Root Guard
In a switched arrangement ambiance with aggregate authoritative ascendancy or in a account provider (SP) environment
where there are abounding access to added switches (into chump networks), it is important to analyze the
correct adjustment of the basis bridge. If possible, it is additionally important to analyze a specific agreed location
to accomplish an optimal forwarding loop-free topology. There is no apparatus in the accepted STP to accomplish the
position of the basis bridge, as any arch in a arrangement with a lower arch ID can accept the role of the root
bridge. Sometimes because of a misconfiguration, a spanning timberline may assemble afield by selecting an
imprecise about-face to be the basis switch. This bearings can be prevented by enabling the Basis Bouncer feature. For
example, you could accredit Basis Bouncer on SP-side about-face interfaces that affix to a customer-side switch.
With the Basis Bouncer affection implemented, if a about-face alfresco the SP arrangement becomes the basis switch, the
interface is put in a blocked state, and spanning timberline will baddest a new basis switch. The customer's about-face does
not become the basis about-face and is not in the aisle to the root.
With the Basis Bouncer feature, a Layer 2 interface is set as the appointed port, and if any accessory through this
port becomes the basis bridge, the interface is placed into the blocked (root-inconsistent) state. The Basis Guard
feature can be enabled by application the spanning-tree bouncer basis command in interface agreement mode.