Update: LISP solves the problem from client to server, IE Ingress Path Optimization. FHRP solves the problem from server to client, IE Egress Path Optimization. You can check out Egress Path Optimization here.
We recently published a Data Center Interconnect -- DCI- related document on cisco.com and I wanted to get it in front of you. Locator/Identifier Separator Protoc0l -- LISP -- provides the path optimization technology to forward transactions via the most direct path, ultimately meaning better application performance. The link for the LISP Virtual Machine Mobility paper is below.
As a side note, LISP can be used many other ways and here’s a pointer to one of our LISP pages.
For our purposes in DCI, we use LISP for path optimization and we can see here why the need arises. The box on the left shows an existing transaction that looks pretty direct. The middle box shows the workload is now in a new data center but the transaction is suboptimal, it still goes through the firsts data center. The box on the right shows the desired path, the direct path from user to workload withouth going through the first data center. It’s pretty easy to see the need here for path optimization and the desire to have the direct path to the new data center location as shown on the far right box.