An engineer is working on a LAN switch and has noticed that its network connection to the mime Cisco IPS has gone down. Upon troubleshooting it is determined that the switch is working as expected…

Question

Options

• AThe upstream router has a misconfigured routing protocol
• BLink-state propagation is enabled
• CThe Cisco IPS has been configured to be in fail-open mode
• DThe Cisco IPS is configured in detection mode

• A
  3% (1)
• B
  83% (25)
• C
  10% (3)
• D
  3% (1)

Explanation

Link-State Propagation (LSP) is a feature on Cisco IPS inline pairs that ties together the link state of both interfaces in the pair. When one interface of the inline pair loses its link (e.g., the upstream router side goes down or the IPS detects a problem), LSP automatically brings down the paired interface as well-in this case, the interface connected to the LAN switch. This propagates the failure signal to the switch, causing it to detect the link as down even though the switch hardware itself is fully functional. This is exactly the described behavior: the switch is working correctly, but its port to the IPS went down because LSP was triggered. Fail-open mode (C) would allow traffic to bypass the IPS if it failed, not cause a link-down. Detection mode (D) is a passive IDS mode unrelated to link state.

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