset outages, problems when handsets move from cell to cell, loss of data, and a reduced
customer experience. In addition, the diameter of the network is growing dramatically, requiring
high precision and predictability of accurate timing services over an arbitrary number of hops.
Because IEEE 1588v2 timing traffic coexists with other Ethernet services, such as EOAM and
IPv4/IPv6, this test determines errors in the precision of a clock signal across the DUT with a user-
defined number of slave clocks. In addition, the timing protocols compete with lower priority
bursty traffic. The precision is measured against the grand master clock and compared against
each neighbor slave clock to verify that 99.999% precession is maintained across the network.
Relevance
Incorrect variance in the IEEE 1588 clocking signal can lead to cell dropout, poor performance,
replication of network traffic, and incorrect cell tower identification.
Version
1.0
Test Category
Mobile backhaul, Acceptance test.
PASS
[x] Performance [x] Availability [ ] Security [ ] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time.
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Topology
Test Procedure
1. Reserve one tester port for the grand master clock, connect the port to the DUT, and bring
up the link.
2. Configure the connected port on the DUT to accept clocking from the emulated grand
master port and boundary the timing traffic to desired slave clock ports.
3. Reserve a desired number of slave clock domains, one per test port. Connect the ports to the
DUT. Configure the connected DUT ports as slave ports.
4. Establish the link on all ports.
5. Configure the emulated grand master port to start timing services. Configure the DiffServ
codepoint on timing traffic to AF31. Configure QoS on the DUT, and prioritize AF31 over all
traffic. Verify that the DUT forwards timing traffic.
6. On each emulated slave port, configure the desired number of emulated slave clocks.
7. Verify that each slave clock receives clocking form the DUT.
8. Create multiple full-mesh traffic across all test ports in the system.
a. DiffServ Codepoint = 0x00, Payload= PRBS Pattern.
b. Continuous.
c. Configure the desired number of host endpoints per port.
d. Set all ports to port priority mode.
e. Configure the following full mesh patterns.
f. Port priority 0.
i. Constant rate, 64 byte traffic at 50 % of line rate.
g. Port priority 1.
i. Burst (Burst=6, IFG=12), 1518 byte frame, at 20% of line rate.
h. Port priority 2.
i. Burst (Burst=100, IFG=50), 576 byte frame, at 28% of line rate
9. Wait the desired pre-measure time.
10. Calculate the clock error for each slave clock from the grand master clock.
11. Calculate the clock difference between each slave clock.
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12. Measure PRBS errors.
Variables & Relevance
Variable Relevance
Number of Emulated Slave Clock
Ports
Number of physical test ports used as slave timing ports,
default 5 ports
Number of Slave Clocks per Slave
port
Number of emulated slave clocks per port, default 100
Emulated Hosts Per Port Number of hosts per port to emulate, default 4096
Pre Measure Time Time to wait after starting clocking services before
measuring drift, default 4 hours
Desired Result
The clock drift from the grand master clock to each slave clock should be no more than 0.001%.
The difference between slave clocks should be 0. There should be no PRBS errors.
Key Measured Metrics
Statistic Relevance
Per Emulated Slave Clock Drift Drift due to congestions across the DUT
Total variance between emulated
slave clocks
Peak variance between all emulated slave clocks
PRBS Error Count Bit errors caused by the DUT
Analysis
If the drift of the slave clocks compared to each grand master clock connection though the DUT
boundary clock is greater than 0.001%, look for a pattern among the clocks that have more drift
and the clocks that have less. Does the drift happen in one step or is it progressive? Is there a
relationship between PRBS bit errors and clock drift?
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MBH_007 Determine IEEE 1588v2 slave clock capacity
Abstract
This test determines the ability of the DUT to support multiple IEEE 1588v2 slave clocks while
maintaining timing precision. This test case increases the number of slave clocks while measuring
the precision of timing compared to the grand master clock. Understanding how many slave
clocks a DUT can support while keeping precision is an important metric to refer to when
provisioning mechanism network. References: IEEE 1588v2.
Description
IEEE 1588v2 scale is a key element of a boundary clock DUT. This scale determines how many
boundary clocks and domains the network operator must deploy in the production network, with
the goal of maximizing the number of slave clocks without sacrificing precision or reliability.
Precision and reliability are key performance metrics that enable migration of timing services
from classic TDM circuits to managed Ethernet services.
The scale of the number of slave clocks the boundary clock can accurately replicate an IEEE
1588v2 timing signal from a grand master clock is determined by progressively adding clocks until
the precision of any clock in the system drops below the minimum drift of 0.001% . The test is
performed in the presence of multi-burst traffic to find a worst-case scenario for clock accuracy.
Relevance
Incorrect variance in the IEEE 1588 clocking signal can lead to cell dropout, poor performance,
replication of network traffic, and incorrect cell tower identification.
Version
1.0.
Test Category
Mobile backhaul, Scale test.
PASS
[x] Performance [ ] Availability [ ] Security [x] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time
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Topology
Test Procedure
1. Reserve one tester port for the grand master clock, connect the port to the DUT, bring up
the link.
2. Configure the connected port on the DUT to accept clocking from the emulated grand
master port and boundary the timing traffic to desired slave clock ports.
3. Reserve a second port and connect it to the DUT slave port. Configure the slave clocking
service on the DUT for this port.
4. Establish the link on all ports.
5. Configure the emulated grand master port to start timing services. Configure the DiffServ
codepoint on timing traffic to AF31. Configure QoS on the DUT, and prioritize AF31 over all
traffic. Verify that the DUT forwards timing traffic.
