diff --git a/chronosim/chronosim.nim b/chronosim/chronosim.nim
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+# Copyright (c) 2023 Status Research & Development GmbH
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+# ChronoSim: simulation/emulation wrapper around Chronos
+
+import
+  std/[tables, deques, random],
+  chronos,
+  chronicles
+
+logScope:
+  topics = "ChronoSim"
+
+const
+  timeWarp = 1
+  emulateDatagram = true
+
+# chronos uses SomeIntegerI64. We shoudl be more specific here to override
+proc milliseconds*(v: int): Duration {.inline.} =
+  chronos.milliseconds(v * timeWarp)
+
+proc seconds*(v: int): Duration {.inline.} =
+  chronos.seconds(v * timeWarp)
+
+when(emulateDatagram): #enable network emulator
+  type
+    DatagramCallback* = proc(transp: DatagramTransport,
+                            remote: TransportAddress): Future[void] {.
+                        gcsafe, raises: [Defect].}
+
+    DatagramTransport* = ref object
+      udata*: pointer                 # User-driven pointer
+      local: TransportAddress         # Local address
+      callback: DatagramCallback      # Receive data callback
+      ingress: Deque[seq[byte]]
+      egress: Deque[(TransportAddress, seq[byte])]  # simple FIFO for now
+
+  var network = initTable[Port, DatagramTransport]()
+
+  proc `$`*(transp: DatagramTransport): string =
+    $transp.local
+
+  proc recvFrom[T](transp: DatagramTransport, remote: TransportAddress,
+              msg: sink seq[T], msglen = -1) =
+    trace "recv:",  src = remote, dst = transp.local
+    {.gcsafe.}:
+      transp.ingress.addLast(msg)
+      # call the callback on remote
+      asyncCheck transp.callback(transp, remote)
+
+  proc getLatency(src: TransportAddress, dst: TransportAddress) : Duration =
+    50.milliseconds
+
+  proc getLoss(src: TransportAddress, dst: TransportAddress) : float =
+    0.0
+  proc getLineTime(transp: DatagramTransport, msg: seq[byte]) : Duration =
+    # let bandwith = transp.bandwidth
+    let bandwidth = 100 # Bytes/ms = KB/sec
+    (msg.len div bandwidth).milliseconds
+
+  proc sendTo*[T](transp: DatagramTransport, remote: TransportAddress,
+              msg: sink seq[T], msglen = -1) {.async.} =
+    trace "send:", src = transp.local, dst = remote
+
+    #transp.egress.addLast(remote, msg)
+    #await sleepAsync(getLineTime(transp, msg))
+
+    if rand(1.0) < getLoss(transp.local, remote):
+      return
+
+    await sleepAsync(getLatency(transp.local, remote))
+    {.gcsafe.}:
+      network[remote.port].recvFrom(transp.local, msg)
+
+  proc getMessage*(t: DatagramTransport,): seq[byte] {.
+      raises: [Defect, CatchableError].} =
+    #echo "getMessage "
+    t.ingress.popFirst()
+
+  proc close*(transp: DatagramTransport) =
+    debug "close"
+
+  proc closed*(transp: DatagramTransport): bool {.inline.} =
+    result = false
+
+  proc closeWait*(transp: DatagramTransport) {.async.} =
+    debug "closeWait "
+
+  proc getUserData*[T](transp: DatagramTransport): T {.inline.} =
+    ## Obtain user data stored in ``transp`` object.
+    result = cast[T](transp.udata)
+
+  proc newDatagramTransport*[T](cbproc: DatagramCallback,
+                            udata: ref T,
+                            local: TransportAddress = AnyAddress,
+                            ): DatagramTransport {.
+      raises: [Defect, CatchableError].} =
+    debug "new"
+    result = DatagramTransport()
+    GC_ref(udata)
+    result.udata = cast[pointer](udata)
+    result.local = local
+    result.callback = cbproc
+    {.gcsafe.}:
+      network[local.port] = result
+
+export seconds, milliseconds
+export TransportAddress, initTAddress
+export async, sleepAsync, complete, await
+export Future, FutureBase, newFuture, futureContinue
+export TransportOsError
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