RATTINA PRABA ANNAMALAI MADHAN PANCHAKSHARAM … · MEF 6.1, the Ethernet Service Specification...
Transcript of RATTINA PRABA ANNAMALAI MADHAN PANCHAKSHARAM … · MEF 6.1, the Ethernet Service Specification...
RATTINA PRABA ANNAMALAI MADHAN PANCHAKSHARAM Senior Manager Engineering, Carrier Ethernet Products Product Manager, Carrier Ethernet Products
© 2002-2013 Veryx Technologies |1
Introduction to Carrier Ethernet
Ethernet has long been the de-facto standard in local area networks (LANs). Its simplicity and widespread
use have made it a very popular technology in data communications networks. Evolving from a pure LAN,
Ethernet is now being adopted in Metro Area Networks (MANs) and Wide Area Networks (WANs).
Carrier Ethernet (CE) enhances legacy Ethernet by providing new capabilities and enriched technologies
for functioning in carrier networks and delivering Ethernet services over the WAN. The Metro Ethernet
Forum (MEF) develops CE technical specifications and implementation agreements to promote
interoperability and deployment of Carrier Ethernet worldwide. Figure 1 and Figure 2 below explain a
sample application of CE in Mobile backhaul and Enterprise connectivity.
According to the latest Analyst reports, some of the key drivers for the growth of Ethernet market are IP
migration, evolution of border-less enterprise, and convergence.
Figure 1: Carrier Ethernet in Mobile Backhaul
Figure 2: Carrier Ethernet in Enterprise Connectivity
Evolution of CE 2.0
MEF has defined the concept of Carrier Ethernet generations to differentiate the new features that are
now being supported and thus accelerate global adoption of Ethernet services. MEF CE generations
clearly communicate the Carrier Ethernet evolution, the value it brings to the market and provides
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directional roadmap for the industry.
Carrier Ethernet 1.0 (CE 1.0) encompassed the three standardized Ethernet services namely Ethernet
Private Line, Ethernet Virtual Private Line and Ethernet Private LAN as defined by MEF 6.
CE 2.0 builds on the specifications developed and approved over several years by MEF. CE 2.0
encompasses more than twice the number of specifications than were in CE 1.0. CE 2.0 greatly expands
from three services in first generation of CE to eight services. MEF 6.1, the Ethernet Service Specification
defines Port and VLAN-based E-Line, E-LAN and E-Tree services, while MEF 33, the Ethernet Access Service
Specification defines the E-Access services (Access EPL and Access EVPL).
Further, CE 2.0 carries newly standardized and powerful service features of Multi-CoS with Performance
Objectives, Interconnect and Manageability, through the integrated delivery of MEF Service Attributes
(MEF 10.2, 10.2.1, 26.1), Implementation Agreements (MEF 13, 20, 23.1) and Management Specifications
(MEF 7.1, 16, 17, 30, 31).
Carrier Ethernet 2.0 Retail Service types
CE 2.0 defines six service types for Retail Subscribers namely: E-Line, E-LAN and E-Tree services which are
further classified into Port-based and VLAN-based service types. Port-based service types do not support
service multiplexing at the UNI while VLAN-based service types support service multiplexing i.e., multiple
services at an UNI.
Table 1: Ethernet Subscriber Service types
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Carrier Ethernet 2.0 Wholesale Service types
CE 2.0 defines Access Ethernet Private Line and Access Ethernet Virtual Private Line to standardize
interconnects while deploying wholesale services. Figure 3 explains E-Access in the wholesale scenario.
Figure 3: Carrier Ethernet in Wholesale scenario
Table 2: Ethernet Access Service Types
CE 2.0 Verification Challenges
While CE 2.0 can offer substantial benefits to the subscribers and the service providers, it requires
considerable effort from equipment manufacturers and service providers to ensure that the devices and
services respectively are compliant to MEF CE 2.0. Veryx has identified the following top 7 challenges in
verification of services and equipment for compliance to CE 2.0 from a tester’s perspective:
Substantial increase in scope of verification for CE 2.0
Multi-CoS Verification
Continuous Performance measurement for different frame sizes
Bandwidth Profile Verification
Verification of Handling of Different Frames
Verification of Multiple EVCs per UNI support
Measuring behavior in real-time distributed deployment scenarios
These challenges necessitate considerable time and effort towards equipment and service verification for
MEF CE 2.0 compliance and thereby significantly delaying the ‘time-to-market’.
