[stack@packstack ~]$ sudo modprobe -r bridge
[sudo] password for stack:
[stack@packstack ~]$  ls /proc/sys/net/bridge/
ls: cannot access /proc/sys/net/bridge/: No such file or directory

[stack@packstack ~]$ sudo modprobe bridge
[stack@packstack ~]$  ls /proc/sys/net/bridge/
bridge-nf-call-arptables  bridge-nf-call-ip6tables  bridge-nf-call-iptables  bridge-nf-filter-pppoe-tagged  bridge-nf-filter-vlan-tagged  bridge-nf-pass-vlan-input-dev
[stack@packstack ~]$