Increase the scope of the network

[jeansouza]

Hello,

I currently use an open source firewall on my network, but I got a Meraki MX64 to test. I'm really enjoying it, but I came across the following situation:

In my network I use the ranges from IP 192.168.0.2 to 192.168.1.254, example below as it is set in the network scope of the current firewall:

In Meraki, in DHCP, I put the following configuration:

And in Addressing & VLANs I put like this:

Does anyone know if Meraki will distribute the IPs to the stations as it is in my current firewall, or do I need to do some more configuration?

[rhbirkelund]

What you are doing there, is basically the reverse. If you want to hand out addresses 0.2 - 0.254, and 1.1-1.254, You would have to reserve 192.168.0.1 and 192.168.0.255.

In reserved IP ranges, put;
192.168.0.1 , 192.168.0.1
and 192.168.0.255 , 192.168.0.255.

[jeansouza]

Like this?

[rhbirkelund]

Looks good 😊

[BrechtSchamp]

The first one will not be needed as the MX will not hand out its own address.

Secondly, what are you planning to do with the 255 address. It seems weird to reserve an address in the middle of your range.

[jeansouza]

But how will I know that MX will follow this network scope from 0.1-0.254 - 1.1-1.254 to the new devices that connect to the network?

[rhbirkelund]

You can verify the DHCP stats, by clicking on Security & SD-WAN -> Monitor -> Appliance Status, and then going to DHCP tab.

[jeansouza]

Here's how:

[BrechtSchamp]

Basically Meraki's DHCP server will hand out IP addresses from the range that was defined for the subnet in the Security & SD-WAN > Addressing & VLANs page.

In your case the subnet is 192.168.0.0/23. I assume you know what that /23 means, but if you don't... It means the following:

-network address for the subnet is 192.168.0.0 (cannot be used)

-broadcast address for the subnet is 192.168.1.255 (cannot be used)

-host addresses go from 192.168.0.1 up to 192.168.1.254 (can be used)

-subnet mask is 255.255.254.0

In you configuration the MX is configured to use 192.168.0.1 as its own address, so that will not be handed out to clients, the rest of the host addresses will be handed out to clients: 192.168.0.2 up to 192.168.1.254.

The Reserved IP ranges function is there for IP addresses you want to keep available for static IP configuration, or to be used by another DHCP server or... So those addresses will not be handed out to clients by Meraki MX DHCP (unless fixed assignment, see below).

The Fixed IP assignments list is for when you want to assign specific IP addresses to specific MAC-addresses via DHCP. You can use addresses from the reserved ranges here, and it's probably a good idea to do so. This list also gets edited when you assign fixed IP-addres to a client from the Network-Wide > Clients page.

The screenshot you posted shows some details about this range. We see that indeed there are 510 usable addresses in total (192.168.0.1 up to 192.168.1.254), 1 is used by the MX, and 2 are used by other clients. This leaves 507 free addreses.

Hope that's clear!