diff --git a/network-transport.cabal b/network-transport.cabal
--- a/network-transport.cabal
+++ b/network-transport.cabal
@@ -1,5 +1,5 @@
 Name:          network-transport
-Version:       0.2.0.2
+Version:       0.3.0
 Cabal-Version: >=1.6
 Build-Type:    Simple
 License:       BSD3 
diff --git a/src/Network/Transport.hs b/src/Network/Transport.hs
--- a/src/Network/Transport.hs
+++ b/src/Network/Transport.hs
@@ -1,32 +1,36 @@
 -- | Network Transport 
-module Network.Transport ( -- * Types
-                           Transport(..)
-                         , EndPoint(..)
-                         , Connection(..)
-                         , Event(..)
-                         , ConnectionId
-                         , Reliability(..)
-                         , MulticastGroup(..)
-                         , EndPointAddress(..)
-                         , MulticastAddress(..)
-                           -- * Hints
-                         , ConnectHints(..)
-                         , defaultConnectHints
-                           -- * Error codes
-                         , TransportError(..)
-                         , NewEndPointErrorCode(..)
-                         , ConnectErrorCode(..)
-                         , NewMulticastGroupErrorCode(..)
-                         , ResolveMulticastGroupErrorCode(..)
-                         , SendErrorCode(..)
-                         , EventErrorCode(..)
-                         ) where
+module Network.Transport 
+  ( -- * Types
+    Transport(..)
+  , EndPoint(..)
+  , Connection(..)
+  , Event(..)
+  , ConnectionId
+  , Reliability(..)
+  , MulticastGroup(..)
+  , EndPointAddress(..)
+  , MulticastAddress(..)
+    -- * Hints
+  , ConnectHints(..)
+  , defaultConnectHints
+    -- * Error codes
+  , TransportError(..)
+  , NewEndPointErrorCode(..)
+  , ConnectErrorCode(..)
+  , NewMulticastGroupErrorCode(..)
+  , ResolveMulticastGroupErrorCode(..)
+  , SendErrorCode(..)
+  , EventErrorCode(..)
+  ) where
 
 import Data.ByteString (ByteString)
+import qualified Data.ByteString as BS (copy)
 import qualified Data.ByteString.Char8 as BSC (unpack)
 import Control.Exception (Exception)
+import Control.Applicative ((<$>))
 import Data.Typeable (Typeable)
-import Data.Binary (Binary)
+import Data.Binary (Binary(get, put))
+import Data.Word (Word64)
 
 --------------------------------------------------------------------------------
 -- Main API                                                                   --
@@ -48,6 +52,11 @@
     -- | EndPointAddress of the endpoint.
   , address :: EndPointAddress 
     -- | Create a new lightweight connection. 
+    --
+    -- 'connect' should be as asynchronous as possible; for instance, in
+    -- Transport implementations based on some heavy-weight underlying network
+    -- protocol (TCP, ssh), a call to 'connect' should be asynchronous when a
+    -- heavyweight connection has already been established.
   , connect :: EndPointAddress -> Reliability -> ConnectHints -> IO (Either (TransportError ConnectErrorCode) Connection)
     -- | Create a new multicast group.
   , newMulticastGroup :: IO (Either (TransportError NewMulticastGroupErrorCode) MulticastGroup)
@@ -60,6 +69,11 @@
 -- | Lightweight connection to an endpoint.
 data Connection = Connection {
     -- | Send a message on this connection.
+    -- 
+    -- 'send' provides vectored I/O, and allows multiple data segments to be
+    -- sent using a single call (cf. 'Network.Socket.ByteString.sendMany').
+    -- Note that this segment structure is entirely unrelated to the segment
+    -- structure /returned/ by a 'Received' event.
     send :: [ByteString] -> IO (Either (TransportError SendErrorCode) ())
     -- | Close the connection.
   , close :: IO ()
@@ -68,11 +82,13 @@
 -- | Event on an endpoint.
 data Event = 
     -- | Received a message
-    Received ConnectionId [ByteString]
+    Received {-# UNPACK #-} !ConnectionId [ByteString]
     -- | Connection closed
-  | ConnectionClosed ConnectionId
+  | ConnectionClosed {-# UNPACK #-} !ConnectionId
     -- | Connection opened
-  | ConnectionOpened ConnectionId Reliability EndPointAddress 
+    --
+    -- 'ConnectionId's need not be allocated contiguously.
+  | ConnectionOpened {-# UNPACK #-} !ConnectionId Reliability EndPointAddress 
     -- | Received multicast
   | ReceivedMulticast MulticastAddress [ByteString]
     -- | The endpoint got closed (manually, by a call to closeEndPoint or closeTransport)
@@ -82,7 +98,7 @@
   deriving (Show, Eq)
 
 -- | Connection data ConnectHintsIDs enable receivers to distinguish one connection from another.
-type ConnectionId = Int
+type ConnectionId = Word64 
 
 -- | Reliability guarantees of a connection.
 data Reliability = 
@@ -111,8 +127,12 @@
 
 -- | EndPointAddress of an endpoint.
 newtype EndPointAddress = EndPointAddress { endPointAddressToByteString :: ByteString }
-  deriving (Eq, Ord, Typeable, Binary)
+  deriving (Eq, Ord, Typeable)
 
+instance Binary EndPointAddress where
+  put = put . endPointAddressToByteString
+  get = EndPointAddress . BS.copy <$> get
+
 instance Show EndPointAddress where
   show = BSC.unpack . endPointAddressToByteString
 
