The multi-chassis ring can operate only if both nodes similarly configured. The peering relation must be configured and both nodes must be reachable at IP level. The multi-chassis ring with a corresponding sync-tag as a ring-name identifying a local port ID must be provision on both nodes. And the BFD session and corresponding interfaces must be configured consistently.
If the multi-chassis rings are not provisioned consistently, the ring does not become operational and the SAP managed by it is in an operationally up state on both nodes.
The assignment of individual SAPs to path-a and path-b is controlled by configuration of VLAN ranges according to the following rules:
By default, all SAPs (and therefore all VLANs on the specified port) are assigned to path-a.
An explicit statement defining the specified VLAN range assigns all SAPs falling into this range to the path-b.
An explicit statement defining the specified VLAN range defines all SAPs that are excluded from the multi-chassis ring control.
If a conflict in the configuration of VLAN ranges between two redundant nodes is detected, all SAPs falling into the ‟conflict-range” are assigned to path-a, on both nodes regardless the local configuration.
For QinQ-encapsulated ports the VLAN range refers to the outer VLAN.