Detections
Analytics

1.18 CISC-L2-000230

Information

The Cisco switch must have the default VLAN pruned from all trunk ports that do not require it.

GROUP ID: V-220643RULE ID: SV-220643r991850

The default VLAN (i.e., VLAN 1) is a special VLAN used for control plane traffic such as Spanning-Tree Protocol (STP), Dynamic Trunking Protocol (DTP), VLAN Trunking Protocol (VTP), and Port Aggregation Protocol (PAgP). VLAN 1 is enabled on all trunks and ports by default.

With larger campus networks, care must be taken about the diameter of the STP domain for the default VLAN. Instability in one part of the network could affect the default VLAN, influencing control-plane stability and therefore STP stability for all other VLANs.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

Prune VLAN 1 from any trunk links as necessary:

SW1(config)#int g0/2SW1(config-if)#switchport trunk allowed vlan except 1

Verify that VLAN 1 is not allowed on the trunk link:

SW1#show interfaces trunk

Port Mode Encapsulation Status Native vlanGi0/1 on 802.1q trunking 1Gi0/2 on 802.1q trunking 1

Port Vlans allowed on trunkGi0/1 1-998,1000-4094Gi0/2 2-4094

See Also

https://workbench.cisecurity.org/benchmarks/23798

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7, CCI|CCI-004891, Rule-ID|SV-220643r991850_rule, STIG-ID|CISC-L2-000230, Vuln-ID|V-220643

Plugin: Cisco

Control ID: 4a3bdbab16a47ce4cfb07ab33c48452a1384a6113d5f863e1da9d9a92efd8923