What's the difference between Proxy ARP, CARP and Other in Virtual IP settings?"

[jobayereng]

Hi all,

I have implemented a 1:1 NAT for one of my host by following the instruction http://forum.pfsense.org/index.php/topic,13507.0.html. 
Situation is, I have two internet connections from two ISPs.  I am using pfsense for multi WAN load balancing for local network.  I want to use 2 Public IP addresses from two ISP that will NAT to one of my internal private IP address. I have done it and its working.  But when I create a virtual IP for any of my WAN connection by using the type “other” then my 1:1 NAT does not work. But when I choose “proxy ARP” it works.  Again when I change the type “proxy-ARP to other” it works for some hours and suddenly the 1:1 NAT stop the NAT process.  The main point is if I don’t choose Proxy-ARP at first, the 1:1 does not work. 
What's the main difference between "Proxy-ARP" and "Other” for creating Virtual IPs?  In which situation which one should be used?

[GruensFroeschli]

@http://forum.pfsense.org/index.php/topic:

Virtual IP's:
A Service cannot bind to an Proxy-ARP VIP. (Services on pfSense) use for that CARP instead.

You can NOT ping Proxy ARP VIP's
Use CARP VIP's instead.
http://forum.pfsense.org/index.php/topic,4499.0.html

A description of what the differences between the 3 types of VIPs are:
http://forum.pfsense.org/index.php/topic,3987.msg24632.html#msg24632

[jimp]

For future reference, I added some information on this to the FAQ section of the Doc Wiki

http://doc.pfsense.org/index.php/What_are_Virtual_IP_Addresses%3F