Comment 14 for bug 1556549

This seems to be an OVS limitation. See http://openvswitch.org/pipermail/dev/2016-February/066030.html
More specifically, the patch described on OVS mailing list removed the OVSDB limitation of 330 connections:
@@ -130,7 +130,6 @@ ovsdb_jsonrpc_server_create(void)
 {
     struct ovsdb_jsonrpc_server *server = xzalloc(sizeof *server);
     ovsdb_server_init(&server->up);
- server->max_sessions = 330; /* Random limit. */
     shash_init(&server->remotes);
     return server;
 }