CANOGA PERKINS 9145EMP NID Software Version 4.0 - Manual (Page 145)

9145EMP NID Software User’s Manual Service OAM
Service OAM
130
There are no Up MEPs on the Network side, as there no domain starting towards the
User ports. MIPs can be located only on C-VLANs, on the User port. The S-VLAN domain
starts in the 9145EMP device, so there is no need for an intermediate monitoring port.
Figure 11-1 Positioning of SOAM entities
11.1.3 SOAM Protocols
SOAM Connectivity Fault Management provides the following protocols:
• Continuity Check Protocol: The continuity check message (CCM) is used to detect con-
nectivity failures in an MA/MEG. Each MEP can be configured to periodically transmit a
CCM. CCMs are sent to all MEPs associated with a given MA/MEG. Use of a multicast
destination address allows the discovery of remote MEP MAC addresses and the detec-
tion of leaks between MAs/MEGs. Every active MEP maintains a CCM database. As a
MEP receives CCMs, it updates the record in the database. If no CCM frames from a
peer MEP are received within the defined interval (3.5 times the CCM transmission
period), loss of continuity defect is detected.
• Loopback Protocols: A loopback message (LBM) is used to identify the specific fault
location. The MEP generates a loopback message addressed to a specific maintenance
point within an MA/MEG. The destination MIP or MEP must respond with a loopback reply
(LBR).
A single, multicast LBM can be generated by a Y.1731 MEP, and every far-end MEP in
the MA/MEG responds with a loopback reply; hence, the originating MEP will know all the
far end MEPs that have connectivity.
A sweep loopback procedure is used to detect the maximum transmission unit (MTU) size
for a given end-to-end connection. Loopback messages are sent continuously,
incrementing the MTU size for each new request (by increasing the size of the data type-
length-value (TLV) component). The network will drop frames above a certain
unsupported MTU, hence the originating MEP will not receive the expected responses.