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

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-220669CISC-L2-000230SV-220669r991906_ruleCCI-004891medium
Description
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 needs to 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, thereby influencing control-plane stability and therefore STP stability for all other VLANs.
STIGDate
Cisco IOS XE Switch L2S Security Technical Implementation Guide2025-05-19

Related Frameworks

1 mapping across 3 frameworks
SCF0 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (3) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

CLD-03Cloud Infrastructure Security Subnet
0.50
NET-03.8Separate Subnet for Connecting to Different Security Domains
0.50
NET-06.1Security Management Subnets
0.50
NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (8) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

AC-17(2)Protection of Confidentiality and Integrity Using Encryption
1.00
AC-3Access Enforcement
1.00
CM-6Configuration Settings
1.00
SC-47Alternate Communications Paths
1.00
SC-7Boundary Protection
1.00
SC-7(11)Restrict Incoming Communications Traffic
1.00
SC-7(29)Separate Subnets to Isolate Functions
1.00
SC-8Transmission Confidentiality and Integrity
1.00
CCI1 mapping
CCI-004891
1.00

Details

Check Text (C-220669r991906_chk)

Review the switch configuration and verify that the default VLAN is pruned from trunk links that do not require it. 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 1-4094 If the default VLAN is not pruned from trunk links that should not be transporting frames for the VLAN, this is a finding.

Fix Text (F-22373r507556_fix)

Prune VLAN 1 from any trunk links as necessary. SW1(config)#int g0/2 SW1(config-if)#switchport trunk allowed vlan except 1 Verify 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