6. Create multiple full mesh traffic across all test ports in the system.
a. DiffServ Codepoint = 0x00, Payload= PRBS Pattern.
b. Continuous.
c. Configure the desired number of host endpoints per port.
d. Set all ports to port priority mode.
e. Configure the following full mesh patterns.
i. Port priority 0.
f. Constant rate, 64 byte traffic at 50 % of line rate.
i. Port priority 1.
g. Burst (Burst=6, IFG=12), 1518 byte frame, at 20% of line rate.
i. Port priority 2.
h. Burst (Burst=100, IFG=50), 576 byte frame, at 28% of line rate.
7. 7. Loop until any clock precision drifts more than 0.001% of the grand master clock or
when there are PRBS errors.
a. Add an emulated slave clock.
b. Wait the pre-measure time.
c. Verify that each slave clock receives clocking from the DUT.
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d. Measure the drift on all emulated clocks.
8. Record the current number of emulated slave clocks.
Variables & Relevance
Variable Relevance
Number of Slave Clocks per Slave
port
Number of emulated slave clocks per port, default 100
Emulated Hosts Per Port Number of hosts per port to emulate, default 4096
Pre Measure Time Time to wait after starting clocking services before
measuring drift, default 4 hours
Desired Result
The number of emulated slave clocks should match the designed peak number of slave clocks
supported on the DUT. There should be no PRBS errors.
Key Measured Metrics
Statistic Relevance
Peak Emulated Slave Clocks Maxim number of emulated slave clocks
PRBS Error Count Bit errors cause by the DUT
Analysis
If the drift of the slave clocks compared to each grand master clock connection though the DUT
boundary clock is greater than 0.001%, look for a pattern among the clocks that have more drift
and the clocks that have less. Does the drift happen in one step or is it progressive? Is there a
relationship between PRBS bit errors and clock drift?
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MBH_008 Scalability of IEEE 1588v2 clocks over VPLS
Abstract
This test determines the maximum size of the internal VPLS table while the DUT maintains timing
accuracy. In this test, the DUT VPLS and unicast BGP routing tables are incrementally filled until
timing precision decreases to below 99.999% accuracy as IEEE 1588v2 frames are transmitted
across VPLS. Backhauling IEEE 1588v2 traffic across VPLS tables is a key deployment strategy.
Incorrect timing can result in dropped calls and loss of bandwidth. References: IEEE 1588v2. For
scalability testing.
Description
IEEE 1588v2 performance tunneled inside of VPLS is a key performance metric of timing services
on a mobile backhaul device under test. A primary reason for migration to Ethernet services for
mobile timing is the ability to eliminate local TDM circuits and backhaul timing from more
centralized sources. This backhaul is generally achieved using VPLS/MPLS over BGP-4. Since the
DUT must simultaneously handle the VPLS and BGP RIB databases and maintain timing integrity,
events at the tunneling level can degrade performance while under load.
This test determines whether the size of the VPLS tunnel and BGP RIB affects the end-to-end
performance of IEEE 1588v2. This is achieved by tunneling IEEE 1588v2 timing over VPLS
between an emulated grand master clock and slave clock. BGP peers, emulated autonomous
systems, meaningful routes, and VPLS tunnels are expanded up to the limits of the device. The
timing performance is measured for excessive drift.
Relevance
IEEE 1588v2 timing must maintain performance, integrity, and accuracy even in the presence of
transport structures such as VPLS and BGP. Lack of integrity will lead to dropped calls, slow
performance, and device duplication in the network.
Version
1.0
Test Category
Mobile backhaul, Scale test.
PASS
[ ] Performance [ ] Availability [ ] Security [x] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time.
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Topology
Test Procedure
1. Reserve four tester ports. Connect the ports to the DUT and bring up the links.
2. Configure BGP on the DUT and set the AS to 100. Configure VPLS on the DUT and set the
DUT role as a P-Router.
3. Configure the DUT port connected to test port A to accept clocking from the grand master
clock emulated on tester port A. Peer BGP with the DUT.
4. Setup test port B as a slave clock. Peer BGP with the DUT.
5. On both test port A and B, emulate a P Router->PE Router->CE Router and clocking endpoint.
6. Begin clocking services.
7. Loop until known upper limits for AS count, route count and VPLS tunnel counter are
reached.
a. On tester port C and D, add to each a unique AS and peer both ports with the DUT.
b. Advertise desired maximum routes per AS.
c. Routes must have unique AS path, community sting and MED.
d. Emulate P Router->PE Router->CE Router on both ports.
e. Establish the maximum number of VPLS tunnels per AS pair.
f. Wait until routes converge.
g. Measure the clock drift on test port B.
h. When drift is greater than 0.001%, stop.
8. Record the number of BGP peers, advertised AS path count, routes, and VPLS tunnels.
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Variables & Relevance
Variable Relevance
Maximum BGP AS Maximum number of AS per DUT, default 10,000
Maximum Routes per AS Maximum number of routes per emulated AS, default
100000
Maximum VPLS Tunnels per AS
pair
Maximum number of tunnels per AS pair, default 4000
Desired Result
The BGP peers, advertised AS path count, routes, and VPLS tunnels counts should be the
maximum in each category that the DUT is designed to carry.
Key Measured Metrics
Statistic Relevance
Peak BGP Peers Total non-effecting BGP peers
Peak AS path count Total non-effecting AS paths
Peak Routes Total non-effecting routes
Peak VPLS Tunnels Maximum number of non-effecting VPLS tunnels
Analysis
Slave clock drift can be affected by routing and tunneling structures inside the DUT. If the count
of any metric is less than the design of the DUT, look for efficiencies in microcode, queue sizing,
and optimization inside the DUT.
