The 5 Attributes of Carrier Ethernet

What is Carrier Ethernet?

The Metro Ethernet Forum (MEF) is a standards body that defines services, develops standards and certification programs, and promotes the global adoption of Carrier Ethernet.

Carrier Ethernet is ubiquitous, standardized, carrier-class Ethernet Services and Networks characterized by five specific attributes. These 5 attributes distinguish Carrier Ethernet from familiar LAN based Ethernet:

1. Standardized Services
2. Reliability
3. Scalability
4. Service Management
5. Quality of Service

1. Standardized Services

Carrier Ethernet services are ubiquitous, standardized services delivered globally & locally. These standardized services include Ethernet Private Line (E-Line), Ethernet Private LAN (E-LAN services), Ethernet Virtual Private Line and Ethernet Virtual Private LAN services (several services multiplexed via one network interface). Carrier Ethernet services can be delivered to the customer without requiring the customer to change their network or LAN equipment.

The MEF Certification Program for Carrier Ethernet ensures the delivery of Carrier Ethernet with the five attributes. The MEF certifies both a service provider’s ability to deliver Carrier Ethernet services as well as an equipment vendor’s ability to carry Carrier Ethernet services. The MEF certification ensures ubiquitous and globally consistent service delivery.

iConverter Network Interface Devices are MEF 9 certified compliant. MEF 9 includes the delivery of Ethernet Private Line, Ethernet Virtual Private Line, Ethernet Private LAN and Ethernet Virtual Private LAN services. Ethernet Line services provide point-to-point Ethernet connectivity. Ethernet LAN services are used to interconnect multiple sites.

MEF 14
iConverter NIDs are MEF 14 certified compliant. MEF 14 includes Service Performance and Bandwidth Profiles. Service Performance is quantified by three parameters: Frame Delay (FD), Frame Delay Variation (FDV) and Frame Loss Ratio. Bandwidth Profiles include the following parameters: Committed Information Rate (CIR), Committed Burst Size (CBS), Excess Information Rate (EIR), and Excess Burst Size (EBS). Bandwidth Profiles are delivered through traffic management policing and shaping functions.

2. Reliability

Carrier Ethernet services must meet the most demanding quality and availability requirements. Networks must detect and recover from incidents without impacting users. This reliability is achieved with Service OAM for rapid fault detection and management, and protection (redundancy) with geographical diversity and rapid recovery. iConverter NIDs enable reliable Ethernet services with end-to-end Service OAM and redundant link protection.

• IEEE 802.1ag Connectivity Fault Management
• ITU-T Y.1731 Performance Monitoring
• IEEE 802.3ah Link OAM
• Link Fail with 50ms Failover Protection Switching
• ITU-T G.8031 Ethernet Linear Protection

3. Scalability

Carrier Ethernet services must be scalable in bandwidth delivery. iConverter NIDs deliver scalable bandwidth from < 1 Mbps to 1 Gbps in granular increments. The network must also be scalable, delivering services to subscribers globally. iConverter NIDs are compact, cost effective and can be easily deployed everywhere with zero-touch provisioning and built-in RFC 2544 test-head.

4. Service Management

Service management includes software and network management systems used to provision, troubleshoot and maintain the network. Service Providers must have the ability to monitor, diagnose and centrally manage their network, using standards-based vendor independent implementations. iConverter NIDs support TELNET, SNMPv3 and Secure IP-Less management that can be integrated into telecom management and OSS systems. iConverter management controls remote provisioning, and Service OAM performance monitoring and fault notification.

5. Quality of Service

Carrier Ethernet services provide Quality of Service with a wide variety of tiered service options. Service Level Agreements (SLAs) guarantee end-to-end performance for subscriber applications such as voice, video and data. iConverter NIDs support Quality of Service prioritization and ITU-T Performance Monitoring that enables delivery of services with SLAs with end-to-end performance guarantees.

The Carrier Ethernet Ecosystem

Single Service Provider Carrier Ethernet Network Diagram

The illustration above shows a typical point-to-point Ethernet Virtual Connection (EVC) between two Subscriber locations over one Service Provider network (in-franchise). This Carrier Ethernet network diagram contains the following elements:

EVC: The Ethernet Virtual Connection represents the Ethernet service or connection between two or more UNI interfaces. EVCs can be port based (i.e., all Subscriber traffic on a UNI port), or virtual (i.e., all Subscriber traffic carried over a Service Provider VLAN). EVCs can be point-to-point and connect two UNIs, or multipoint-to-multipoint and connect more than two UNIs.

CPE: The Customer Premise Equipment is Subscriber-owned network equipment at the edge of the Subscriber’s LAN or Enterprise network, and interfaces with a Carrier’s Metro Ethernet network.

UNI: User-to-Network Interface is the physical interface or port through which the Service Provider delivers the service to the Subscriber. The UNI is where the point of responsibility changes from the Service Provider to the Subscriber. The UNI can also be considered as the starting and ending point for the EVC. The UNI is the customer-facing port on the NID.

NID: The Network Interface Device is demarcation equipment that delivers Ethernet services via a UNI interface. The NID ensures service quality, monitors performance, facilitates troubleshooting, and converts between different physical media (for example, converting the Service Provider’s fiber interface to a copper UTP Subscriber interface). The NID is typically located at the Subscriber's site, and is owned and managed by the Service Provider or Operator.

Multiple Service Provider Carrier Ethernet Network Diagram

The illustration above shows a wholesale point-to-point EVC between two Subscriber locations over two Service Provider networks. The Service Provider partners with an Access Provider to reach a remote customer location (out-of-franchise). This Carrier Ethernet network diagram contains the following elements:

ENNI: The External Network to Network Interface provides the interconnection point between the two networks when more than one Service Provider is involved in delivering an Ethernet service. In the example above, it is the point where the Service Provider and the Wholesale Operator hand off the service(s) to each other.

