diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index 14406f5e70..671ca1a7ec 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -326,6 +326,17 @@ def event_from_pdu_json(pdu_json, outlier=False):
     elif depth > MAX_DEPTH:
         raise SynapseError(400, "Depth too large", Codes.BAD_JSON)
 
+    dtab = pdu_json.get("unsigned", {}).pop("dtab", None)
+
+    if dtab:
+        pdu_json.setdefault("unsigned", {})["destinations"] = {
+            dest: cost
+            for cost, destinations in dtab
+            for dest in destinations
+        }
+
+    logger.info("Unmangled event to: %s", pdu_json)
+
     event = FrozenEvent(
         pdu_json
     )
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index efb1360edb..d3aee9e953 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -247,7 +247,16 @@ class FederationServer(FederationBase):
         )
 
         if hasattr(transaction, "edus"):
-            for edu in (Edu(**x) for x in transaction.edus):
+            logger.info("Got edus: %s", transaction.edus)
+
+            edus = []
+            for x in transaction.edus:
+                try:
+                    edus.append(Edu(**x))
+                except Exception:
+                    logger.exception("Failed to handle EDU: %s", x)
+
+            for edu in edus:
                 yield self.received_edu(
                     origin,
                     edu.edu_type,
diff --git a/synapse/federation/transaction_queue.py b/synapse/federation/transaction_queue.py
index 9e28bde32c..f375034d5a 100644
--- a/synapse/federation/transaction_queue.py
+++ b/synapse/federation/transaction_queue.py
@@ -587,8 +587,10 @@ class TransactionQueue(object):
                     pdu_span_references.append(opentracing.follows_from(span.context))
 
                 # END CRITICAL SECTION
-
-                with self.tracer.start_span('_send_new_transaction', references=pdu_span_references) as span:
+                span = self.tracer.start_span(
+                    '_send_new_transaction', references=pdu_span_references,
+                )
+                with span:
                     span.set_tag("destination", destination)
 
                     success = yield self._send_new_transaction(
@@ -629,7 +631,7 @@ class TransactionQueue(object):
                 destination,
                 e,
             )
-            for p, _ in pending_pdus:
+            for p, _, _ in pending_pdus:
                 logger.info("Failed to send event %s to %s", p.event_id,
                             destination)
         finally:
@@ -672,7 +674,8 @@ class TransactionQueue(object):
 
     @measure_func("_send_new_transaction")
     @defer.inlineCallbacks
-    def _send_new_transaction(self, destination, pending_pdus, pending_edus, span, pdu_spans):
+    def _send_new_transaction(self, destination, pending_pdus, pending_edus,
+                              span, pdu_spans):
 
         # Sort based on the order field
         pending_pdus.sort(key=lambda t: t[1])
@@ -749,6 +752,9 @@ class TransactionQueue(object):
             code = e.code
             response = e.response
 
+            span.set_tag("error", True)
+            span.log_kv({"error": e})
+
             if e.code in (401, 404, 429) or 500 <= e.code:
                 logger.info(
                     "TX [%s] {%s} got %d response",
@@ -796,6 +802,7 @@ class TransactionQueue(object):
         """
         # XXX: Hook for routing shenanigans
         if "error" in response:
+            span.set_tag("error", True)
             span.log_kv({
                 "error.kind": "pdu",
                 "response.error": response["error"],
@@ -847,6 +854,7 @@ class TransactionQueue(object):
             destination, txn_id, pdu.event_id,
         )
 
+        span.set_tag("error", True)
         span.log_kv({
             "error.kind": "transaction",
         })
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index b5f9d9ebb8..072849d871 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -20,8 +20,6 @@ import re
 import opentracing
 from opentracing.ext import tags
 
-import six
-
 from twisted.internet import defer
 
 import synapse
@@ -296,17 +294,22 @@ class BaseFederationServlet(object):
                     logger.warn("authenticate_request failed: %s", e)
                     raise
 
-                if origin:
-                    span.set_tag("origin", origin)
-                    with ratelimiter.ratelimit(origin) as d:
-                        yield d
+                try:
+                    if origin:
+                        span.set_tag("origin", origin)
+                        with ratelimiter.ratelimit(origin) as d:
+                            yield d
+                            response = yield func(
+                                origin, content, request.args, *args, **kwargs
+                            )
+                    else:
                         response = yield func(
                             origin, content, request.args, *args, **kwargs
                         )
-                else:
-                    response = yield func(
-                        origin, content, request.args, *args, **kwargs
-                    )
+                except Exception as e:
+                    span.set_tag("error", True)
+                    span.log_kv({"error": e})
+                    raise
 
                 span.set_tag(tags.HTTP_STATUS_CODE, response[0])
 
diff --git a/synapse/federation/units.py b/synapse/federation/units.py
index 6b329f26b4..20e5922c74 100644
--- a/synapse/federation/units.py
+++ b/synapse/federation/units.py
@@ -17,6 +17,7 @@
 server protocol.
 """
 
+import itertools
 import logging
 
 from synapse.util.jsonobject import JsonEncodedObject
@@ -24,6 +25,9 @@ from synapse.util.jsonobject import JsonEncodedObject
 logger = logging.getLogger(__name__)
 
 
+BUCKETS = [0, 50, 100, 200, 350, 500, 750, 1000, 2000, 5000, 10000, 100000]
+
+
 class Edu(JsonEncodedObject):
     """ An Edu represents a piece of data sent from one homeserver to another.
 
