How MSTP BPDUs are transparently transmitted on a VPLS network

For S series switches (except the S1700), MSTP BPDUs are transparently transmitted on a VPLS network using the following methods:
1. Transmitting untagged BPDUs transparently
If BPDUs from a Layer 2 network do not carry tags, you need to run the port default vlan vlan-id and stp disable commands on the user-side interface of PE1. After receiving an untagged BPDU from the Layer 2 network, PE1 adds a specific tag to the BPDU and then transparently transmits the BPDU to PE2 over the VPLS network. After receiving the BPDU, PE2 removes the tag and then sends the BPDU to a specific attached user.
2. Transmitting tagged BPDUs transparently
If BPDUs from a Layer 2 network carry tags, you need to run the stp bpdu vlan vlan-id command on the user-side interfaces of devices on the Layer 2 network, and run the port trunk allow-pass vlan command on the user-side interface of PE1. After receiving a tagged BPDU from the Layer 2 network, PE1 transparently transmits the BPDU to PE2 over the VPLS network. After receiving the BPDU, PE2 directly sends the BPDU to a specific attached user.

Scroll to top