Add a script to run interop tests against all versions of prod servers.
diff --git a/tools/run_tests/run_interop_tests.py b/tools/run_tests/run_interop_tests.py
index 1dc772a..86eb52b 100755
--- a/tools/run_tests/run_interop_tests.py
+++ b/tools/run_tests/run_interop_tests.py
@@ -589,7 +589,11 @@
     'cloud_gateway': ('216.239.32.255', 'grpc-test.sandbox.googleapis.com',
                       False),
     'cloud_gateway_v2': ('216.239.32.255', 'grpc-test2.sandbox.googleapis.com',
-                         True)
+                         True),
+    'gateway_v4': ('grpc-test4.sandbox.googleapis.com', 
+                   'grpc-test4.sandbox.googleapis.com', True), 
+    'cloud_gateway_v4': ('216.239.32.255', 'grpc-test4.sandbox.googleapis.com',
+                         True),
 }
 
 argp = argparse.ArgumentParser(description='Run interop tests.')