topic Loopback addresses and ARP in General Topics

Loopback addresses and ARP

rzg62s_BPC — Mon, 29 Apr 2013 04:43:42 GMT

I'd like to terminate VPN's on lookback addresses from my public range.

If my public interface is 1.1.1.1/24 and I want to terminate VPN's on .2 and .3 I create two loopback interfaces (place them in the Internet Zone) with the IP addresses of 1.1.1.2 and 1.1.1.3.

Should their subnets be /24 or /32? (I've see examples here that show it configured as /24 and as /32 - in both cases identical to, or part of the L3 subnet)

Is there an ARP implication with each selection?

That is, If I use 1.1.1.2/32 do I need to route the address to the PA or will it proxy ARP for it on my public interface?

Re: Loopback addresses and ARP

rzg62s_BPC — Mon, 29 Apr 2013 08:17:44 GMT

OK, just reviewed training notes and found loopbacks must be 32 bit addresses masks.

So I just need to know if the is any automagic ARP if the address is contained within the subnet of a L3 interface.

Re: Loopback addresses and ARP

ckindel — Fri, 07 Jun 2013 19:27:33 GMT

The PA will certainly respond to arp requests for addresses assigned to loopback interfaces. Automagically.