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MBH_009 Duplicate clock identity detection in IEEE 1588v2
Abstract
This test determines whether the DUT can detect and avoid duplicate clock identities in the
network. In this test, the DUT clock identify string is replicated on emulated clocks on the test
interface to determine whether the DUT rejects the connection. Users are allowed to determine
the clock identity and thus allows for duplication of identities, which can lead to incorrect timing
behavior in the network. References: IEEE 1588v2.
Description
IEEE 1588v2 specifies that each device in the network have a unique clock identity. This test
determines whether the DUT disregards IEEE 1588 messages from a source duplicating its own
identity.
In this test, the emulation port attempts to peer with the DUT while replicating the Identity of
the DUT. The DUT should reject all invalid requests.
Relevance
Resilience to misconfiguration or Denial of Service attack is a key deployment benchmark for
production networks.
Version
1.0
Test Category
Mobile backhaul, Security test, Acceptance test.
PASS
[ ] Performance [x] Availability [x] Security [ ] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time.
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Topology
Test Procedure
1. Reserve tester port A and configure it as a grand master clock. Connect the port to the DUT
boundary clock and bring up the link.
2. Set the ID of the grand master clock to match the DUT.
3. Attempt to bring up the IEEE 1588v2 session and record the results.
4. On each slave port, configure the desired number of emulated slave clocks. Set the ID of the
slave clocks to match the DUT.
5. Attempt to bring up the IEEE 1588v2 session and record the results.
Variables & Relevance
Variable Relevance
Set of 1588v2 Slave Clocks Ports emulating slave clocks, default 4
Emulated Slave Clocks per Port Number of slave clocks emulated per port, default 100
DUT Clock ID ID of the DUT boundary clocks
Desired Result
Neither the grand master clock nor any slave clock should successfully peer with the DUT.
Key Measured Metrics
Statistic Relevance
Number of Established IEEE 1588
Sessions
Number of sessions established with conflicting Identity
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Analysis
The DUT should not peer with either class of emulated clock. If it does, look at the protocol logs
in the DUT and protocol details for a more detailed root cause. Try testing with more emulated
clocks, because session scale may affect the ability of the protocols stack to block invalid
sessions.
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MBH_010 Determine whether the 1588v2 grand master clock is
resilient to DDoS attacks
Abstract
This test determines whether the boundary clock can provide accurate timing to the network
while subject to distributed denial of service (DDoS) attacks. In this test, the boundary clock is
attacked while the timing protocol is bridged across the DUT. Protocol resilience is a critical part
of deployment in a production network. References: IEEE 1588v2. For security and acceptance
testing.
Description
IEEE 1588v2 security is a key element of the deployment in a production network. Because of the
potential for a single point of failure in the network, the user should test the behavior of the
boundary clock while under attack.
Relevance
Boundary clocks present a substantial security risk to the reliability of the network.
Version
1.0
Test Category
Mobile backhaul, Security test.
PASS
[ ] Performance [x] Availability [x] Security [ ] Scale
Required Tester Capabilities
The device under test must be able to add traffic live with the presence of existing traffic.
Further, the test equipment must be able to analyze traffic metrics in real-time
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Topology
Test Procedure
1. Reserve one tester port for the grand master clock, connect the port to the DUT, and bring
up the link.
2. Reserve one port as the Distributed Denial of Service (DDoS) attacking port. Configure line
rate traffic with a PDU of Ethernet>IP>UDP. Increment the UDP source and destination
ports. Connect this port to the boundary clock.
3. Start attack traffic toward the boundary clock.
4. Configure the connected port on the DUT to accept clocking from the emulated grand
master port and boundary the timing traffic to desired slave clock ports.
5. Reserve a desired number of slave clock domains, one per test port. Connect the ports to the
DUT. Configure the connected DUT ports as slave ports.
6. Establish links on all ports.
7. Configure the emulated grand master port to start timing services. Configure the DiffServ
codepoint on timing traffic to AF31. Configure QoS on the DUT, and prioritize AF31 over all
traffic. Verify that the DUT forwards timing traffic.
8. On each emulated slave port, configure the desired number of emulated slave clocks.
9. Verify that each slave clock receives clocking from the DUT.
10. Create multiple full mesh traffic across all test ports in the system.
a. DiffServ Codepoint = 0x00, Payload= PRBS Pattern.
b. Continuous.
c. Configure the desired number of host endpoints per port.
d. Set all ports to port priority mode.
e. Configure the following full mesh patterns.
i. Port priority 0.
f. Constant rate, 64 byte traffic at 50 % of line rate.
i. Port priority 1.
g. Burst (Burst=6, IFG=12), 1518 byte frame, at 20% of line rate.
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i. Port priority 2.
h. Burst (Burst=100, IFG=50), 576 byte frame, at 28% of line rate.
11. Wait the desired pre-measure time.
12. Calculate the clock error for each slave clock from the grand master clock.
13. Calculate the clock difference between each slave clock.
14. Measure any PRBS errors.
Variables & Relevance
Variable Relevance
Number of Emulated Slave Clock
Ports
Number of physical test ports used as slave timing ports,
default 5 ports
Number of Slave Clocks per Slave
port
Number of emulated slave clocks per port, default 100
Emulated Hosts Per Port Number of hosts per port to emulate, default 4096
Pre Measure Time Time to wait after starting clocking services before
measuring drift, default 4 hours
Desired Result
The clock drift from the grand master clock to each slave clock should be no more than 0.001%.