E-Access Service: E-Access Service is wholesale service provided by the Access Provider and sold to the Service Provider who is delivering a Carrier Ethernet service to an out-of-franchise subscriber. The E-Access Service is the wholesales service between the ENNI and the UNI at the out-of-franchise subscriber location.

Types of Ethernet Services

The EVC (in the figure below) is a point-to-point E-Line service, and can be used for either Ethernet Private Lines or Ethernet Virtual Private Lines. Ethernet Private Lines use dedicated UNIs for point-to-point connections, and contain a single EVC per UNI. Ethernet Private Lines are the most popular Ethernet service due to their simplicity.

Ethernet Virtual Private Lines (EVPL) are often used to replace Frame Relay or ATM services, by supporting a service-multiplexed UNI (multiple EVCs per UNI), and supporting multiple EVPLs from a single physical connection (UNI) at the customer premise.

E-LAN Services are comprised of multi-point to multi-point EVCs. An E-LAN can be used to create a Transparent LAN Service, such as a multi-point L2 VPN.

E-Tree is a rooted point to multi-point service and is used for broadcast applications where services flow from a centralized point. E-Tree Services are used for video on demand, internet access, triple play backhaul, mobile cell site backhaul, and franchising applications. E-Tree provides traffic separation between the remote “Leaf” UNIs. Traffic from any “Leaf” UNI can be sent to and from “Root” UNI(s) but are not directly forwarded to other “Leaf” UNIs.

Ethernet Virtual Private Lines

iConverter NIDs support Ethernet Virtual Private Lines (EVPL), or service multiplexing, in which multiple services are aggregated on a single User-to-Network Interface (UNI). Each service is distinguished from the others by using 802.1q VLAN tag identification.

A single UNI, or port, can terminate multiple Ethernet Virtual Connections (EVC), with each EVC connecting to different remote locations. In addition, a UNI with Service Multiplexing capability can identify different traffic received from the Customer Premise Equipment, and map different traffic to different EVCs, destined for different remote locations.

Service Multiplexing lowers costs for carriers in a variety of ways:

• Lowers equipment costs by minimizing the number of customer router or switch ports required
• Minimizes space, power, and cabling
• Simplifies new service activation

All NID ports support Service Multiplexing when configured as a UNI, and using Y.1731 can independently monitor and track the performance matrix of each EVC, all the way down to individual Class of Service levels within the EVC.

Multiple Classes of Service

iConverter NIDs support the delivery of Multiple Classes of Service (CoS) for an Ethernet Virtual Connection. Each CoS can have unique service level performance attributes within the same EVC. A CoS with short delay and low jitter can be assigned to applications that require the best Quality of Service. ITU-T Y.1731 can independently monitor and track each CoS within an EVC, ensuring SLAs are met for each specific CoS.

End-to-End Service OAM

Providing reliable Ethernet services and supporting enforceable SLA assurances requires Operations Administration and Maintenance (OAM) functions to provide fault management and performance monitoring of the entire Ethernet connection.

ITU-T Y.1731 and IEEE 802.1ag standards enable End-to-End Service OAM functions to accomplish these service delivery objectives across one or more carrier networks. 802.1ag Connectivity Fault Management improves reliability with OAM tools for instant fault notification and rapid fault isolation. Y.1731 monitors the performance of Ethernet services on both an EVC and Class of Service basis for Service Level Agreement (SLA) assurance.

End-to-End Service OAM spans the entire Ethernet service between demarcation points at each customer location (UNI to UNI). The UNI is the User-to-Network Interface that defines an Ethernet service demarcation point (physical port) between customer and service provider. The UNI also defines Service Attributes, Traffic Classification, Bandwidth Profiles, Tagging, and other service parameters. The Network Interface Device provides the UNI, and the OAM Intelligence that is required at the Customer Premises for End-to-End Service OAM.

This out-of-franchise (off-net) application illustrates an E-Line service between two customer locations that geographically spans two or more Independent Operator networks. The Service Provider responsible for the billing and service contract has installed iConverter NIDs at each subscriber location, which function as the end points of the Service Provider Maintenance Domain. Through 802.1ag and Y.1731 Service OAM, the NIDs constantly monitor the end-to-end service performance of the network, and the Service Provider has visibility across the Operators’ networks for assurance that the contracted Service Level Agreement expectations are being met.

Connectivity Fault Management

iConverter NIDs support the IEEE 802.1ag Connectivity Fault Management (CFM) for scalable, continuous fault monitoring of Ethernet services for subscriber, service provider and network operator, each operating at a different network domain level (layer). Key CFM features include:

• Continuity Check – A periodical keep-alive message exchanged between end-points of an Ethernet service in a domain level that provides proactive fault monitoring and automatic notification
• Link Trace – An Administrator-initiated command for rapid fault isolation that traces intermediate points from one end-point to another end-point of an Ethernet service
• Loop Back – An Administrator-initiated command for an end-point to request response from an intermediate-point or another end-point of an Ethernet service

Performance Monitoring

iConverter NIDs support ITU-T Y.1731 for continuous performance monitoring to ensure compliance to SLAs established between the service provider and the subscriber. Key SLA parameters include:

• Frame Delay – The amount of time it takes a frame to travel from one end-point to another end-point of an Ethernet service
• Frame Delay Variation (Jitter) – The statistical difference in the collection of Frame Delay readings between the end-points
• Frame Loss – The number of frames lost between the end-points of an Ethernet service
• Availability - The percentage of the time the service is operational