Can I subnet a subnet?
- by Portman
Apologies in advance for the botched terminology. I have read the Server Fault Subnet Wiki but this is more of an ISP question.
I currently have a /27 block of public IPs. I use give my router the first address in this pool and then use 1-to-1 NAT for all the servers behind the firewall, so that they each get their own public IP.
The router/firewall is currently using (actual addresses removed to protect the guilty):
IP Address: XXX.XXX.XXX.164
Subnet mask: 255.255.255.224
Gateway: XXX.XXX.XXX.161
What I would like to do is break out my subnet into two separate /28 subnets. And do this in a way that is transparent to the ISP (i.e., they see me as continuing to operate a single /27).
Currently, my topology looks like:
ISP
|
[Router/Firewall]
|
[Managed Ethernet Switch]
/ \ \
[Server1] [Server2] [Server3] (etc)
Instead, I would like it to look like:
ISP
|
[Switch]
/ \
[Router1] [Router2]
| | | |
[S1] [S2] [S3] [S4] (etc)
As you can see, this would partition me into two separate networks.
I'm struggling with what the correct IP settings would be on Router1 and Router2.
Here's what I have right now:
Router1 Router2
IP Address: XXX.XXX.XXX.164 XXX.XXX.XXX.180
Subnet mask: 255.255.255.240 255.255.255.240
Gateway: XXX.XXX.XXX.161 XXX.XXX.XXX.161
Note that normally you would expect Router2 to have a gateway of .177, but I'm trying to get them both to use the gateway originally given to me by the ISP.
Is subnetting like this in fact possible, or am I completely botching the most basic concepts?
