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OAM Considerations
Ethernet CFM can be enabled on each individual path under an Ethernet tunnel. Only down MEPs
can be configured on each of them and CCM sessions can be enabled to monitor the liveliness of
the path using interval as low as 10 msec. Different CCM intervals can be supported on the
primary and secondary paths in an Ethernet tunnel.
MEPs can still be configured under the services independent of the Ethernet Tunnels.
The following rules control the interaction between the MEP defined under the eth-tunnel path and
the MEP defined in the service:
• The down MEPs configured on the eth-tunnel paths MUST be lower level than any down.
• MEPs configured on the associated SAP. The same applies for Virtual MEPs associated
with services such as BVPLS. Checks are provided to prevent the user from configuring
anything that violates the above rule. An error message is generated to indicate the
mismatch.
• Other service MEPs (up direction, down higher levels) are allowed with no restriction.
• Any down MEP on the associated SAP will transmit only over the active path entity.
QoS Considerations
When Ethernet tunnel is configured on two member ports located on different IOMs, the SAP
queues and virtual schedulers will be created with the actual parameters on each IOM.
The protection mode '8031-1to1' (default) activates only the primary path at any point in time,
guaranteeing the use of the desired QoS resources.
Ethernet tunnel CC messages transmitted over the SAP queues using the default egress QoS policy
will use NC (network class) as a forwarding class. If user traffic is assigned to the NC forwarding
class, it will compete for the same bandwidth resources with the Ethernet CCMs. As CCM loss
could lead to unnecessary bouncing of the Ethernet tunnel, congestion of the queues associated
with the NC traffic should be avoided. The operator must configure different QoS Policies to avoid
congestion for the CCM forwarding class by controlling the amount of traffic assigned into the
corresponding queue.
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