The difference between slave clocks should be 0. There should be no PRBS errors.
Key Measured Metrics
Statistic Relevance
Per Emulated Slave Clock Drift Drift due to congestions across the DUT
Total variance between emulated
slave clocks
Peak variance between all emulated slave clocks
PRBS Error Count Bit errors cause by the DUT
Analysis
If the drift of the slave clocks compared to each grand master clock connection though the DUT
boundary clock is greater than 0.001%, look for a pattern among the clocks that have more drift
and the clocks that have less. Does the drift happen in one step or is it progressive? Is there a
relationship between PRBS bit errors and clock drift? What happens when you change the PDU
type of the DDoS attack traffic to TCP?
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MBH_011 Measure 1588v2 boundary clock timing accuracy
when using GPS as the grand master timing source
Abstract
In this test case, the Spirent TestCenter chassis is connected to a GPS device from which itderives
timing. Spirent TestCenter port connect to the DUT, which acts as the boundary clock. One of the
Spirent TestCenter ports becomes the grand master, deriving its timing from the GPS source and
the second Spirent TestCenter port becomes the slave. This test case measures the current and
peak negative/positive offset values, thereby measuring the 1588v2 timing accuracy of the DUT
Description
This is a practical real-world scenario to prepare carriers and service providers for replacing
existing TDM-based circuits with the 1588v2 timing protocol, for a seamless transition to
IP/Ethernet based implementations for carrying backhaul traffic from mobile base stations to
core networks.
GPS is considered one of the most accurate timing source providers, with Stratum 1 Clock
accuracy. This timing synchronizes the base stations in a network so that the clock offset (or
differences) between the equipment within that network is within the tolerable limit so as not to
lose synchronization and eventually data – especially when operating at 100G speeds, where
even a split second synchronization loss could result in huge numbers of dropped bits.
Target Users
All NEMs and service providers
Target Device Under Test (DUT)
Core and Access Equipment
Reference
IEEE 1588v2
GPS clock accuracy
Relevance
This test case assesses the accuracy of GPS as the timing source for the grand master clock.
Version
1.0
Test Category
Testing Mobile Backhaul
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PASS
[x] Performance [] Availability [ ] Security [] Scale
Required Tester Capabilities
The tester must support:
1588v2 implementation
Spirent TestCenter chassis with the ability to connect GPS equipment and use it as the timing
source for the chassis
Ability to support GPS as the timing source for the 1588v2 protocol
Appropriate results reporting
Native graphing capabilities within the tester GUI
Topology Diagram
S p i r e n t
T e s t C e n t e r
P o r t 2 -
S l a v e C l o c k
E m u l a t i o n
S p i r e n t
T e s t C e n t e r P o r t
1 – G r a n d
M a s t e r C l o c k
E m u l a t i o n
G P S U n i t
D U T
B o u n d a r y C l o c k
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Test Procedure
1. Connect an approved GPS receiver physically to the Spirent TestCenter chassis.
a. Set the timing source for the chassis to GPS.
2. Configure the DUT to act a boundary clock and configure the parameters appropriately.
3. Configure 1588v2 protocol on Spirent TestCenter port 1 and 2.
a. Configure the PTP parameters on the emulated clocks such that port 1 becomes the
master/grandmaster and the DUT port connected to this port becomes the slave.
i. Select the timing source for the Spirent TestCenter emulated clock as GPS.
b. Configure the PTP parameters in such a way that port 2 becomes the slave clock and the
DUT Port connected to this port becomes the master.
4. Start the emulated clocks on the Spirent TestCenter ports and observe that the emulated
clock on port 1 becomes the master (grand master) and the port 2 becomes the SLAVE.
a. Also, verify that the DUT port connected to Spirent TestCenter port 1 becomes the slave
and the port connected to Spirent TestCenter port 2 becomes the master.
5. Under the Real-time Results, note the current offset deviation measurements, peak positive
and negative offset deviations and other results for the emulated clock on port 2 (which is
the slave). That is the drift between the clocks – from the grand master (on test port 1) to
the slave clock on test port 2 – as it passes through the DUT acting as the boundary clock.
a. Also, graph the offset deviation results to see the effect over time.
6. End of test case.
Control Variables & Relevance
Variable Relevance Default Value
Clock Accuracy Usually defined by the Timing Source you select
but as a Tester, we allow you to change it
1 microsecond
Grand Master Priority Determines who becomes the Grand Master Clock
in case of contention
128
Timing Source Timing Source selection for the Clock Emulation
which is going to be the Grand Master – we will be
using the GPS option for this test
Internal Oscillator
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Key Measured Metrics
Metric Relevance Metric Unit
Clock State To Determine whether the expected Emulated
clocks go into Master/Grand Master and Slave
State machines
Master/Slave
Current Offset
Deviation
The offset between the STC emulated Slave and
the Grand Master clocks as it passes through the
DUT which is acting as the Boundary Clock
Nanoseconds
Peak Positive and
Negative Offset
Deviation
The max positive and negative offset deviation –
to determine whether it is within the expected
range for that implementation
Nanoseconds
Desired Result
The emulated grand master clock should use the GPS as its timing source and derive the timing
from that. The emulated slave clock should calculate offset deviation readings between the
grand master clock and itself as it passes through the DUT, which acts as the boundary clock. The
state of the DUT port should also change according to the configuration defined above.
