Connectivity to current lan while cutting over to new vlan configured network

[Bobby-P]

Current LAN – Flat network. All endpoint have static IP assignment from the 172.17.5.0/24 range. Clients connected to Meraki switches and ports are configured as trunk ports. No vlans configured for current lan

Lan overhaul – Lan to be segmented into 4 lans. Have Cisco 9300 switch as new distribution switch with vlan’s and associated SVI’s created. Gateway of last resort set and can reach internet. Have confirmed when Meraki ports are set as access port that vlans are working and can see other devices in new vlans.

Problem: What do we do enable bi-directional communication between current lan and new vlan enabled configuration. Active Directory and DNS servers on current lan but endpoints in vlans cannot connect.  

[PhilipDAth]

Typically you would use trunk links between your Meraki switches and your 9300.

When on the Meraki switch you configure the ports that users plug into as access ports, in whatever VLAN they should be using.

[Bobby-P]

The port on our Meraki switch  that connects to our Catalyst 9300 set as a trunk port.  So is the the port on the Catalyst 9300.  We're moving to changing the ports on the Meraki's to access ports with the vlan assignments based on the type of endpoint.  We have confirmed that the vlan information is flowing the the link between the Meraki and the Catalyst.  

This is a significant change over and we're trying to maintain connectivity to the current LAN while we work on changing over to the new configuration

[OCT_OMG]

Do any of your new VLAN subnets overlap the current 172.17.5.0/24 subnet? Also, can you successfully PING all of them from the current LAN?

[Bobby-P · Accepted solution]

We use a 3rd party firewall / router service. At 1st they didn't think they could help us but after further discussion they are able to handle the routing and we have communication between the old LAN configuration and our new Vlan based network