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1. Substantial increase in scope of verification for CE 2.0
For compliance verification, while CE 1.0 has around 250 test cases, CE 2.0 now has 680 test cases.
Significant time and effort would need to be spent by service providers and equipment vendors for their
CE 2.0 readiness, due to:
Additional feature coverage for each of the existing service types as well as addition of new service
types with totally new capabilities.
Negative scenario verification for each of the functionalities
For ease of verification, MEF has devised the test cases grouping based on the services and thus number
of test cases to be verified is based on the device capabilities and the services offered.
Figure 4: CE 2.0 Increase in Scope
2. Multi-CoS Verification
Multi-CoS is at the heart of what customers care about most: service level agreements (SLAs). Meeting
MEF specs for Multi-CoS is one of the most challenging parts of CE 2.0 certification. While Multi-CoS is not
a new technology defined by MEF, the key benefit MEF brings is the standardization of the classes of
service parameters for various applications
Multi-CoS is the capability to support three standardized Class of Service Labels, H, M, and L (High,
Medium and Low) and provide consistent performance and measurability across single MEN or multiple
interconnected MENs administered by different operators.
The sets of performance objectives and associated parameters for each CoS label are called Performance
Tiers (PT). Each CoS Label identifies four PTs and each PT is associated with specific performance
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objectives for performance attributes such as Mean Frame Delay (MFD), Frame Delay (FD), Frame Delay
Range (FDR), Inter Frame Delay Variation (IFDV) and Frame Loss Ratio (FLR) to support specific application
traffic such as voice, data and video. CE 2.0 Specifications recommended for a wide variety of application
types such as VoIP, IPTV Data, etc., and many of which would be used concurrently by end-users.
Based on typical distances between end points, four PTs are defined and CPO is defined for each of these
performance tiers. Table 3 lists a sample for performance tiers, associated distance and maximum frame
delay for each of the performance tiers.
Table 3: Performance Tier Classifications
Performance Tier Performance Tier Name Distance Maximum Frame Delay
PT1 Metro < 250 km 10 ms
PT2 Regional < 1200 km 25 ms
PT3 National < 7000 km 77 ms
PT4 Global < 27500 km 230 ms
The Table 4 gives a snapshot of Performance Tier and CoS-Label based verifications applicable for various
applications. CPOs corresponding to each of the CoS-Label and Performance Tiers are defined in the CE
2.0 specifications and needs to be verified as part of CE 2.0 conformance.
Table 4: Mapping of Cos-Label and Performance Tier for Applications
CoS Label H M L
Performance Tier 1 2 3 4 1 2 3 4 1 2 3 4
VoIP
VoIP & videoconf signaling
Videoconf data
IPTV data
IPTV control
Streaming media
Interactive gaming
SANs synch replication
SANs asynch replication
Network attached storage
Text & graphics terminals
T.38 fax over IP
Database hot standby
Database WAN replication
Database client/server
Financial/Trading
CCTV
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CoS Label H M L
Performance Tier 1 2 3 4 1 2 3 4 1 2 3 4
Telepresence
Circuit Emulation
Mobile BH H
Mobile BH M
Mobile BH L
For a given EVC, a particular PT may be applied and a different PT may apply to an OVC that is part of the
EVC. Different PTs have different CoS Performance Objectives (CPOs) specified in the CE 2.0 Specifications.
Verification for CE 2.0 requires that each service be thus thoroughly tested for the following CoS
Performance Objectives:
Combination of application specific mapping into High, Medium or Low (H, M, L) CoS-Labels
Service performance objectives determined by Performance tiers based on the geographical span of
the connectivity
Service treatments for various applications that might implement PCP or DEI or DSCP based class of
service mapping.