@@ -219,8 +239,35 @@
     EventEndPointFailed
     -- | Transport-wide fatal error
   | EventTransportFailed
-    -- | Some incoming connections were closed abruptly.
-    -- If an endpoint address is specified, then all connections to and
-    -- from that endpoint are now lost
-  | EventConnectionLost (Maybe EndPointAddress) [ConnectionId] 
+    -- | We lost connection to another endpoint
+    --
+    -- Although "Network.Transport" provides multiple independent lightweight
+    -- connections between endpoints, those connections cannot /fail/
+    -- independently: once one connection has failed, /all/ connections, in
+    -- both directions, must now be considered to have failed; they fail as a
+    -- "bundle" of connections, with only a single "bundle" of connections per
+    -- endpoint at any point in time.
+    -- 
+    -- That is, suppose there are multiple connections in either direction
+    -- between endpoints A and B, and A receives a notification that it has
+    -- lost contact with B. Then A must not be able to send any further
+    -- messages to B on existing connections. 
+    --
+    -- Although B may not realize /immediately/ that its connection to A has
+    -- been broken, messages sent by B on existing connections should not be
+    -- delivered, and B must eventually get an EventConnectionLost message,
+    -- too. 
+    --
+    -- Moreover, this event must be posted before A has successfully
+    -- reconnected (in other words, if B notices a reconnection attempt from A,
+    -- it must post the EventConnectionLost before acknowledging the connection
+    -- from A) so that B will not receive events about new connections or
+    -- incoming messages from A without realizing that it got disconnected. 
+    -- 
+    -- If B attempts to establish another connection to A before it realized
+    -- that it got disconnected from A then it's okay for this connection
+    -- attempt to fail, and the EventConnectionLost to be posted at that point,
+    -- or for the EventConnectionLost to be posted and for the new connection
+    -- to be considered the first connection of the "new bundle".
+  | EventConnectionLost EndPointAddress 
   deriving (Show, Typeable, Eq)
diff --git a/src/Network/Transport/Internal.hs b/src/Network/Transport/Internal.hs
--- a/src/Network/Transport/Internal.hs
+++ b/src/Network/Transport/Internal.hs
@@ -1,22 +1,23 @@
 -- | Internal functions
-module Network.Transport.Internal ( -- * Encoders/decoders
-                                    encodeInt32
-                                  , decodeInt32
-                                  , encodeInt16
-                                  , decodeInt16
-                                  , prependLength
-                                    -- * Miscellaneous abstractions
-                                  , mapIOException
-                                  , tryIO
-                                  , tryToEnum
-                                  , timeoutMaybe
-                                  , asyncWhenCancelled
-                                  -- * Replicated functionality from "base"
-                                  , void
-                                  , forkIOWithUnmask
-                                    -- * Debugging
-                                  , tlog
-                                  ) where
+module Network.Transport.Internal 
+  ( -- * Encoders/decoders
+    encodeInt32
+  , decodeInt32
+  , encodeInt16
+  , decodeInt16
+  , prependLength
+    -- * Miscellaneous abstractions
+  , mapIOException
+  , tryIO
+  , tryToEnum
+  , timeoutMaybe
+  , asyncWhenCancelled
+  -- * Replicated functionality from "base"
+  , void
+  , forkIOWithUnmask
+    -- * Debugging
+  , tlog
+  ) where
 
 #if ! MIN_VERSION_base(4,6,0)
 import Prelude hiding (catch)
@@ -27,20 +28,23 @@
 import Foreign.ForeignPtr (withForeignPtr)
 import Data.ByteString (ByteString)
 import qualified Data.ByteString as BS (length)
-import qualified Data.ByteString.Internal as BSI ( unsafeCreate
-                                                 , toForeignPtr
-                                                 , inlinePerformIO)
+import qualified Data.ByteString.Internal as BSI 
+  ( unsafeCreate
+  , toForeignPtr
+  , inlinePerformIO
+  )
 import Control.Monad.IO.Class (MonadIO, liftIO)
-import Control.Exception ( IOException
-                         , SomeException
-                         , AsyncException
-                         , Exception
-                         , catch
-                         , try
-                         , throw
-                         , throwIO
-                         , mask_
-                         )
+import Control.Exception 
+  ( IOException
+  , SomeException
+  , AsyncException
+  , Exception
+  , catch
+  , try
+  , throw
+  , throwIO
+  , mask_
+  )
 import Control.Concurrent (ThreadId, forkIO)
 import Control.Concurrent.MVar (MVar, newEmptyMVar, takeMVar, putMVar)
 import GHC.IO (unsafeUnmask)
diff --git a/src/Network/Transport/Util.hs b/src/Network/Transport/Util.hs
--- a/src/Network/Transport/Util.hs
+++ b/src/Network/Transport/Util.hs
@@ -3,11 +3,12 @@
 -- Note: this module is bound to change even more than the rest of the API :)
 module Network.Transport.Util (spawn) where
 
-import Network.Transport ( Transport
-                         , EndPoint(..)
-                         , EndPointAddress
-                         , newEndPoint
-                         )
+import Network.Transport 
+  ( Transport
+  , EndPoint(..)
+  , EndPointAddress
+  , newEndPoint
+  )
 import Control.Concurrent (forkIO)
 import Control.Concurrent.MVar (newEmptyMVar, putMVar, takeMVar)