IP Address Summarization

Requirements:

– 8+ subnets per site

– 3+ sites

– 500+ IPs per subnet

– 50+ Remote users (subnets within subnet) belonging to a site’s subnet

 

Note: our current LAN routes cannot easily be summarized. Therefore, I recommend that we keep our subnets within the subnet ranges of 10.5.0.0/19 to 10.5.126.0/19 so that it can be summarized as 10.5.0.0/17. The break-down is as follows:

 

Summary Route: 10.5.0.0/19 (Irvine)

10.5.0.0/23 (Servers: 10.5.0.0/24, SAN: 10.5.2.0/28)

10.5.2.0/23 (Users)

10.5.4.0/23 (Telecom)

10.5.6.0/23

10.5.8.0/23

10.5.10.0/23

10.5.12.0/23

10.5.14.0/23

10.5.16.0/23

10.5.18.0/23

10.5.20.0/23 (Trusted)

10.5.22.0/23 (Management)

10.5.24.0/23 (Guest)

10.5.26.0/23 (Isolation)

10.5.28.0/23 (DMZ)

10.5.30.0/23 => 10.5.30.0/29 to 10.5.31.255/29 (remote users: 64 subnets, each with 8 IPs)

 

Summary Route: 10.5.32.0/19 (Phoenix)

10.5.32.0/23 (Servers: 10.5.32.0/24, SAN: 10.5.33.0/28)

10.5.34.0/23 (Users)

10.5.36.0/23 (Telecom)

10.5.38.0/23

10.5.40.0/23

10.5.42.0/23

10.5.44.0/23

10.5.46.0/23

10.5.48.0/23

10.5.50.0/23

10.5.52.0/23

10.5.54.0/23 (Trusted)

10.5.56.0/23 (Management)

10.5.58.0/23 (Guest)

10.5.60.0/23 (Isolation)

10.5.62.0/23 (DMZ)

 

Summary Route: 10.5.64.0/19 (Florida)

10.5.64.0/23 (Servers: 10.5.64.0/24)

10.5.66.0/23 (Users)

10.5.68.0/23 (Telecom)

10.5.70.0/23

10.5.72.0/23

10.5.74.0/23

10.5.76.0/23

10.5.78.0/23

10.5.80.0/23

10.5.82.0/23

10.5.84.0/23

10.5.86.0/23 (Trusted)

10.5.88.0/23 (Management)

10.5.90.0/23 (Guest)

10.5.92.0/23 (Isolation)

10.5.94.0/23 (DMZ)

 

Summary Route: 10.5.96.0/19 (Reserved)

 

Summary Route: 10.5.128.0/24 (AWS)

10.5.128.0/26 (A)

10.5.128.64/26 (B)

10.5.128.128/26 (C)

10.5.128.192/26 (D)

 

SAN subnets should broadcast to as few IPs as possible. Thus, a mask of /28 with 16 possible IPs would highly optimize SAN traffic. This also enable us to have three entries on AWS route table as 10.5.128.0/24 (local), 10.5.0.0/17 (vgw-37fxxxx) and 0.0.0.0/0 (igw-7d0exxxx).

 

Sources:

How to summarize routes: https://learningnetwork.cisco.com/thread/23983

The easy way:

Calculate IP address range from CIDR: