guide_c07-690079

On the top-left of Figure 1 (topology a), you see a design where two spines connect to a set of edge devices,
which looks more like an aggregation/access design. However, in contrast to designs based on Spanning Tree
Protocol, any two endpoints can take all available paths via either spine.
The second design, topology b at the top-right, illustrates a topology where servers connect to edge devices in
vPC mode, which in the case of FabricPath is called vPC+.
The left-bottom design, topology c, illustrates the ability for FabricPath to use multiple spines instead of just two.
This gives a very granular control on the available bandwidth: the more spines you add, the lower oversubscription
between the edge and the rest of the network.
The bottom-right design, topology d, illustrates the ability for FabricPath to provide direct connectivity between
edge devices in case direct communication between any edge devices is suitable. Most of these topologies would
not make sense with Spanning Tree, but they are almost plug-and-play topologies in a FabricPath environment.
Note: Direct connectivity between the spine devices is not strictly necessary. It depends on where the routing is
performed and on whether you consider it necessary to establish a direct communication path between spines,
whether spines are just used for fabric switching or are used for end node attachment too, and so on.
Figure 2 illustrates the traffic paths that any two given servers can take across a Cisco FabricPath topology:
Figure 2. Traffic paths in FabricPath designs
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