Analysis
This scenario uses the GPS unit as the timing source and the emulated grand master clock derives
its timing from that. The DUT acts as the boundary clock and hence forms a master/slave clock
relationship with the appropriate/respective test ports.
Capture the PTP message exchanges between the test ports and the DUT and verify that they
have accurate information.
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MBH_012 Measure 1588v2 boundary clock timing accuracy in
presence of impairments
Abstract
In this test case, test ports assess the DUT in the boundary clock mode by adding packet delay
variations and other impairments through ANUE 3500 Device connected in between the DUT and
the test ports.
Description
This is a practical real-world scenario to prepare carriers and service providers for replacing
existing TDM-based circuits with the 1588v2 timing protocol, for a seamless transition to
IP/Ethernet based implementations for carrying backhaul traffic from mobile base stations to
core networks.
No matter how well designed equipment device is, it will occasionally generate some kind of
errors/impairments when passing content. In the case of 1588v2, this problem becomes more
prominent as clocks lose synchronization and drift away in the presence of these
errors/impairments.
Hence, it becomes important to test these scenarios in the lab before the system is deployed.
Spirent’s ANUE test system is specifically built for emulating these scenarios – generating
impairment and PDVs - as defined in G.8261.
Target Users
All NEMs and service providers
Target Device Under Test (DUT)
Core and Access Equipment
Reference
IEEE 1588v2
G.8261
Relevance
This test case measures the 1588v2 clock accuracy in the presence of Impairments.
Version
1.0
Test Category
Testing Mobile Backhaul
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PASS
[x] Performance [] Availability [ ] Security [] Scale
Required Tester Capabilities
The tester mustsupport:
1588v2
Spirent TestCenter chassis
Ability to inject Impairments/PDVs with a device such as the Spirent ANUE 3500
Appropriate results reporting
Native graphing capabilities within the tester GUI
Topology Diagram
Test Procedure
1. Connect the equipment as shown in the topology diagram above.
2. Configure the 1588v2 protocol on the test ports in such a way that port 1 becomes the grand
master and port 2 becomes the slave for DUT2.
3. Configure both the DUTs to be a boundary clock.
4. Configure the Spirent ANUE 3500 to generate various impairments and measure
jitter/wander/MTIE/TDEV values.
a. In the presence of these impairments, observe the clock accuracy of DUT2 as measured
by port 2.
i. Under the Real-time Results, see the current offset deviation measurements, peak
positive and negative offset deviations and other results for the emulated clock on
port 2 (which is the slave). That is the drift between the clocks – from the grand
master (on test port 1) to the slave clock on test port 2 – as it passes through the
DUT and the ANUE device.
b. Graph the offset deviation results to see the effect over time.
5. End of test case.
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Control Variables & Relevance
Variable Relevance Default Value
Clock Accuracy Usually defined by the Timing Source you select but as a
Tester, we allow you to change it
1 microsecond
Impairments As defined by G.8261 profiles
PDV Packet Delay Variations introduced by the ANUE 3500
device
0
Key Measured Metrics
Matric Relevance Metric Unit
Clock State To Determine whether the expected Emulated clocks go
into Master/Grand Master and Slave State machines
Master/Slave
Current Offset
Deviation
The offset between the STC emulated Slave and the
Grand Master clocks as it passes through the DUT which
is acting as the Boundary Clock
Nanoseconds
Peak Positive and
Negative Offset
Deviation
The max positive and negative offset deviation – to
determine whether it is within the expected range for
that implementation
Nanoseconds
Jitter/Wander As measured by the ANUE 3500 device Nanoseconds
Desired Result
Wander measurements should be within the limits specified in G.8261. The clock accuracy
measured on test port 2 should be well within the expected range, in the presence of
impairments.
Analysis
The Spirent ANUE 3500 box has been designed to specifically support, in addition to other test
cases, this scenario to measure wander and introduce PDV, impairments and measure clock
accuracy in presence of impairments.
The clock accuracy – the offset deviation measurements - should decrease as the impairments
increase and should improve when they are removed. Also, the measured wander should be
within the limits as specified in G.8261.
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Appendix A – Telecommunications
Definitions
APPLICATION LOGIC. The computational aspects of an application, including a list of instructions that tells a
software application how to operate.
APPLICATION SERVICE PROVIDER (ASP). An ASP deploys hosts and manages access to a packaged application by
multiple parties from a centrally managed facility. The applications are delivered over networks on a
subscription basis. This delivery model speeds implementation, minimizes the expenses and risks incurred
across the application life cycle, and overcomes the chronic shortage of qualified technical personnel
available in-house.
APPLICATION MAINTENANCE OUTSOURCING PROVIDER. Manages a proprietary or packaged application from
either the customer's or the provider's site.
ASP INFRASTRUCTURE PROVIDER (AIP). A hosting provider that offers a full set of infrastructure services for
hosting online applications.
ATM. Asynchronous Transport Mode. An information transfer standard for routing high-speed, high-
bandwidth traffic such as real-time voice and video, as well as general data bits.
AVAILABILITY. The portion of time that a system can be used for productive work, expressed as a
percentage.
BACKBONE. A centralized high-speed network that interconnects smaller, independent networks.
BANDWIDTH. The number of bits of information that can move through a communications medium in a
given amount of time; the capacity of a telecommunications circuit/network to carry voice, data, and
video information. Typically measured in Kbps and Mbps. Bandwidth from public networks is typically
available to business and residential end-users in increments from 56 Kbps to 45 Mbps.
BIT ERROR RATE. The number of transmitted bits expected to be corrupted per second when two computers
have been communicating for a given length of time.
