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JUNOSe 11.1.x Link Layer Configuration Guide
Guidelines for Configuring 802.3ah OAM Link-Fault Management
Keep the following points in mind when you configure OAM link-fault management
on Ethernet interfaces:
Related Topics
Configuring 802.3ah OAM Link-Fault Management
Ethernet OAM link-fault management can be used for physical link-level fault detection
and management. It uses a new, optional sublayer in the data link layer of the OSI
model. Ethernet OAM can be implemented on any full-duplex point-to-point or
emulated point-to-point Ethernet link. A system-wide implementation is not required;
OAM can be deployed on particular interfaces of a router. Transmitted Ethernet OAM
242
Guidelines for Configuring 802.3ah OAM Link-Fault Management
The OAM application transmits and receives an OAM PDU at a maximum
frequency of every 100 milliseconds (10 OAM PDUs/sec) on every port on the
set of IOAs for a line module. The most impact on performance might occur on
ES2 4G LMs with two GE-8 I/O modules (16 ports) that cause 160 OAM PDUs to
be transmitted per second. Also, the OAM application must query MAC-layer
statistics (up to 6-8 for frame errors) every 10 seconds and errored symbol
statistics per second.
Because the outage time of the forwarding controller can last up to about 15
seconds or longer, the 802.3ah OAM feature does not support unified ISSU. The
link-fault management of Ethernet interfaces is halted during a unified ISSU
operation. Monitoring resumes immediately after the unified ISSU operation is
completed.
Although OAM configurations on an interface are preserved during a stateful
SRP switchover procedure, the retention of such OAM settings depends on the
time that the stateful SRP switchover process takes to complete. If the stateful
SRP switchover operation causes a traffic disruption of more than two seconds,
the previously configured OAM settings are affected. We recommend that you
configure the number of PDUs that are failed to be received by an OAM entity
before it generates a link fault/down event to be greater than two, and the high
and low thresholds for an error to be exceeded on an Ethernet OAM interface
to be more than two seconds.
802.3ah OAM functionality is not supported on SRP Ethernet interfaces. Also,
JUNOSe Software does not support unidirectional operation of Ethernet OAM
links, which enable the OAM entities to send Link Fault Information OAM PDUs
to the peer whenever a receive path failure is detected. In addition, an active
mode OAM entity can retrieve and respond to the performance variables that it
receives from its peer entity. However, the local OAM entity does not send a list
of such performance variables that it can process from the peer.
OAM Feature Overview on page 234
Interrelationship of OAM Link-Fault Management with Ethernet Subsystems on
page 240
Configuring 802.3ah OAM Link-Fault Management on page 242
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