Kbspecswitch
Emulab FAQ: Using the Testbed: Can I specify the switches to use in my links?
No, you cannot specify what switches your nodes are connected to. Nor can you request that a set of nodes be connected to the same switch.
Note that this is a highly unusual request and should not ever be necessary; if your experiment is dependent on this behaviour, you should contact us to explain why you think you need this.
For multicast related issues, please see the multicast FAQ entry.