Usage Scenario
By default, when a Layer 3 network connects to a PW network through VBDIF interfaces, the following problems exist:
- MTU fragmentation is not supported when the PW encapsulation process is used in the downstream direction.
- Downstream multicast traffic statistics for a VBDIF interface are statistics on traffic replicated for VBDIF interface's member interfaces.
After the forward-mode loopback command is run to set the packet forwarding mode to loopback, downstream MTU fragmentation is supported on a VBDIF interface and multicast traffic statistics are for a copy of traffic forwarded from the VBDIF interfaces.
Precautions
After the forwarding mode is set to loopback on a VBDIF interface, the interface's forwarding performance deteriorates. Set the forwarding mode as required.
The configuration fails if the following situations are met:
- A BD is bound to a VSI.
- The igmp-snooping enable command is run in the BD view.
- The mpls vpls convergence separate enable command is run in the system view or VSI view.