pfSense – How to Set Up a High Availability Cluster

pfsenserouterswitchwan

I'm setting up a High Availability Cluster with two pfSense SG-4860 routers. I have a question about setting up the network. Here is the diagram they provide:

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I have a question about the WAN part. One of their prerequisites is:

  • A High Availability cluster needs three IP addresses in each subnet along with a separate unused subnet for the Sync interface. For WANs,
    this means that a /29 subnet or larger is required for an optimal
    configuration.

My question is: does this mean I need three external IP addresses from my ISP, or is it possible to do these internally with one external IP address from the ISP? Which would provide the best solution? I guess I'm just confused when it comes to this part of the network. Any feedback would be appreciated.

Edit:

I found this link on Super User: Can an ISP provide two static IPs over a single cable? Is this generally the way a network handles more than one IP address from an ISP?

Best Answer

The requirement is that each router have its own IP address (that's two), and there needs to be a virtual IP address (that makes three). If you are doing this on the public side, you will need three public addresses from your ISP, and that will require a maximum mask length of /29 since /30 will only give you two usable addresses.

I'm not sure what you mean by, "routing these to the switch," since switches don't know anything about IP addresses or routing.

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