together into virtual networks. This has several advantages:
- It's more secure because the QEMU instances use Unix domain
sockets to talk to the switch.
- It doesn't depend on the host's network interfaces. (Local
multicast fails if there is no default gateway, so for instance it
fails if a laptop is not connected to any network.)
- VDE devices can be connected together to form arbitrary network
topologies.
- VDE has a "wirefilter" tool to emulate delays and packet loss,
which are useful for network testing.
svn path=/nixos/trunk/; revision=25526
It turns out that all network interfaces in all VMs had the same
Ethernet address (52:54:00:12:34:56) because we didn't specify any
with the macaddr=... option. This can obviously lead to great
confusion. For instance, when a router forwards a packet, it can
actually end up sending the packet to itself because the target
machine has the same Ethernet address (causing a loop until the TTL
expires), while the target *also* receives the packet. It's amazing
anything worked at all, really.
So now we just set the Ethernet addresses to 52:54:00:12:<virtual
network number>:<machine number>.
svn path=/nixos/trunk/; revision=25020
