Metro Ethernet service had been brought the attention of service providers in the world wide since MEF (Metro Ethernet Forum) defined Carrier Ethernet as the standardized, ubiquitous network from five attributes to distinguish the Carrier Ethernet and LAN based Ethernet. These attributes are standardized services, scalability, reliability, Quality of Service as well as service management, respectively. Service providers can deploy the Ethernet services beyond metropolitan area then extend to the wide area. It brings the significant business benefits and make service providers migrate their network infrastructure to offer the Carrier Ethernet services for the enterprise, business,SOHO and residential end customers.
Millions of subscribers in the world wide have enjoyed the attractive conveniences of Ethernet services. Ethernet services are provided by standard, well-understood and widely available Ethernet interface. It requires no change of user’s existed LAN equipment and accommodates the existing network connectivity. The interconnection over Ethernet network devices makes the service providers simplify network operation, administration and maintenance (OAM). If offers the ability to centrally manage, diagnose and monitor the network performance by using standardized vendor naturally implementations.
Due to the widely usage on most of networking products, the reality of millions network device are used which is ideal for the widest variety applications for business, information sharing, communications as well as content services with data, voice and video. The service providers can extend the network from access and Metro based services to national and global based by implementing the popularly varied physical infrastructure equipment. Meanwhile, the Ethernet services can allow subscribers to adjust the bandwidth in granular increments, for example, in 1Mbps increment, for their applications demand. This makes subscribers just need to pay for only what they need bandwidth.
With managed Ethernet services, the service level agreements (SLA) between service providers and subscribers can deliver end-to-end network performance guarantee for data, voice and video over the converged Ethernet network. Additionally, it also offers the choice for quality of service options. This flexibility can make the subscriber not require to swap the new equipment and call for a visit of the service providers technician then enjoy the stable and reliable network service.
Ethernet Service OAM- Relevant Standards
IEEE 802.3ah –Ethernet First Mile
IEEE 802.3ah is a standard for Ethernet in the fist mile. It contains a link level OAM mechanism. In order to monitor link status, IEEE 802.3ah detects link failures in both bidirectional and unidirectional links by sending a CCM messages. If neither end receives a CCM within a specified duration, then a fault is detected against the service.
- Auto discovery : to eliminate the need of operator configuration
- Remote Loopback (Fault verification) : to provide on-demand link diagnostics, including bit-error-rate approximation
- Link Monitoring (Fault detection) : to offer proactive traffic based threshold link monitoring
- Critical Events (Fault notification) : Supports communication of network element conditions that may cause link failure
IEEE 802.1ag –Connectivity Fault Management
The 802.1ag allows an operator to detect, locate and verify faults for an Ethernet service. The connectivity check protocol is able to monitor the services continuously through periodically exchanging message to verify connectivity at a maintenance domain. If a failure is detected, the “Loopback” (for fault verification) and “Linktrace” (for fault isolation) protocols are triggered to discover vital connectivity data in a specific bridge or LAN.
- Continuity check (Fault detection) : Periodically exchange message to verify connectivity
- Lookback request (Fault verification) : To provide on-demand or proactive indication about the address of remote defected device
- Link monitoring (Fault isolation) : To provide the on-demand or proactive Ethernet network topology information
ITU-T Y.1731 –OAM Functions and Ethernet Based Networks
ITU-T Y.1731 specifies operate the maintain mechanisms for network and service of the Ethernet. In addition to the same set of connectivity fault protocols as IEEE 802.1ag, ITU-T Y.1731 also supports performance monitoring function. The major difference between these two standards is IEEE 802.1ag is tended to bridging applications, whereas ITU-Y Y.1731 has included bridging and transport applications in mind.
- Alarm Indication Signal (ETH-AIS) : To provide fault notification that a transport path or service instance failed in the Ethernet continuity check
- Remote Defect Indication (ETH-RDI) : To inform the connection failure of the other end of an Ethernet service
- Locked Signal (ETH-LCK) : Enables client to differentiate and isolate actual fault conditions
- Test Signal (ETH-Test) : Allow to send an one-way, on-demand, test signal to test throughput or detect frame loss
- Performance monitoring (ETH-PM) : To monitor traffic performance on a point-to-point, end-to-end VLAN-based Ethernet service
- Frame delay measurement (ETH-DM) : To provide an on-demand frame delay variation measurement between two points of the service
- Frame loss measurement (ETH-LM) : To collect frame loss information to evaluate severely error seconds which associate with service transport availabilitytest