VLANs

All VLANs defined on your switches can be documented here.

VLAN list page

VLAN list page

The list page displays all of the L2 VLANs that have been defined along with all the switches that each VLAN is on. As with any list in the device42 portal, you can sort by multiple fields, you can search by vlan # or name, and clicking on the VLAN takes you to the details and edit page for that VLAN.

Adding a new VLAN

Adding a new VLAN

The VLAN # is the only required field in this form. The Name is automatically calculated as VLANxxxx if not entered. You can associate multiple switches with a VLAN.

Adding subnets as part of VLAN

Adding subnets as part of VLAN

While adding/editing a VLAN, you can define subnets that are part of this VLAN. Subnets are your L3 networks and can be part of a VLAN or not. You can define subnets for VLANs right on same page. Name, network and mask bits are required. Range begin and range end are optional and will be automatically calculated if not entered. Gateway is optional as well and will default to 0.0.0.0 if not entered.

Merging auto-discovered VLANs

Merging auto-discovered VLANs

With VLAN auto-discovery, all VLANs are pulled into Device42 from each switch that is discovered. During the discovery process, the system does not assume matching VLAN #’s from different switches are the same VLAN. It is common to have duplicate VLANs after running auto-discovery. While most duplicate VLANs are actually the same VLAN, it is not always true. The “Merge selected Vlans” bulk action is available to address this, i.e.: merge duplicate VLANs. There are two approaches for merging VLANs:

Select all the VLANs in Device42 and let the system merge all matching VLAN #’s to eliminate duplicates – example pictured above.
Select all VLANs on the list then choose “Merge selected Vlans” from the Action drop down menu then click Go.

Select specific subset of VLANs you wish to merge.
example: VLAN # 42 was discovered on 10 different switches and you know it is same VLAN and should be merged. Select the VLANs you want to merge then choose “Merge selected Vlans” from the Action drop down menu then click Go.

What happens when VLANs are merged?
Duplicate VLAN #’s are eliminated and all subnets, switch ports, mac addresses are consolidated into and associated with the merged VLAN.

Does VLAN merge prevent future duplicate VLANs?
Yes, but with one exception – VLANs on any newly discovered switches will be pulled in as unique VLAN – if/when this occurs, simply merge the newly discovered VLAN using the approach outline above.