diff --git a/site/kube-addon.md b/site/kube-addon.md
index eed3c89d..7dc08df4 100644
--- a/site/kube-addon.md
+++ b/site/kube-addon.md
@@ -144,3 +144,8 @@ The list of variables you can set is:
 * WEAVE\_EXPOSE\_IP - set the IP address used as a gateway from the
   Weave network to the host network - this is useful if you are
   configuring the addon as a static pod.
+* WEAVE\_MTU - Weave Net defaults to 1410 bytes, but you can set a
+  smaller size if your underlying network has a tighter limit, or set
+  a larger size for better performance if your network supports jumbo
+  frames - see [here](/site/using-weave/fastdp.md#mtu) for more
+  details.
diff --git a/site/using-weave/fastdp.md b/site/using-weave/fastdp.md
index 619703b1..9f4bbbcc 100644
--- a/site/using-weave/fastdp.md
+++ b/site/using-weave/fastdp.md
@@ -42,7 +42,7 @@ Where fastdp indicates that fast datapath is being used on a connection. If fast
     $ weave status connections
     <- 192.168.122.25:54782  established sleeve 8a:50:4c:23:11:ae(ubuntu1204)
 
-###Packet size (MTU)
+###<a name="mtu"></a>Packet size (MTU)
 
 The Maximum Transmission Unit, or MTU, is the technical term for the
 limit on how big a single packet can be on the network. Weave Net
@@ -51,8 +51,9 @@ underlying network has a tighter limit, or set a larger size for
 better performance.
 
 The underlying network must be able to deliver packets of the size
-specified plus overheads of around 50 bytes.  This requirement applies
-to _every path_ between peers.
+specified plus overheads of around 50 bytes, or else Weave Net will
+fall back to Sleeve for that connection.  This requirement applies
+to _every path_ between peers. 
 
 To specify a different MTU, before launching Weave Net set the
 environment variable `WEAVE_MTU`.  For example, for a typical "jumbo