Accidentally Removed Allowed VLANs from Cisco Switch Dot1Q Trunk

Accidentally removed allowed VLANs from Cisco switch dot1q trunk

It is possible to accidentally remove allowed VLANs from a Cisco switch dot1q trunk. This mistake can cause serious network problems and downtime. In this article, we will discuss why this mistake should be avoided and how it can be remedied.

When a Cisco switch dot1q trunk is configured, the switch will only pass traffic from the configured VLANs. If a VLAN is not allowed, traffic from that VLAN will not be able to traverse the trunk. This mistake can easily be made, especially if there are multiple VLANs allowed on the trunk.

The mistake of accidentally removing allowed VLANs from a Cisco switch dot1q trunk can be avoided by ensuring that the VLANs are properly configured. This can be done by verifying the list of configured VLANs in the trunk during configuration. It is also important to ensure that the configuration is properly documented so that any changes can be tracked.

If the mistake of accidentally removing allowed VLANs from a Cisco switch dot1q trunk is made, the issue can be corrected by reconfiguring the VLANs on the trunk. This can be done by first determining which VLANs are allowed on the trunk and then adding them back in. It is important to note that traffic from VLANs that are not allowed on the trunk will be blocked, so it is important to ensure that the VLANs are properly configured.

It is also important to remember that VLANs can be configured on both ends of the trunk. This means that if the VLANs are removed from one end of the trunk, they must also be removed from the other end. It is also important to note that if the VLANs are not configured correctly, traffic can still traverse the trunk, but it will be blocked at the other end.

In conclusion, it is possible to accidentally remove allowed VLANs from a Cisco switch dot1q trunk. This mistake should be avoided by ensuring that the VLANs are properly configured and documented. If the mistake is made, it can be corrected by reconfiguring the VLANs on the trunk. It is also important to remember that VLANs must be configured on both ends of the trunk and that traffic from VLANs that are not allowed on the trunk will be blocked.