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


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


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’.


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


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


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.


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.


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


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


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

www.veryxtech.com [email protected]

Veryx Technologies (www.veryxtech.com) is an innovative enterprise providing solutions that enhance product quality and testing efficiency. Veryx offers flexible, cost-effective products that enhance the Service Assurance capabilities of Ethernet Service Providers. Leading equipment vendors, rely on the ATTEST range of products for testing applications in Access, Carrier Ethernet, Data Center, Edge, Enterprise, Industrial Networking and Security domains for over a decade. AMERICAS: +1-408-850-1247 | ASIA: +91 (44) 45 67 22 22 | EUROPE: +44-203-371-8691

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RATTINA PRABA ANNAMALAI MADHAN PANCHAKSHARAM … · MEF 6.1, the Ethernet Service Specification...

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