diff --git a/py25/bacpypes/__init__.py b/py25/bacpypes/__init__.py
index dbb45643..74c103c6 100755
--- a/py25/bacpypes/__init__.py
+++ b/py25/bacpypes/__init__.py
@@ -18,7 +18,7 @@
 #   Project Metadata
 #
 
-__version__ = '0.17.3'
+__version__ = '0.17.4'
 __author__ = 'Joel Bender'
 __email__ = 'joel@carrickbender.com'
 
diff --git a/py27/bacpypes/__init__.py b/py27/bacpypes/__init__.py
index dbb45643..74c103c6 100755
--- a/py27/bacpypes/__init__.py
+++ b/py27/bacpypes/__init__.py
@@ -18,7 +18,7 @@
 #   Project Metadata
 #
 
-__version__ = '0.17.3'
+__version__ = '0.17.4'
 __author__ = 'Joel Bender'
 __email__ = 'joel@carrickbender.com'
 
diff --git a/py34/bacpypes/__init__.py b/py34/bacpypes/__init__.py
index bddb1342..b8b48247 100755
--- a/py34/bacpypes/__init__.py
+++ b/py34/bacpypes/__init__.py
@@ -18,7 +18,7 @@
 #   Project Metadata
 #
 
-__version__ = '0.17.3'
+__version__ = '0.17.4'
 __author__ = 'Joel Bender'
 __email__ = 'joel@carrickbender.com'
 
