Согласно man'у:
	brctl setgcint <brname> <time> sets the garbage collection interval for the bridge <brname> to <time> seconds. This means that the bridge will check the forwarding database for timed out entries every <time> seconds.

Шаги воспроизведения:
	# brctl setgcint br0 10

Результат:
	never heard of command [setgcint]
	Usage: brctl [commands]
	commands:
	        addbr           <bridge>                add bridge
	        delbr           <bridge>                delete bridge
	        addif           <bridge> <device>       add interface to bridge
	        delif           <bridge> <device>       delete interface from bridge
	        hairpin         <bridge> <port> {on|off}        turn hairpin on/off
	        setageing       <bridge> <time>         set ageing time
	        setbridgeprio   <bridge> <prio>         set bridge priority
	        setfd           <bridge> <time>         set bridge forward delay
	        sethello        <bridge> <time>         set hello time
	        setmaxage       <bridge> <time>         set max message age
	        setpathcost     <bridge> <port> <cost>  set path cost
	        setportprio     <bridge> <port> <prio>  set port priority
	        show            [ <bridge> ]            show a list of bridges
	        showmacs        <bridge>                show a list of mac addrs
	        showstp         <bridge>                show bridge stp info
	        stp             <bridge> {on|off}       turn stp on/off

В /usr/sbin/ip-brctl такой в принципе нету:
	# cat /usr/sbin/ip-brctl | grep setgc
	# echo $?
	1