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Root Guard

September 9th, 2017 in SWITCH 300-115 Go to comments

Question 1

Explanation

Root guard does not allow the port to become a STP root port, so the port is always STP-designated. If a better BPDU arrives on this port, root guard does not take the BPDU into account and elect a new STP root. Instead, root guard puts the port into the root-inconsistent STP state which is equal to a listening state. No traffic is forwarded across this port.

Below is an example of where to configure Root Guard on the ports. Notice that Root Guard is always configure on designated ports.

Root_Guard_Location.jpg

To configure Root Guard use this command:

Switch(config-if)# spanning-tree guard root

Reference: http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/10588-74.html

Question 2

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Question 6

Comments
  1. BL
    August 8th, 2017

    This question is come out today.

    Which feature do you implement so that an interface enter the root inconsistent state if it receives a superior BPDU?

    Answer: Root Guard

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