diff --git a/sandbox/switch_demo.py b/sandbox/switch_demo.py
new file mode 100644
index 00000000..a4f621bf
--- /dev/null
+++ b/sandbox/switch_demo.py
@@ -0,0 +1,240 @@
+#!/usr/bin/python
+
+"""
+"""
+
+from bacpypes.debugging import bacpypes_debugging, ModuleLogger
+from bacpypes.consolelogging import ArgumentParser
+from bacpypes.consolecmd import ConsoleCmd
+
+from bacpypes.comm import Client, Server, Debug, bind
+from bacpypes.core import run, enable_sleeping
+
+# some debugging
+_debug = 0
+_log = ModuleLogger(globals())
+
+# globals
+this_console = None
+this_switch = None
+
+#
+#   DebugTerm
+#
+
+class DebugTerm(Debug):
+
+    """
+    A simple wrapper around the Debug class that prints out when it has been
+    activated and deactivated by the switch.
+    """
+
+    def activate(self):
+        print(self.label + " activated")
+
+    def deactivate(self):
+        print(self.label + " deactivated")
+
+#
+#    Switch
+#
+
+@bacpypes_debugging
+class Switch(Client, Server):
+
+    """
+    A Switch is a client and server that wraps around clients and/or servers
+    and provides a way to switch between them without unbinding and rebinding
+    the stack.
+    """
+
+    class TerminalWrapper(Client, Server):
+
+        def __init__(self, switch, terminal):
+            self.switch = switch
+            self.terminal = terminal
+
+            if isinstance(terminal, Server):
+                bind(self, terminal)
+            if isinstance(terminal, Client):
+                bind(terminal, self)
+
+        def indication(self, *args, **kwargs):
+            self.switch.request(*args, **kwargs)
+
+        def confirmation(self, *args, **kwargs):
+            self.switch.response(*args, **kwargs)
+
+    def __init__(self, **terminals):
+        if _debug: Switch._debug("__init__ %r", terminals)
+
+        Client.__init__(self)
+        Server.__init__(self)
+
+        # wrap the terminals
+        self.terminals = {k:Switch.TerminalWrapper(self, v) for k, v in terminals.items()}
+        self.current_terminal = None
+
+    def __getitem__(self, key):
+        if key not in self.terminals:
+            raise KeyError("%r not a terminal" % (key,))
+
+        # return the terminal, not the wrapper
+        return self.terminals[key].terminal
+
+    def __setitem__(self, key, term):
+        if key in self.terminals:
+            raise KeyError("%r already a terminal" % (key,))
+
+        # build a wrapper and map it
+        self.terminals[key] = Switch.TerminalWrapper(self, term)
+
+    def __delitem__(self, key):
+        if key not in self.terminals:
+            raise KeyError("%r not a terminal" % (key,))
+
+        # if deleting current terminal, deactivate it
+        term = self.terminals[key].terminal
+        if term is self.current_terminal:
+            terminal_deactivate = getattr(self.current_terminal, 'deactivate', None)
+            if terminal_deactivate:
+                terminal_deactivate()
+            self.current_terminal = None
+
+        del self.terminals[key]
+
+    def switch_terminal(self, key):
+        if key not in self.terminals:
+            raise KeyError("%r not a terminal" % (key,))
+
+        if self.current_terminal:
+            terminal_deactivate = getattr(self.current_terminal, 'deactivate', None)
+            if terminal_deactivate:
+                terminal_deactivate()
+
+        if key is None:
+            self.current_terminal = None
+        else:
+            self.current_terminal = self.terminals[key].terminal
+            terminal_activate = getattr(self.current_terminal, 'activate', None)
+            if terminal_activate:
+                terminal_activate()
+
+    def indication(self, *args, **kwargs):
+        """Downstream packet, send to current terminal."""
+        if not self.current_terminal:
+            raise RuntimeError("no active terminal")
+        if not isinstance(self.current_terminal, Server):
+            raise RuntimeError("current terminal not a server")
+
+        self.current_terminal.indication(*args, **kwargs)
+
+    def confirmation(self, *args, **kwargs):
+        """Upstream packet, send to current terminal."""
+        if not self.current_terminal:
+            raise RuntimeError("no active terminal")
+        if not isinstance(self.current_terminal, Client):
+            raise RuntimeError("current terminal not a client")
+
+        self.current_terminal.confirmation(*args, **kwargs)
+
+#
+#   TestConsoleCmd
+#
+
+@bacpypes_debugging
+class TestConsoleCmd(Client, Server, ConsoleCmd):
+
+    def __init__(self):
+        Client.__init__(self)
+        Server.__init__(self)
+        ConsoleCmd.__init__(self)
+
+    def do_request(self, args):
+        """request <msg>"""
+        args = args.split()
+        if _debug: TestConsoleCmd._debug("do_request %r", args)
+
+        # send the request down the stack
+        self.request(args[0])
+
+    def do_response(self, args):
+        """response <msg>"""
+        args = args.split()
+        if _debug: TestConsoleCmd._debug("do_response %r", args)
+
+        # send the response up the stack
+        self.response(args[0])
+
+    def do_switch(self, args):
+        """switch <arg>"""
+        args = args.split()
+        if _debug: TestConsoleCmd._debug("do_switch %r", args)
+        global this_switch
+
+        this_switch.switch_terminal(args[0])
+        print("switched")
+
+    def do_add(self, args):
+        args = args.split()
+        if _debug: TestConsoleCmd._debug("do_add %r", args)
+        global this_switch
+
+        # make a new terminal
+        this_switch[args[0]] = DebugTerm(args[0])
+
+    def do_del(self, args):
+        args = args.split()
+        if _debug: TestConsoleCmd._debug("do_del %r", args)
+        global this_switch
+
+        # delete the terminal
+        del this_switch[args[0]]
+
+    def indication(self, arg):
+        """Got a request, echo it back up the stack."""
+        print("indication: {}".format(arg))
+
+    def confirmation(self, arg):
+        print("confirmation: {}".format(arg))
+
+#
+#   main
+#
+
+@bacpypes_debugging
+def main():
+    # parse the command line arguments
+    args = ArgumentParser(description=__doc__).parse_args()
+    global this_switch, this_console
+
+    if _debug: _log.debug("initialization")
+    if _debug: _log.debug("    - args: %r", args)
+
+    # make some debugging terminals
+    debug1 = DebugTerm("a")
+    debug2 = DebugTerm("b")
+
+    # make a switch with them
+    this_switch = Switch(a=debug1, b=debug2)
+    if _debug: _log.debug("    this_switch: %r", this_switch)
+
+    # make a test console
+    this_console = TestConsoleCmd()
+    if _debug: _log.debug("    this_console: %r", this_console)
+
+    # bind the console to the top and bottom of the switch
+    bind(this_console, this_switch, this_console)
+
+    # enable sleeping will help with threads
+    enable_sleeping()
+
+    _log.debug("running")
+
+    run()
+
+    _log.debug("fini")
+
+if __name__ == "__main__":
+    main()
+