BURST INFORMATION RATE (BIR). The rate of information in bits per second that the customer may need over
and above the CIR. A burst is typically a short duration transmission that can relieve momentary
congestion in the LAN or provide additional throughput for interactive data applications.
BUSINESS ASP. Provides prepackaged application services in volume to the general business market,
typically targeting small to medium size enterprises.
BUSINESS-CRITICAL APPLICATION. The vital software needed to run a business, whether custom-written or
commercially packaged, such as accounting/finance, ERP, manufacturing, human resources and sales
databases.
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BUSINESS SERVICE PROVIDER. Provides online services aided by brick-and-mortar resources, such as payroll
processing and employee benefits administration, printing, distribution or maintenance services. The
category includes business process outsourcing (BPO) companies.
COMMERCE NETWORK PROVIDER. Commerce networks were traditionally proprietary value-added networks
(VANs) used for electronic data interchange (EDI) between companies. Today the category includes the
new generation of electronic purchasing and trading networks.
COMPETITIVE ACCESS PROVIDER (CAP). A telecommunications company that provides an alternative to a LEC
for local transport and special access telecommunications services.
CAPACITY. The ability for a network to provide sufficient transmitting capabilities among its available
transmission media, and respond to customer demand for communications transport, especially at peak
usage times.
CLIENT/DEVICE. Hardware that retrieves information from a server.
CLUSTERING. A group of independent systems working together as a single system. Clustering technology
allows groups of servers to access a single disk array containing applications and data.
COMPUTING UTILITY PROVIDER (CUP). A provider that delivers computing resources, such as storage, database
or systems management, on a pay-as-you-go basis.
CSU/DSU. Channel Server Unit/Digital Server Unit. A device used to terminate a telephone company
connection and prepare data for a router interface.
DATA MART. A subset of a data warehouse, intended for use by a single department or function.
DATA WAREHOUSE. A database containing copious amounts of information, organized to aid decision-
making in an organization. Data warehouses receive batch updates and are configured for fast online
queries to produce succinct summaries of data.
DEDICATED LINE. A point-to-point, hardwired connection between two service locations.
DEMARCATION LINE. The point at which the local operating company's responsibility for the local loop ends.
Beyond the demarcation point (also known as the network interface), the customer is responsible for
installing and maintaining all equipment and wiring.
DISCARD ELIGIBILITY (DE) BIT. Relevant in situations of high congestion, it indicates that the frame should be
discarded in preference to frames without the DE bit set. The DE bit may be set by the network or by the
user; and once set cannot be reset by the network.
DS-1 OR T-1. A data communication circuit capable of transmitting data at 1.5 Mbps. Currently in
widespread use by medium and large businesses for video, voice, and data applications.
DS-3 OR T-3. A data communications circuit capable of transmitting data at 45 Mbps. The equivalent data
capacity of 28 T-1s. Currently used only by businesses/institutions and carriers for high-end applications.
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ELECTRONIC DATA INTERCHANGE (EDI). The electronic communication of business transactions (orders,
confirmations, invoices etc.) of organizations with differing platforms. Third parties provide EDI services
that enable the connection of organizations with incompatible equipment.
ENTERPRISE ASP. An ASP that delivers a select range of high-end business applications, supported by a
significant degree of custom configuration and service.
ENTERPRISE RELATIONSHIP MANAGEMENT (ERM). Solutions that enable the enterprise to share comprehensive,
up-to-date customer, product, competitor and market information to achieve long-term customer
satisfaction, increased revenues, and higher profitability.
ENTERPRISE RESOURCE PLANNING (ERP). An information system or process integrating all manufacturing and
related applications for an entire enterprise. ERP systems permit organizations to manage resources
across the enterprise and completely integrate manufacturing systems.
ETHERNET. A local area network used to connect computers, printers, workstations, and other devices
within the same building. Ethernet operates over twisted wire and coaxial cable.
EXTENDED SUPERFRAME FORMAT. A T1 format that provides a method for easily retrieving diagnostics
information.
FAT CLIENT. A computer that includes an operating system, RAM, ROM, a powerful processor and a wide
range of installed applications that can execute either on the desktop or on the server to which it is
connected. Fat clients can operate in a server-based computing environment or in a stand-alone fashion.
FAULT TOLERANCE. A design method that incorporates redundant system elements to ensure continued
systems operation in the event of the failure of any individual element.
FDDI. Fiber Distributed Data Interface. A standard for transmitting data on optical-fiber cables at a rate of
about 100 Mbps.
FRAME. The basic logical unit in which bit-oriented data is transmitted. The frame consists of the data bits
surrounded by a flag at each end that indicates the beginning and end of the frame. A primary rate can be
thought of as an endless sequence of frames.
FRAME RELAY. A high-speed packet switching protocol popular in networks, including WANs, LANs, and
LAN-to-LAN connections across long distances.
GBPS. Gigabits per second, a measurement of data transmission speed expressed in billions of bits per
second.
HOSTED OUTSOURCING. Complete outsourcing of a company's information technology applications and
associated hardware systems to an ASP.
HOSTING PROVIDER. Provider who operates data center facilities for general-purpose server hosting and
collocation.
INFRASTRUCTURE ISV. And independent software vendor that develops infrastructure software to support
the hosting and online delivery of applications.
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INTEGRATED SERVICES DIGITAL NETWORK (ISDN). An information transfer standard for transmitting digital voice
and data over telephone lines at speeds up to 128 Kbps.
