Migrating from Catalyst to Meraki - WAN link configuration

[KSanderson]

We currently use Cisco Catalyst switches and are migrating to Meraki MS425 as our core at each site.  We have 2 IPVPN links at the site that are currently configured as 2 P2P /30 links between the interface on the Catalyst and the providers router and we use OSPF.

Is it possible to migrate the 2 /30 links over to Meraki directly or do I need to involve the carrier to change the IP addresses of their routers into a /29 so that the 2 Meraki MS425 can have a management IP in the same VLAN and use the carrier router as the default gateway?  (we have done it that way at another site but this one is configured differently with the 2 /30 subnets and I'm trying not to have to get the WAN provider involved if at all possible).

Thanks.

[alemabrahao]

There is no need to involve the operator, and it is not a good practice to configure a public IP for the MS, it just needs to communicate with the Meraki cloud via the internet, so a private IP (as well as for the clients) does the trick.

Quick-Start

If you just want to get started without reading more in-depth information, follow these basic steps:

1. Unpack and mount your switch (desktop or rack mount) and power it on.
2. Plug any one of the Ethernet or fiber ports into an upstream device on your LAN. The uplink port should have access to a DHCP server and it will also need to be able to communicate with the internet.  
3. After powering on, your switch will download the latest software. While upgrading, the switch's power LED will flash green/white. Once the switch has checked into the dashboard, the LED will turn green/white. Note: A solid orange light indicates that the device has not checked in with the dashboard yet.
4. Log in to http://dashboard.meraki.com (For any devices that are used in mainland China, please visit http://dashboard.meraki.cn and create a new network. If you do not yet have a dashboard account, choose "Create an Account") Type in the serial number of your switch (found on the back of the unit) or simply enter your order number. This will create a new switch network.
5. Make your desired configuration changes under the Switch > Configure section of the dashboard.

For additional switch installation information, please refer to the MS Installation Guides article.

[KSanderson]

Sorry, maybe I haven't explained properly - the MS doesn't connect directly to the internet via a public IP - it backhauls to the Datacenter for Internet connectivity - this is for connectivity to the WAN.

What we have on the Cisco ports is

ip address 192.168.124.X 255.255.255.252
ip ospf network point-to-point
ip ospf 1 area 1
ip ospf cost 1

The other link has a higher cost.  In both cases, the other IP in the /30 is the carrier router.

My thinking was to create 2 VLAN interfaces with the IP addresses and assign them to OSPF with the carrier IP as the gateway.  The problem is what management IP can I add to the MS425 to allow connectivity?

[alemabrahao]

I'm not sure if what you're going to do will work. I don't think configuring two interfaces and enabling OSPF with different costs is the solution, the ideal would be to use IP SLA, but MS doesn't have this feature as far as I remember.

The ideal would be to use MX to balance the links or manipulate this preference.

[PhilipDAth]

I see you as having two options.

Do a cutover migration.  Configure the Meraki switches with the same config as the current switches, and then on the day of the cut over move the WAN circuits across from the old to the new switches.  No changes are needed by the carrier.

Do a staged migration where both old and new kit are hot at the same time.  Yes, you'll need to change both /30s to /29's as you have stated, so everything can be online at the same time.