Trying to get the most usable IPs out of my /28 subnet from Charter

[Paul Gaydos]

We have a new /28 subnet from our ISP Charter Spectrum...

Internet Connection Information from Charter:

Network Block: xxx.xxx.xxx.64/28

Gateway: xxx.xxx.xxx.65

Subnet Mask: 255.255.255.240

First Useable IP: xxx.xxx.xxx.66

Last Useable IP: xxx.xxx.xxx.78

Trying to get at least 7 IPs out of this /28 subnet from Charter to use for my NAT rules on the ASA at this location for a couple of servers I have onsite there.

Right now as configured, I only have 4 IPs to use: xxx.xxx.xxx.74 - xxx.xxx.xxx.77. I have the Charter circuit connected to my ASR 1001-X on interface Gi0/0/1 (xxx.xxx.xxx.66/30). I then have Ethernet 0/2 (xxx.xxx.xxx.78/29) on the ASA connected to interface Gi0/0/3 (xxx.xxx.xxx.73/29) on the ASR.

Looking for any suggestions on how to get at least 7 IPs to use for NAT on the ASA.

Thanks!

Paul

[cofee · Accepted solution]

Paul,

With the subnet provided you only have 14 valid addresses to play with, so those 7 addresses have to come out of these14 available addresses. If you have already used majority of the address space and don't have 7 IPs available then either you would need get a new block of IPs or find a way to free up IPs, see if there is a way to use PAT for some hosts that are currently using static NATs or if there are devices in your network that are assigned addresses from this space that can use IPs from another address space, possibly from a private range.

Sorry can't think of anything else.

[Paul Gaydos]

Yeah, that is what I kind of figured.  I went ahead and moved the Charter circuit directly to the ASA.  With this setup, I now can fully use that /28 subnet on the ASA.  I then routed the Charter connection from the ASA to the ASR.