INTEGRATION. Equipment, systems, or subsystem integration, assembling equipment or networks with a
specific function or task. Integration is combining equipment/systems with a common objective, easy
monitoring and/or executing commands. It takes three disciplines to execute integration: 1) hardware, 2)
software, and 3) connectivity – transmission media (data link layer), interfacing components. All three
aspects of integration have to be understood to make two or more pieces of equipment or subsystems
support the common objective.
INTER-EXCHANGE CARRIER (IXC). A telecommunications company that provides telecommunication services
between local exchanges on an interstate or intrastate basis.
INTERNET SERVICE PROVIDER (ISP). A company that provides access to the Internet for users and businesses.
INDEPENDENT SOFTWARE VENDOR (ISV). A company that is not a part of a computer systems manufacturer
that develops software applications.
INTERNETWORKING. Sharing data and resources from one network to another.
IT SERVICE PROVIDER. Traditional IT services businesses, including IT outsourcers, systems integrators, IT
consultancies and value added resellers.
KILOBITS PER SECOND (KBPS). A data transmission rate of 1,000 bits per second.
LEASED LINE. A telecommunications line dedicated to a particular customer along predetermined routers.
LOCAL ACCESS TRANSPORT AREA (LATA). One of approximately 164 geographical areas within which local
operating companies connect all local calls and route all long-distance calls to the customer's inter-
exchange carrier.
LOCAL EXCHANGE CARRIER (LEC). A telecommunications company that provides telecommunication services
in a defined geographic area.
LOCAL LOOP. The wires that connect an individual subscriber's telephone or data connection to the
telephone company central office or other local terminating point.
LOCAL/REGIONAL ASP. A company that delivers a range of application services, and often the complete
computing needs, of smaller businesses in their local geographic area.
MEGABITS PER SECOND (MBPS). 1,024 kilobits per second.
METAFRAME. The world's first server-based computing software for Microsoft Windows NT 4.0 Server,
Terminal Server Edition multi-user software (co-developed by Citrix).
MODEM. A device for converting digital signals to analog and vice versa, for data transmission over an
analog telephone line.
MULTIPLEXING. The combining of multiple data channels onto a single transmission medium. Sharing a
circuit - normally dedicated to a single user - between multiple users.
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MULTI-USER. The ability for multiple concurrent users to log on and run applications on a single server.
NET-BASED ISV. An ISV whose main business is developing software for Internet-based application services.
This includes vendors who deliver their own applications online, either directly to users or via other
service providers.
NETWORK ACCESS POINT (NAP). A location where ISPs exchange traffic.
NETWORK COMPUTER (NC). A thin-client hardware device that executes applications locally by downloading
them from the network. NCs adhere to a specification jointly developed by Sun, IBM, Oracle, Apple and
Netscape. They typically run Java applets within a Java browser, or Java applications within the Java
Virtual Machine.
NETWORK COMPUTING ARCHITECTURE. A computing architecture in which components are dynamically
downloaded from the network onto the client device for execution by the client. The Java programming
language is at the core of network computing.
ONLINE ANALYTICAL PROCESSING (OLAP). Software that enables decision support via rapid queries to large
databases that store corporate data in multidimensional hierarchies and views.
OPERATIONAL RESOURCE PROVIDER. Operational resources are external business services that an ASP might
use as part of its own infrastructure, such as helpdesk, technical support, financing, or billing and payment
collection.
OUTSOURCING. The transfer of components or large segments of an organization's internal IT infrastructure,
staff, processes or applications to an external resource such as an ASP.
PACKAGED SOFTWARE APPLICATION. A computer program developed for sale to consumers or businesses,
generally designed to appeal to more than a single customer. While some tailoring of the program may be
possible, it is not intended to be custom-designed for each user or organization.
PACKET. A bundle of data organized for transmission, containing control information (destination, length,
origin, etc.), the data itself, and error detection and correction bits.
PACKET SWITCHING. A network in which messages are transmitted as packets over any available route rather
than as sequential messages over circuit-switched or dedicated facilities.
PEERING. The commercial practice under which nationwide ISPs exchange traffic without the payment of
settlement charges.
PERFORMANCE. A major factor in determining the overall productivity of a system, performance is primarily
tied to availability, throughput and response time.
PERMANENT VIRTUAL CIRCUIT (PVC). A PVC connects the customer's port connections, nodes, locations, and
branches. All customer ports can be connected, resembling a mesh, but PVCs usually run between the
host and branch locations.
POINT OF PRESENCE (POP). A telecommunications facility through which the company provides local
connectivity to its customers.
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PORTAL. A company whose primary business is operating a Web destination site, hosting content and
applications for access via the Web.
REMOTE ACCESS. Connection of a remote computing device via communications lines such as ordinary
phone lines or wide area networks to access distant network applications and information.
REMOTE PRESENTATION SERVICES PROTOCOL. A set of rules and procedures for exchanging data between
computers on a network, enabling the user interface, keystrokes, and mouse movements to be
transferred between a server and client.
RESELLER/VAR. An intermediary between software and hardware producers and end users. Resellers
frequently add value (thus Value-Added Reseller) by performing consulting, system integration and
product enhancement.
ROUTER. A communications device between networks that determines the best path for optimal
performance. Routers are used in complex networks of networks such as enterprise-wide networks and
the Internet.
SCALABILITY. The ability to expand the number of users or increase the capabilities of a computing solution
without making major changes to the systems or application software.
SERVER. The computer on a local area network that often acts as a data and application repository and that
controls an application's access to workstations, printers and other parts of the network.
