The layer 2 switch must have BPDU Guard enabled on all user-facing or untrusted access switch ports.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-206655	SRG-NET-000362-L2S-000022	SV-206655r383575_rule		Medium

Description
If a rogue switch is introduced into the topology and transmits a Bridge Protocol Data Unit (BPDU) with a lower bridge priority than the existing root bridge, it will become the new root bridge and cause a topology change, rendering the network in a suboptimal state. The STP PortFast BPDU guard enhancement allows network designers to enforce the STP domain borders and keep the active topology predictable. The devices behind the ports that have STP PortFast enabled are not able to influence the STP topology. At the reception of BPDUs, the BPDU guard operation disables the port that has PortFast configured. The BPDU guard transitions the port into errdisable state and sends a log message.

Description

If a rogue switch is introduced into the topology and transmits a Bridge Protocol Data Unit (BPDU) with a lower bridge priority than the existing root bridge, it will become the new root bridge and cause a topology change, rendering the network in a suboptimal state. The STP PortFast BPDU guard enhancement allows network designers to enforce the STP domain borders and keep the active topology predictable. The devices behind the ports that have STP PortFast enabled are not able to influence the STP topology. At the reception of BPDUs, the BPDU guard operation disables the port that has PortFast configured. The BPDU guard transitions the port into errdisable state and sends a log message.

STIG	Date
Layer 2 Switch Security Requirements Guide	2021-05-17

Details

Check Text ( C-6913r298395_chk )
Review the switch configuration to verify that BPDU Guard is enabled on all user-facing or untrusted access switch ports. If the switch has not enabled BPDU Guard, this is a finding.

Fix Text (F-6913r298396_fix)
Configure the switch to have BPDU Guard enabled on all user-facing or untrusted access switch ports.