Traffic simulation for these ranges of scenarios and implementations requires a comprehensive test
strategy and test expertize to generate and accurately verify these scenarios. Verification of equipments
for CE 2.0 would involve verifying almost all of these scenarios, since the network equipments in general
are not built to specific applications. Also, manual execution of the test plan would be time consuming.
3. Continuous Performance Measurement for different Frame sizes
The performance attribute measurement for each of the service would require ensuring conformance to
SLAs over extended durations to account for:
Varying usage patterns during different time periods in a day
Dependencies on the usage pattern of different users
Consistency and stability of the circuit over a period of time
CE 2.0 ensures consistent service delivery and enforces verification of performance over extended periods
while accounting for service SLAs at the committed traffic rates including burst configurations.
This kind of measurement requires scalable test generation equipment with capabilities to capture the
traffic behavior over the extended period and provide appropriate reporting with logs to analyze the
behavior for trouble shooting.
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4. Bandwidth Profile Verification
CE 2.0 defines bandwidth profile attributes (CIR/EIR & CBS/EBS) at multiple levels such as UNI, EVC and
CoS along with combination of these levels put together. Table 5 and Table 6 give a quick snapshot of
varying levels of bandwidth profile verifications that are applicable for each of the service types.
Table 5: Bandwidth profile verifications for Ethernet Subscriber Services
Bandwidth Profile Service Attributes EPL EVPL EP-LAN EVP-LAN EP-Tree EVP-Tree
Ingress Bandwidth Profile – CIR/CBS Enforcement
Egress Bandwidth Profile – CIR Enforcement
Ingress Bandwidth Profile – EIR/EBS Enforcement
Ingress Bandwidth per UNI
Egress Bandwidth per UNI
Ingress Bandwidth per EVC
Egress Bandwidth per EVC
Ingress Bandwidth per CoS – PCP/DSCP/L2CP
Egress Bandwidth per CoS – PCP/DSCP/L2CP
Multiple Ingress Bandwidth per UNI
Table 6: Bandwidth profile verifications for Ethernet Access Services
Bandwidth Profile Service Attributes Access EPL Access EPL Access EVPL Access EVPL
UNI to ENNI ENNI to UNI UNI to ENNI ENNI to UNI
Ingress Bandwidth Profile – CIR/CBS Enforcement
Egress Bandwidth Profile – CIR Enforcement
Additionally, the verification of bandwidth profiles are also done in various ranges of CIR enforcements
based Interface speed for each of the Class of Service. For example, a 100 Mbps interface speed at ENNI
interface would require verification for CIR enforcements at 3 Mbps, 9 Mbps, 30 Mbps and 90 Mbps for
each of the H, L and M Service Classes.
Testing for all these enforcements require creation of multiple test flows for the required granularity and
rates and verification of performance behavior for each of these test flows for the prescribed test
duration. This time consuming exercise also has a high probability of oversight errors in verifying the
accurate enforcements of the bandwidths. To avoid these oversight errors, some level of script
development is required to record and compare the results against the expected.
Most importantly, CE 2.0 enforces efficient network usage by ensuring that these SLAs are met without
the network being overprovisioned. Testing and troubleshooting under boundary conditions require
comprehensive understanding of the burst configurations and implementations of the network devices
used to deliver the service.
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5. Verification of Handling of Different Frames
CE 2.0 compliance verification includes tests for service frames, control frames and invalid frames
handling.
Valid Unicast, Multicast, Broadcast and Unknown destination MAC Service frames need to be handled
as per the specified test procedure and this testing need to be performed for both tagged and
untagged frames.
Service control frames such as L2CP and SOAM frame handling need to be varied and some of the
frames need to be tunneled or discarded while others to be responded. The action is based on the
type of the control frames and involved service type, as defined in the specifications.
Handling of Invalid FCS (Frame Check Sequence) frames need to be verified as part of the attributes
testing.
Figure 5: CE 2.0 Frame Handling Verifications
Verification using the test data and testing for the multiple combinations is a challenge and involves
detailed testing and verification strategy.
