Networking with Cisco

Just wanted to tell you that I added a new page, it’s aIP subnet calculator tool.

It works with IPv4 and IPv6 addresses, just remember to add the network length in the end (/24) for a 255.255.255.0

The danger with dynamic routing is the possibility of route overlaps, by this I mean having the same subnet defined on two routers announcing it in a dynamic routing protocol like for example OSPF.

Let us say you have configured a customer as 10.0.0.48/28 and he uses 10.0.0.49 and 10.0.0.50

Then you get a new customer and configure for example a new subnet 10.0.0.48/30, which is a more specific route (CIDR wise).

You might end up effectively blackholing the old customers traffic, this is something one should consider.

Use my IP subnet calculator tool to be sure not to overlap networks!