Working on creating docker container in CoreOS oeparting system, could any one let me know how to assign new IP range for setting up docker bridge

Open Source Projects Machine
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Operating system team asking to assign new IP range to docker demon such that in CoreOS operating system created below files

-rw-r–r--. 1 root root 34 Mar 15 10:04 05-br0.netdev
-rw-r–r--. 1 root root 44 Mar 15 10:03 10-eth0.network
-rw-r–r--. 1 root root 107 Mar 15 10:01 15-br0.network

mentioned required IP range , but unable to add bridge0 to

Machinename network # ip addr add xx.xx.xxx.xx/xx dev bridge0
Error: an inet prefix is expected rather than “xx.xx.xxx.xx/xx”.

noticed above error ,