6. Verification of Multiple EVCs per UNI support
A single UNI is multiplexed to support with more than one EVC in multiplexed services as EVPL, EVP-LAN
and EVP-Tree. It is mandatory that if service multiplexing is supported in the UNI then the maximum
number of EVCs supported per UNI is based on its speed and as per Table 7 below.
Table 7: Maximum Number of EVCs per UNI
UNI Speed Maximum number of EVCs to be supported
Greater than or equal to 10 Gbps 512
Greater than or equal to 1 Gbps 64
Less than 1 Gbps 8
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Verification of this capability involves the configuration of the specified of number of EVCs at the UNI and
to ensure that valid service frames offered at this UNI for each of the EVCs are delivered properly. This
functionality verification is difficult to perform and involves additional effort to simulate multiple service
frames flows and verification of each of the flows to ensure that the service frames are received properly
without instances of duplicate or missing frames.
Figure 6: Service Multiplexing - Maximum EVC Support
7. Measuring behavior in real-time distributed deployment scenarios
For service provider testing, it is important that the measurement of service performance parameters
such as Frame delay (FD), Frame delay variation (FDV) and Frame loss ratio (FLR) are done in a distributed
environment on real circuits. To simulate the behavior in the real time, these parameters need to be
verified with a combination of:
Varying traffic conditions such as continuous traffic and burst traffic
Varying combinations of burst densities
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Veryx offering for CE 2.0 conformance testing
Veryx ATTEST MEF CE2 test solution helps Carrier Ethernet equipment vendors and service providers
overcome these key challenges and thereby accelerate the readiness of Carrier Ethernet equipment and
services for MEF CE 2.0 compliance. Veryx ATTEST MEF CE2 test solution is offered in two flavors namely:
ATTEST-CTS MEF CE2, suitable for testing in lab by network equipment manufacturers
ATTEST-CTS MEF CE2 FT, suitable for testing in the field by service providers.
Figure 7: Sample test topology for Lab test using ATTEST
Veryx ATTEST-CTS CE2 test solution is aligned completely with MEF Carrier Ethernet 2.0 test cases and is
functionally grouped according to related Ethernet services attributes, performance attributes, Ingress
bandwidth profile and Egress bandwidth profile attributes that they verify. The solution is highly
automated and relies on ATTEST -- a powerful test framework that requires minimal setup time and
enables efficient use of time and resources.
Using ATTEST-CTS MEF CE2 FT service providers can verify their circuits from a central office, by deploying
probes at suitable points across geographical locations. Figure 8 shows a sample test topology used for
real-time distributed testing using Veryx ATTEST controller and probes.
Figure 8: Sample topology for distributed testing using ATTEST
Acronym Definition Acronym Definition
BH Backhaul FD Frame Delay
CBS Committed Burst Size FDR Frame Delay Range
CCTV Closed Circuit Television IP Internet Protocol
CE Carrier Ethernet IPTV Internet Protocol Television
CIR Committed Information Rate IFDV Inter Frame Delay Variation
CoS Class of Service LAN Local Area Network
CPO CoS Performance Objective L2CP Layer 2 Control Protocol
DEI Drop Eligibility Indicator MAC Media Access Control
DSCP Differentiated Services Code Point MFD Mean Frame Delay
EBS Expected Burst Size MAN Metro Area Network
EIR Expected Information Rate MEF Metro Ethernet Forum
E-Access Ethernet Access PT Performance Tier
ENNI External Network to Network Interface PCP Priority Code Point
EPL Ethernet Private Line Service RAN Radio Access Network
EP-LAN Ethernet Private LAN Service RNC Radio Network Controller
EP-Tree Ethernet Private Tree SAN Storage Area Network
EVC Ethernet Virtual Circuit SOAM Service Operations Administration and Maintenance
EVPL Ethernet Virtual Private Line Service SLA Service Level Agreement
EVP-LAN Ethernet Virtual Private LAN Service UNI User Network Interface
EVP-Tree Ethernet Virtual Private Tree VoIP Voice over Internet Protocol
FCS Frame Check Sequence VLAN Virtual Local Area Network
FT Field Test WAN Wide Area Network
FLR Frame Loss Ratio
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