The system uses the Link Layer Discovery Protocol (LLDP) Fabric Connect Type-Length-Value (TLV) to communicate B-VLANs and system IDs between nodes in the SPB cloud. For more information about LLDP and its interaction with Fabric Attach, see Link Layer Discovery Protocol (802.1AB) Fundamentals.
| TLV Type | TLV Length | OUI | Subtype | Fabric Connect Capability | B-VLANs Number | B-VLAN-1 | B-VLAN-2 | System ID Length | System ID | 
|---|---|---|---|---|---|---|---|---|---|
| 7 bits | 9 bits | 3 octets | 1 byte | 1 byte | 1 byte | 2 bytes | 2 bytes | 1 byte | 6 bytes | 
| TLV Field | Description | 
|---|---|
| OUI | Specifies the Extreme OID value (0xd88466). | 
| Fabric Connect capability | Fabric Connect capability is enabled on all nodes that support Zero Touch Fabric Configuration. The value is 0 if the LLDP Fabric Connect TLV is not carrying any information in it. By default, the value is set to 1 on all ports. | 
| B-VLANs number | Specifies the number of B-VLANs that the TLV can carry. The LLDP Fabric Connect TLV supports an unlimited number of B-VLANs, but Zero Touch Fabric Configuration sends two B-VLANs through the TLV. The value is 0 if the node is sending default B-VLAN values. | 
| B-VLANs | Specifies the B-VLAN that is user-configured or dynamically learned from a neighbor node in the network. | 
| System ID Length | Specifies the length (in bytes) of the System ID. | 
| System ID | Specifies the IS-IS system ID. |