Typically when requesting a block of IP addresses from an ISP, you get something like this:
Subnet - 11.12.13.0/28
Gateway 11.12.13.1
Useable Range - 11.12.13.2 - 11.12.13.14
This is where you are part of a subnet and you point your traffic to the default gateway in that subnet and the remaining addresses are yours to do what you want with in your network.
I recently have been involved with an ISP block delivered like this:
ISP Serial - 11.12.13.1/30
Customer Serial - 11.12.13.2/30
LAN Block - 20.21.22.0/29
This gives me a useable range of addresses of 20.21.22.1 - 20.21.22.7 correct?
Can I deal with this block and point to point link on one router?
Let's say all I have is a router (actually an ASA in my case but I'll deal with those specifics later). The ISP is connected to s3/0 using the assigned IP address from the ISP. Then from this point I would want to do the following:
1. Assign 1:1 NAT for servers as needed
2. Use 2 addresses for PAT with an internal private network.
I'm labbing this up and not seeing how this is done. I think I need to have an additional router in order to make this work, is that correct?
If my fa0/1 interface is using 192.168.0.1 255.255.255.0 and I want the network behind that to to PAT to say 20.21.22.2 how would I configure that? s3/0 has the /30 network, fa0/1 has the 192.168.0.0/24 network.. I don't imagine that I could assign the ip nat outside command to the s3/0 interface then NAT/PAT to one of the addresses in the assigned block for the fa0/1 interface, could I? It's not coming together and I think I need a L3 switch or some other router in front of my ASA in order to make this work. Could this be done with a VRF instance?
Thanks!
