What is an Edge Architecture?
A two-tiered architecture that provides for secure connections over the Internet
I do not know who first came out with this term "Edge", but one will find this term more commonly used in Microsoft Exchange context.
The role of the Exchange Server 2007 Edge Transport Server is to be an SMTP Gateway for incoming and outgoing E-Mail messages
Below is how Sun Microsystems deploy their internal Edge Architecture.
FE-net: Front-End Network (Edge Network)
BE-net: Back-End Network
Basically, there is a firewall in front of FE-net and there is another firewall between FE-net and BE-net. Pretty straight-forward.
PS: I'hv been asked many times what are the recommended hardware.
As a general guideline, for a small setup with less than 5,000 users, T1000 for FE components and T2000 for BE components. (Of course, these 2 models are EOL. Find equivalent will do)
For larger deployment, I do see T2000 for FE components and V490 for BE components.
Sun internally uses the following configuration: