Specifications

Installation and Operation Manual Appendix C Operation, Administration, and Maintenance (OAM)
RICi-4E1/T1, RICi-8E1/T1 Ver. 2.0 OAM Flows C-7
• Unicast ETH-LB reception and reply transmission
Whenever a valid unicast ETH-LB request message is received by a MEP
(RICi-4E1/T1, RICi-8E1/T1), a unicast ETH-LB reply message is generated and
transmitted to the requesting MEP. Every field in the unicast ETH-LB request
message is copied to the unicast ETH-LB reply message with the following
exceptions:
 The source and destination MAC addresses are swapped
 The OpCode field is vendor-specific oxFE
 The Flow and MEP ID are processed as follows: if the Flow/MEP ID do not
exist in the device, it changes them to No Match” otherwise they are left
intact.
• Unicast ETH-LB reply receipt
When a unicast ETH-LB reply message is received by a MEP
(RICi-4E1/T1, RICi-8E1/T1) diagnostic flow termination function, it examines
the TLVs returned in the unicast ETH-LB reply message. The signal is declared
invalid if the TLVs do not match those sent in the corresponding unicast ETH-
LB request signal, including MEP ID and Flow ID.
• Continuity declarations
Loss of Continuity and Connectivity Mismatch states are declared by the
ETH-LB mechanism.
 Loss of continuity declaration
After the source device sends an ETH-LB message a timer is set with a
3.52 second timeout. If the destination device does send reply within the
timeout, the source enters the loss of continuity state. Upon reply from
the destination, the source resets the timer to 23.5 seconds. Regarding
the continuity check message, the source checks only the Flow ID with
the MEP ID. When the source enters the loss of continuity state, it adds
24 to Unavailable Seconds counter. The 23.5 second period is calculated
as a sliding window.
Loss of continuity state is cleared after 3.52 seconds with at least
21 reply messages from the destination. In this case the Unavailable
Seconds counter is decremented by 24.
 Connectivity mismatch declaration
If the source Flow ID is not equal to the destination Flow ID as recorded
in the reply message for 10 consecutive times, the source enters in to
misconnection state.
Misconnection state is cleared after 10 consecutive reply messages with
the correct flow name from the destination.
The Unavailable counter is maintained by the service according to the
number of PM messages that did not receive replies. If a mismatch
notification is received to the LB request, the frame is dropped and reply
message is not sent. This is why the service becomes unavailable (no
reply) in case of mismatch and the unavailable counter is raised.