This is Luffy.
I tried to set warm spare using two MX device.
So I found below link.
According to link there are two option as below.
Option1 Use MX uplink IPs: When using this option, the current Active MX will use its distinct uplink IP or IPs when sending traffic out to the Internet. This option does not require additional public IPs for Internet-facing MXes, but also results in more disruptive failover because the source IP of outbound flows will change.
Option2 Use virtual uplink IPs: When using this option, both MXes will use a shared virtual IP (vIP) when sending traffic out to the Internet. This option requires an additional public IP per uplink but allows for seamless failover because the IP address the network is using to communicate with the Internet will be consistent. The vIP for each uplink must be in the same subnet as the IPs of the MXes themselves for that uplink, and the vIP must be different from both MX uplink IPs.
If both MX are connected to an ISP modem directly, I have some questions as below.
Q1. In case of Option 1, Does it need only a public IP ?
If so, do they have same public IP in both MX device ?
Q2. In case of Option 2, To set vIP, Does it need 3 public IP ?