netem provides Network Emulation functionality for testing protocols by emulating the properties of wide area networks. The current version emulates variable delay, loss, duplication and re-ordering. If you run a current 2.6 distribution, Bridge commands:

# ifconfig eth0 0.0.0.0 
# ifconfig eth1 0.0.0.0  
# brctl addbr mybridge 
# brctl addif mybridge eth0Bridge commands  
# ifconfig eth0 0.0.0.0 
# ifconfig eth1 0.0.0.0 
# brctl addbr mybridge 
# brctl addif mybridge eth0 
# brctl addif mybridge eth1 
# ifconfig mybridge up 
# tc qdisc add dev eth0 root netem delay 100ms 
# tc qdisc change dev eth0 root netem delay 100ms 10ms  
# brctl addif mybridge eth1 
# ifconfig mybridge up 
# tc qdisc add dev eth0 root netem delay 100ms 
# tc qdisc change dev eth0 root netem delay 100ms 10ms