IEEE 802.3ah EFM-OAM

The IEEE 802.3ah Ethernet in the First Mile (EFM) standard specifies the protocols and Ethernet interfaces for using Ethernet over access links as a first-mile technology.

Using the Ethernet in the First Mile solution, you will gain broadcast Internet access, in addition to services, such as Layer 2 transparent LAN services, voice services over Ethernet Access networks, and video and multicast applications, reinforced by security and Quality of Service control in order to build a scalable network.

The in-band management specified by IEEE 802.3ah EFM standard defines the operations, administration and maintenance (OAM) mechanism needed for the advanced monitoring and maintenance of Ethernet links in the first mile. The OAM capabilities facilitate network operation and troubleshooting. Basic 802.3 frames convey OAM data between two ends of the physical link. EFM-OAM is optional and can be disabled on each physical port.

When OAM is present, two connected OAM sub-layers exchange protocol data units (OAMPDUs). OAMPDUs are standard-size frames that can be sent at a maximum rate of 10 frames per second. This limitation is necessary for reducing the impact on the usable bandwidth. It is possible to send each frame several times in order to increase the probability of reception. A combination of the destination MAC address, the Ethernet type/length field and subtype allow distinguishing OAMPDU frames from other frames.

OAM functionality is designed to provide reliable service assurance mechanisms for both provider and customer networks.