Dell Force10 E600i FTOS Version 8.4.1.5 Configuration Guide for ExaScale - Page 907

Figure 49-10. VLAN Stacking without L2PT EE TREE SPANNING T INTERNE SPANNING TR REE NETWORK no spanning-tree T SERVICE PROVIDER w/ SPANNING TREE X Building B no spanning-tree Building A BPDU w/ destination MAC address: 01-80-C2-00-00-00 You might need to transport control traffic transparently through the intermediate network to the other region. Layer 2 Protocol Tunneling enables BPDUs to traverse the intermediate network by identifying frames with the Bridge Group Address, rewriting the destination MAC to a user-configured non-reserved address, and forwarding the frames. Since the frames now use a unique MAC address, BPDUs are treated as normal data frames by the switches in the intermediate network core. On egress edge of the intermediate network, the MAC address rewritten to the original MAC address and forwarded to the opposing network region (Figure 49-11). FTOS Behavior: In FTOS versions prior to 8.2.1.0, the MAC address that Dell Force10 systems use to overwrite the Bridge Group Address on ingress was non-configurable. The value of the L2PT MAC address was the Force10-unique MAC address, 01-01-e8-00-00-00. As such, with these FTOS versions, Dell Force10 systems are required at the egress edge of the intermediate network because only FTOS could recognize the significance of the destination MAC address and rewrite it to the original Bridge Group Address. In FTOS version 8.2.1.0 and later, the L2PT MAC address is user-configurable, so you can specify an address that non-Dell Force10 systems can recognize and rewrite the address at egress edge. Service Provider Bridging | 907