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Emulab FAQ: Testbed Operations: How many VLANs should be created for an experiment?

Emulab FAQ: Testbed Operations: How many VLANs should be created for an experiment?

> Only *1* VLAN gets instantiated instead of 2:

Actually, this is not necessarily a problem. There are a couple reasons for this:

1) When using vnodes, it's possible that assign puts all members of a LAN on the same physical node, in which case no switch VLAN is needed.

2) When multiplexed links are being used, we have to do some tricks with the VLANs to make sure they can all talk to each other. Basically, we have to take the transitive closure of the set of interfaces that need to talk to each other. So, two or more NS file links/LANs may end up in the same switch VLAN.

3) When multiplexed links are being used, we may be using the same interface for two or more links, so you may see one switch VLAN that represents more than one LAN.