Alcatel-Lucent 7750 SR OS, Interface Configuration Manual

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Interface Configuration
7750 SR OS Interface Configuration Guide Page 89
802.3ah OAM
802.3ah Clause 57 (EFM OAM) defines the Operations, Administration, and Maintenance (OAM)
sub-layer, 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 as such, 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 – handling of critical link events (link fault, dying gasp, etc.)
• Loopback — A mechanism is 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 100ms interval (minimum).
OAM Events
EFM OAM defines a set of events that may impact link operation. The following events are
supported:
• Critical link events (defined in 802.3ah clause 57.2.10.1)
→
Link fault: the PHY has determined a fault has occurred in the receive direction of the
local DTE.
→
Dying gasp: an unrecoverable local failure condition has occurred.
→
Critical event: an unspecified critical event has occurred.
These critical link events are signaled to the remote DTE by the flag field in OAM PDUs.