@@ -122,6 +126,20 @@ def _mangle_pdu(pdu_json):
     pdu_json["auth_events"] = list(_strip_hashes(pdu_json["auth_events"]))
     pdu_json["prev_events"] = list(_strip_hashes(pdu_json["prev_events"]))
 
+    destinations = pdu_json["unsigned"].pop("destinations", None)
+    if destinations:
+        new_destinations = {}
+        for dest, cost in destinations.items():
+            for first, second in pairwise(BUCKETS):
+                if first <= cost <= second:
+                    b = first if cost - first < second - cost else second
+                    new_destinations.setdefault(b, []).append(dest)
+                    break
+            else:
+                new_destinations.setdefault(b[-1], []).append(dest)
+
+        pdu_json["unsigned"]["dtab"] = list(new_destinations.items())
+
     logger.info("Mangled PDU: %s", pdu_json)
 
     return pdu_json
@@ -132,3 +150,10 @@ def _strip_hashes(iterable):
         (e, {})
         for e, hashes in iterable
     )
+
+
+def pairwise(iterable):
+    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
+    a, b = itertools.tee(iterable)
+    next(b, None)
+    return zip(a, b)
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 172b6947d4..7b23757282 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -347,7 +347,7 @@ class PresenceHandler(object):
         """Checks the presence of users that have timed out and updates as
         appropriate.
         """
-        #logger.info("Handling presence timeouts")
+        # logger.info("Handling presence timeouts")
         now = self.clock.time_msec()
 
         try:
@@ -626,6 +626,7 @@ class PresenceHandler(object):
         Args:
             states (list(UserPresenceState))
         """
+        return
         self.federation.send_presence(states)
 
     @defer.inlineCallbacks
@@ -816,6 +817,7 @@ class PresenceHandler(object):
         if self.is_mine(observed_user):
             yield self.invite_presence(observed_user, observer_user)
         else:
+            return
             yield self.federation.send_edu(
                 destination=observed_user.domain,
                 edu_type="m.presence_invite",
@@ -836,6 +838,7 @@ class PresenceHandler(object):
         if self.is_mine(observer_user):
             yield self.accept_presence(observed_user, observer_user)
         else:
+            return
             self.federation.send_edu(
                 destination=observer_user.domain,
                 edu_type="m.presence_accept",
diff --git a/synapse/handlers/receipts.py b/synapse/handlers/receipts.py
index 4c2690ba26..8f3504583d 100644
--- a/synapse/handlers/receipts.py
+++ b/synapse/handlers/receipts.py
@@ -147,6 +147,8 @@ class ReceiptsHandler(BaseHandler):
 
                 logger.debug("Sending receipt to: %r", remotedomains)
 
+                return
+
                 for domain in remotedomains:
                     self.federation.send_edu(
                         destination=domain,
diff --git a/synapse/handlers/typing.py b/synapse/handlers/typing.py
index 2af164a142..da8cfe0440 100644
--- a/synapse/handlers/typing.py
+++ b/synapse/handlers/typing.py
@@ -86,7 +86,7 @@ class TypingHandler(object):
         self._room_typing = {}
 
     def _handle_timeouts(self):
-        #logger.info("Checking for typing timeouts")
+        # logger.info("Checking for typing timeouts")
 
         now = self.clock.time_msec()
 
@@ -231,6 +231,7 @@ class TypingHandler(object):
             for domain in set(get_domain_from_id(u) for u in users):
                 if domain != self.server_name:
                     logger.debug("sending typing update to %s", domain)
+                    return
                     self.federation.send_edu(
                         destination=domain,
                         edu_type="m.typing",
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 2830970e22..729e6e9924 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -385,7 +385,8 @@ class MatrixFederationHttpClient(object):
                                     request_deferred,
                                 )
                         except Exception as e:
-                            child_span.set_tag("error", str(e))
+                            child_span.set_tag("error", True)
+                            child_span.log_kv({"error": e})
                             raise
 
                         child_span.set_tag(tags.HTTP_STATUS_CODE, response.code)
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 904f9305ee..187ca45ac9 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -402,6 +402,12 @@ class EventsStore(StateGroupWorkerStore, EventFederationStore, EventsWorkerStore
                                 # No change in extremities, so no change in state
                                 continue
 
+                            logger.info(
+                                "Forward extremities for %s: %s -> %s",
+                                room_id, latest_event_ids, new_latest_event_ids,
+                            )
+                            logger.info("Events: %s", [e.event_id for e, _ in ev_ctx_rm])
+
                             # there should always be at least one forward extremity.
                             # (except during the initial persistence of the send_join
                             # results, in which case there will be no existing