Useful utility to control bandwidth.

tc is a useful utility to control bandwidth and to simulate long distance links Here is the man page https://linux.die.net/man/8/tc

Example

Thanks to Taco (my collegue) for the tip

tc qdisc add dev eth0 root netem delay 100ms

For a 100ms delay for every packet traversing eth0. You may use a Linux 'gateway' node to simulate two DC.