Cisco Mx 100 warm spare setup how many public ip required

[Rahul]

We have two isp

We need HA setup mx 100 with warm spare 

Can you tell me how many public ip required for this setup.

Also we share diagram for the same. 

[JasonCampbell]

You need 3 public IPs - 1 for each firewall, and 1 for Virtual IP to share between the stack should one firewall go down. Technically you only need 2 public IPs, but the third minimizes failover and downtime. A /29 from each ISP would give you what you need.

[Rahul]

Yes we have /29 pool from both isp,

But I have doubt  how we can assign

There will be active and standby device.

So where we can assign these 2 public IPs

[jdsilva]

https://documentation.meraki.com/MX/Deployment_Guides/MX_Warm_Spare_-_High_Availability_Pair

[Rahul]

Still m confused, how we can use three public Ip, for heartbeat we can use private ip. 

There will be active and standby unit, so where we can assign public ip. 

On Standby unit or active unit?

For above diagram where we can assign those 2 public ip MXA or MXB ? 

[kYutobi]

If you have 2 ISP's I would think you only need 3 but you can ask how many IP's do your ISP provide. With the warm spare you can use the MX IP uplink and use virtual IPs.

[jdsilva]

You can do it with two (no NAT HA) or with three (With NAT HA), for each ISP.

The choice of which you use is up to you and your requirements.

[PhilipDAth · Accepted solution]

3 is the safe answer with the greatest HA options.  2 is also possible but recovering from a failure may take longer.

[Rahul]

yes thank you very much

means 

3 from each ISP connection, (2 VIPs and 4 IPs for MX 1 and MX 2 WAN links)