802.3ah Clause 57 (EFM OAM) defines the Operations, Administration, and Maintenance (OAM) sublayer, which provides mechanisms useful for monitoring link operation such as remote fault indication and remote loopback control. In general, OAM provides network operators the ability to monitor the health of the network and quickly determine the location of failing links or fault conditions. EFM OAM described in this clause provides data link layer mechanisms that complement applications that may reside in higher layers.
OAM information is conveyed in slow protocol frames called OAM protocol data units (OAMPDUs). OAMPDUs contain the appropriate control and status information used to monitor, test, and troubleshoot OAM-enabled links. OAMPDUs traverse a single link being passed between peer OAM entities, and therefore, are not forwarded by MAC clients (like bridges or switches).
The following EFM OAM functions are supported:
EFM OAM capability discovery
active and passive modes
remote failure indication mechanism to handle critical link events, including link fault and dying gasp
dying gasp support; EFM OAM dying gasp messages and SNMP dying gasp messages are mutually exclusive and are generated on power failure. See the 7210 SAS-Mxp, R6, R12, S, Sx, T System Management Guide for more information about support for SNMP dying gasp.
All 7210 SAS platforms process the EFM OAM dying gasp message received on a port enabled for EFM and generate an SNMP trap. Support for generation of dying gasp messages on 7210 SAS platforms is listed in the following table.
7210 SAS platform |
Dying gasp message support 1 |
|---|---|
7210 SAS-Mxp |
✓ |
7210 SAS-R6 |
|
7210 SAS-R12 |
|
7210 SAS-Sx/S 1/10GE |
✓ |
7210 SAS-Sx 10/100GE |
✓ |
7210 SAS-T |
✓ |
loopback, a mechanism provided to support a data link layer frame-level loopback mode. Both remote and local loopback modes are supported.
EFM OAMPDU tunneling
high resolution timer for EFM OAM in 500ms interval (minimum)