OAM F5 loopback

The OAM F5 loopback function of ATM operates in the following workflow on a PVC:

Each side of the PVC sends OAM cells to its peer periodically. On receiving an OAM cell from the sender, the receiver returns the OAM cell to the sender. If the sender receives the cell within the specified period (which is the interval frequency of sending OAM cells), the PVC is normal. If the sender fails to receive an OAM cell sent by itself, the PVC might be faulty. Then the sender continues to send OAM cells for detection (the sending interval is retry-frequency). If the sender still does not receive an OAM cell, the PVC is actually faulty.

Two methods are available for implementing the OAM F5 Loopback function: manual (OAMPing) and auto (OAM Frequency). In the OAMPing method, send OAM cells manually; this method is usually used for diagnosis. In the OAM Frequency method, you must configure an ATM interface to send OAM cells regularly at a certain interval; this method is usually used for automatic link status checking.