The 802.1t standard introduced the extended system ID to conserve MAC addresses while still allowing for a unique BID for each VLAN. In order to support extended VLANs, the Bridge Priority is reduced to a 4-bit value and a 12-bit Extended System ID field is added. STP then uses the extended system ID, the switch priority, and a single MAC address to make a unique BID for each VLAN. This is illustrated in Figure 3-14 below:
Fig. 3-14. 802.1t BID Composition
With extended system ID enabled, the Bridge . . .
The content below this message is for members only.