CISC-L2-000230 - The Cisco switch must have the default VLAN pruned from all trunk ports that do not require it.

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This audit has been deprecated and will be removed in a future update.

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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 not performed this check. Please review the benchmark to ensure target compliance.


Prune VLAN 1 from any trunk links as necessary:

SW1(config)#int g0/2
SW1(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 vlan
Gi0/1 on 802.1q trunking 1
Gi0/2 on 802.1q trunking 1

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

See Also

Item Details

References: CAT|II, CCI|CCI-000366, Rule-ID|SV-220643r539671_rule, STIG-ID|CISC-L2-000230, STIG-Legacy|SV-110257, STIG-Legacy|V-101153, Vuln-ID|V-220643

Plugin: Cisco

Control ID: 5e146e85122ca42c7a8634d4ce527e0faf0b3b8f2b0f72d3519ce49ea3230d0a