+----------+                             +-------------+
 | LISP     |                             | non-LISP    |
 | Domain A |                             | Domain B    |
 |  +-------+        +-----------+        |             |
 |  | ITR A |------->| Proxy-ETR |------->|             |
 |  +-------+        +-----------+        |             |
 |          |                             |             |
 +----------+                             +-------------+