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4.3.18.4 MEP
This switch supports two types of MEP: Port Down-MEPs and VLAN Down-MEPs.
Port Down-MEPs
In 802.1Q terminology, Port MEPs are located below the EISS entity, that is, closest to the physical port. Port
MEPs are used by e.g.
APS
Port MEPs are created when the encompassing service has type "Port".
Port MEPs may send OAM PDUs tagged or untagged. An OAM PDU will be sent untagged only if the MEP's
VLAN is set to "Inherit" (0). Any other value will cause it to be sent tagged with the port's TPID, whether or not the
VLAN matches the port's PVID and that PVID is meant to be sent untagged.
VLAN Down-MEPs
in 802.1Q terminology, VLAN MEPs are located above the EISS entity.
This means that tagging of OAM PDUs will follow the port's VLAN configuration.
Thus, if a VLAN MEP is created on the Port's PVID and PVID is configured to be untagged, OAM PDUs will be
transmitted untagged.
VLAN MEPs are created when the encompassing service has type "VLAN".
Down-MEP creation rules
There are a few rules to obey when creating Down-MEPs:
1. There can only be one Port MEP on the same port.
2. There can only be one VLAN MEP on the same port and VLAN.
3. A VLAN MEP must have a higher MD/MEG level than a Port MEP on the same port and VLAN.
These checks are performed automatically on administratively enabled MEPs when you change a particular MEP,
change the Service Type from Port to VLAN or vice versa, or change the domain's MD/MEG level.
for protection purposes.
Figure 4-3-103: CFM MEP Configuration
User's Manual of WGS-5225-8P2S Series
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