Link Monitoring; Remote Fault Detection - Alcatel-Lucent OmniSwitch 6850-48 Network Configuration Manual

Configuring EFM (LINK OAM)
The interconnected LINK OAM nodes notify the peer of their OAM configuration information and the
OAM capabilities of the local nodes by exchanging Information OAMPDUs and determine whether LINK
OAM connections can be established. A LINK OAM connection between two nodes is established only
when the settings concerning Loopback, link detecting, and link event of the both sides match.
Note. LINK OAM requires that frames be exchanged with a minimum frequency to maintain the relation-
ship( keep-alive). If no OAMPDUs are received in a 5 second window, the OAM peering relationship is
lost and must be restored to perform OAM functions. Use
configure the keepalive time interval.

Link Monitoring

Error detection in an Ethernet network is difficult, especially when the physical connection in the network
is not disconnected but network performance is degrading gradually. Link monitoring is used to detect and
indicate link faults in various environments. Link monitoring uses the Event Notification OAMPDU, and
sends events to the remote OAM node when there is a disorder detected on the link. The error events
defined are:
Errored frame event - An errored frame event occurs when the number of detected error frames over a
specific interval exceeds the predefined threshold.
Errored frame period event - An errored frame period event occurs if the number of frame errors in
specific number of received frames exceeds the predefined threshold.
Errored frame seconds event - When the number of error frame seconds detected on a port over a detec-
tion interval reaches the error threshold, an errored frame seconds event occurs.
For configuring errored frame, errored frame period, and errored frame seconds events on a port, see
"Configuring Link Monitoring" on page 16-10

Remote Fault detection

In a network where traffic is interrupted due to device failures or unavailability, the flag field defined in
OAMPDUs allows a LINK OAM enabled node to send severe error conditions to its peer. The severe
error conditions that can be identified are:
Dying Gasp - This flag is raised when a node is about to reset, reboot, or otherwise go to an operationally
down state. (An unexpected fault, such as power failure has occurred.)
Critical Event - This flag indicates a severe error condition that does not result in a complete reset or
reboot by the peer node. (An undetermined critical event happened.)
One of the most critical problems in an access network for carriers is differentiating between a simple
power failure at the customer premise and an equipment or facility failure. Dying gasp provides this infor-
mation by having a node indicate to the network that it is having a power failure. More details on the fail-
ure may be included in additional event information conveyed in the frame.
For setting up the notification of critical events on a port, see
Events" on page 16-9
OmniSwitch AOS Release 6 Network Configuration Guide
efm-oam port keepalive-interval
"Enabling and Disabling Propagation of
September 2009
LINK OAM Overview
command to
page 16-7