참고 자료:
http://www.linuxfoundation.org/en/Net:Bridge
# brctl
# commands:
addbr <bridge> add bridge
delbr <bridge> delete bridge
addif <bridge> <device> add interface to bridge
delif <bridge> <device> delete interface from bridge
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 show a list of bridges
showmacs <bridge> show a list of mac addrs
showstp <bridge> show bridge stp info
stp <bridge> <state> turn stp on/off
(여기서 보면 bridge에 forwarding delay값을 설정할 수 있음)
virtualbox에서
http://www.virtualbox.org/wiki/Advanced_Networking_Linux