Introduction of EFM OAM
- Tracy Yang
Overview
Ethernet in the First Mile (EFM) is the Ethernet physical layer specification which is mainly used between the link of the access layer and the aggregation layer for Ethernet management and maintenance. EFM is the link-level OAM (Operation and Management). For the link between two directly connected devices, it provides link connectivity detection function, link failure monitoring function and remote loopback function.
Figure 1. Networking diagram for Ethernet OAM
Types of EFM OAMPDU
EFM works at the data link layer, and its protocol messages are called OAMPDUs (OAM Protocol Data Units). EFM detects and reports link status through periodic OAMPDUs between devices, enabling network administrators to manage the network effectively. Table 1 shows the OAMPDUs types supported by PICOS.
Table 1. Types of EFM OAMPDU Supported by PICOS
OAMPDU Type | Description |
Information OAMPDU | For EFM peer discovery, the OAM entity in the handshake phase periodically sends Information OAMPDUs at certain period to detect the connectivity of a link. |
Loopback Control OAMPDU | It is used for remote loopback operation to control the OAM loopback state of the remote device, and to enable or disable the remote loopback function according to the remote loopback enabling or disabling information in the OAMPDU. |