Demo Networking namespace

I tried to do practical of Networking deep-dive namespaces in AWS EC2 instance.
I created two namespace red & blue and tried to configure them so that they can ping each other. But after following all the steps, it gives me error "Network is unreachable"
Below is a snapshot attached for the error.
Please help me to point out if I missed any steps.
Thanks in advance

Hello, @paul0
Please set the netmask also. e.g.

$ ip -n red addr add 192.168.15.1/24 dev veth-red