Following up, you can add more than 2 computers to a network by adding them to the interfaces list specified in slice.add_l2network()
.
For example, if you wanted all 5 nodes to be on the same network (even across sites), you can just say
my_net = slice.add_l2network(name='net', interfaces=[iface1, iface2,iface3, iface4,iface5])
If you wanted to have two separate networks, one for site1 and one for site2, I would suggest doing
net1 = slice.add_l2network(name='net1', interfaces=[iface1, iface2])
net2 = slice.add_l2network(name='net2', interfaces=[iface3, iface4,iface5])
and then routing between them, I think by either by setting up routes between one node from each network, or by setting up an additional node to act as a router/switch and installing something like Open vSwitch (OVS).
I would appreciate it if someone could elaborate on how to set up routing between the nodes (not using OVS or something), as I am not familiar with doing this.