To make QEMU instances communicate with each other I needed to plug them to a "network". That's why I've created a bridge to which Virtual Instances would connect to. I've used the following script:
Then I just needed to start Qemu with this command line:
Since I've set up bridge for Qemu instances, I've plugged TAP interfaces into it. That's why I've needed to specify this in my qemu exec line. I've also added macaddress setting since both my instances were getting the same one.
And that's all! It works like a charm. Now on to some harder things!