SERVER-BASED COMPUTING. A server-based approach to delivering business-critical applications to end-user
devices, whereby an application's logic executes on the server and only the user interface is transmitted
across a network to the client. Benefits include single-point management, universal application access,
bandwidth-independent performance, and improved security for business applications.
SINGLE-POINT CONTROL. One of the benefits of the ASP model, single-point control helps reduce the total
cost of application ownership by enabling widely used applications and data to be deployed, managed
and supported at one location. Single-point control enables application installations, updates and
additions to be made once, on the server, which are then instantly available to users anywhere.
SPECIALIST ASP. Provide applications which serve a specific professional or business activity, such as
customer relationship management, human resources or Web site services.
SYSTEMS MANUFACTURER. Manufacturer of servers, networking and client devices.
TELECOMS PROVIDER. Traditional and new-age telecommunications network providers (telcos).
THIN CLIENT. A low-cost computing device that accesses applications and and/or data from a central server
over a network. Categories of thin clients include Windows-Based Terminals (WBT, which comprise the
largest segment), X-Terminals, and Network Computers (NC).
TOTAL COST OF OWNERSHIP (TCO). Model that helps IT professionals understand and manage the budgeted
(direct) and unbudgeted (indirect) costs incurred for acquiring, maintaining and using an application or a
computing system. TCO normally includes training, upgrades, and administration as well as the purchase
price. Lowering TCO through single-point control is a key benefit of server-based computing.
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TOTAL SECURITY ARCHITECTURE (TSA). A comprehensive, end-to-end architecture that protects the network.
TRANSMISSION CONTROL PROTOCOL/INTERNET PROTOCOL (TCP/IP). A suite of network protocols that allow
computers with different architectures and operating system software to communicate over the Internet.
USER INTERFACE. The part of an application that the end user sees on the screen and works with to operate
the application, such as menus, forms and buttons.
VERTICAL MARKET ASP. Provides solutions tailored to the needs of a specific industry, such as the healthcare
industry.
VIRTUAL PRIVATE NETWORK (VPN). A secure, encrypted private connection across a cloud network, such as
the Internet.
WEB HOSTING. Placing a consumer's or organization's web page or web site on a server that can be
accessed via the Internet.
WIDE AREA NETWORK. Local area networks linked together across a large geographic area.
WINDOWS-BASED TERMINAL (WBT). Thin clients with the lowest cost of ownership, as there are no local
applications running on the device. Standards are based on Microsoft's WBT specification developed in
conjunction with Wyse Technology, NCD, and other thin client companies.
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Appendix B – Layer 2 802.1q CoS
The following tables represent best practices for Layer 2 VLAN / Q-in-Q CoS. Each row relates the
appropriate metric to measured minimum acceptable for its respective traffic class.
VLAN 802.1p CoS / Q-in-Q Priority
802.1 PRI
CoS
Min. RX / TX
Bandwidth
Ratio
Max
Jitter
(uSec)
Max
Latency
(uSec)
Max
Loss
(Frames)
Max
Duplicate
(Frames)
Max
Reordered
(Frames)
Max
Late
(Frames)
7 1 0 >=1 0 0 0 0
6 1 0 2 0 0 0 0
5 .99 1 2 0 0 0 0
4 .98 1 3 0 0 0 0
3 .95 2 5 0 1 1 1
2 .90 3 5 1 1 1 1
1 .85 5 10 1 2 2 2
0 ANY ANY ANY ANY ANY ANY ANY
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Appendix C – RFC 2474 Layer 3 QoS
The following tables represent best practices for Layer 2 VLAN / Q-in-Q CoS. Each row relates the
appropriate metric to measured minimum acceptable for its respective traffic class.
IPv4 / IPv6 DiffServ
Codepoint Max Jitter
(uSec)
Max
Latency
(uSec)
Max Loss
(Frames)
Max
Duplicate
(Frames)
Max
Reordered
(Frames)
Max Late
(Frames)
EF 0 >=1 0 0 0 0
AF31 0 2 0 0 0 0
AF21 2 5 0 1 1 1
AF11 3 5 1 1 1 1
BE ANY ANY ANY ANY ANY ANY
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Appendix D – RFC 2474 Layer 3 QoS
Definitions
The following table represents the definitions of each DiffServ Codepoint possibility.
DSCP Value DF Code
Point
Equivalent IP
Precedent
Description
000 000 00 BE 000 - Routine Best Effort, Unclassified Quality
001 010 10 AF11 001 - Priority High-Throughput Transactions with high loss
sensitivity
001 100 12 AF12 001 - Priority High-Throughput Transactions with some loss
sensitivity
001 110 14 AF13 001 - Priority High-Throughput Transactions with loss
resiliency
001 010 18 AF21 001 - Immediate Low-Latency Transactions with high loss
sensitivity
010 100 20 AF22 001 - Immediate Low-Latency Transactions with some loss
sensitivity
010 119 22 AF23 001 - Immediate Low-Latency Transaction with loss resiliency
011 010 26 AF31 011 - Flash Broadcast Media with high loss sensitivity
011 110 28 AF32 011 - Flash Broadcast Media with some loss sensitivity
011 110 30 AF33 001 - Flash Broadcast Media with loss resiliency
100 010 34 AF41 100 – Flash Override Live Media with high loss sensitivity
100 110 36 AF42 100 – Flash Override Live Media with some loss sensitivity
100 110 38 AF43 100 – Flash Override Live Media with loss resiliency
101 110 46 EF 101 – Critical Mission Critical Transactions or VoIP
