Are you running in multi-host mode? I ask because in non-multi-host mode (ie where nova-network is only run on the "cloud controller"), compute nodes will not have IP addresses on their bridges.
You can restart networking, but then you must immediately restart nova-network so it can rebuild all of the bridges. I recommend trying this out in a sandbox environment first if possible. I do not recommend doing this on a node that does not have nova-network running on it.
• remove the IP from the bridge (ip addr del 1.2.3.4 dev br100) or
Then restart nova-network