Spanning Tree Alternatives
If the preceding discussion has not convinced the reader that the use of the spanning
tree protocols is a viable option, here are a number of alternatives either available
today or in development in standards organizations. They include bridge gateways,
both within and among clouds; IEEE Project 802.1aq Shortest Path Bridging and IETF
TRILL, both described in ???ISP Access Services,??? later in the chapter; various proprietary
ring topology algorithms; and various proprietary paired virtual bridge solutions.
Bridge Gateways Either at a boundary between two bridged clouds, as between the provider
cloud and either of the customer clouds in Figure 13.13, or at the edge of a single
cloud, as in Figure 13.14, shown later in this section, a bridge or a cloud of bridges can be
separated from another bridge or cloud of bridges at arm??™s length, without the two bridges??™
or clouds??™ spanning trees being concatenated into a single spanning tree. This is important
because, as described in ???Interconnecting Clouds of Bridges??? carrying one cloud??™s BPDUs
over another cloud is undesirable. This technique can be called a bridge gateway.
Pages:
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911