Removing the link between SW-D1 and SW-D2 if other critical devices are single attached to only one of the distribution switches could create potential pitfalls. Figure 11-6 shows the addition of a router R2 with a single attachment to SW-D2, and a server with a single attachment to SW-D2. As long as nothing goes wrong and all the interfaces stay up and running, reaching these new devices from anywhere in the network should not be a problem. Should a connection between an access layer switch and a distribution switch fail, as illustrated in Figure 11-6, communication is disrupted. Single-attached devices also represent a single point of failure in the design should the switch they are attached to fail completely.