Identifier that maps to different networks at different datacenters

A non-transitory machine readable medium storing a program for a network manager which when executed by at least one processing unit manages a plurality of managed forwarding elements at a particular datacenter, the program comprising:

• receiving a configuration for a bridge between a logical L2 network that spans at least two datacenters and physical L2 networks at one or more of the spanned datacenters, wherein the configuration includes a generic physical network identifier;
• mapping the generic physical network identifier to a particular physical L2 network at the particular datacenter, wherein the generic physical network identifier maps to other physical networks at other spanned datacenters;
• and
• providing the configuration to a set of central controllers using an identifier for the particular physical L2 network, wherein the set of central controllers configures a managed forwarding element operating at the particular datacenter to implement the bridge to bridge packets between the logical L2 network and the particular physical L2 network.