The Cisco switch must implement Rapid Spanning Tree Protocol (STP) where VLANs span multiple switches with redundant links.
An XCCDF Rule
Description
<VulnDiscussion>STP is implemented on bridges and switches to prevent Layer 2 loops when a broadcast domain spans multiple bridges and switches and when redundant links are provisioned to provide high availability in case of link failures. Convergence time can be significantly reduced using Rapid STP (802.1w) instead of STP (802.1d), resulting in improved availability. Rapid STP should be deployed by implementing either Rapid Per-VLAN-Spanning-Tree (Rapid-PVST) or Multiple Spanning-Tree Protocol (MSTP). The latter scales much better when there are many VLANs.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-220638r539671_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
Configure Rapid STP or MSTP to be implemented at the access and distribution layers where VLANs span multiple switches as shown in the examples below:
SW2(config)#spanning-tree mode rapid-pvst
or