Networking methods Delivery methods
XBee®-PRO 900HP/XSC RF Modules
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1. The source node does not have a route to the requested destination.
2. A route fails. This happens when the source node uses up its network retries without receiving
an ACK.
Route discovery begins by the source node broadcasting a route request (RREQ). We call any router
that receives the RREQ and is not the ultimate destination, an intermediate node.
Intermediate nodes may either drop or forward a RREQ, depending on whether the new RREQ has a
better route back to the source node. If so, the node saves, updates and broadcasts the RREQ.
When the ultimate destination receives the RREQ, it unicasts a route reply (RREP) back to the source
node along the path of the RREQ. It does this regardless of route quality and regardless of how many
times it has seen an RREQ before.
This allows the source node to receive multiple route replies. The source node selects the route with
the best round trip route quality, which it uses for the queued packet and for subsequent packets with
the same destination address.
DigiMesh throughput
Throughput in a DigiMesh network can vary due to a number of variables, including:
n The number of hops.
n If you enable or disable encryption.
n Sleeping end devices.
n Failures and route discoveries.
The following table shows the results of our empirical testing of throughput performance in a robust
operating environment (low interference).
The results apply to the 200 kb/s version with a 115.2 kb/s serial data rate.
Configuration Data throughput
Mesh unicast, 1 hop, encryption disabled 91.0 kb/s
Mesh unicast, 3 hop, encryption disabled 32.5 kb/s
Mesh unicast, 6 hop, encryption disabled 16.7 kb/s
Mesh unicast, 1 hop, encryption enabled 89.3 kb/s
Mesh unicast, 3 hop, encryption enabled 32.2 kb/s
Mesh unicast, 6 hop, encryption enabled 16.1 kb/s
Note We made the data throughput measurements by setting the serial interface rate to 115200 b/s,
and measuring the time to send 100,000 bytes from source to destination. During the test, no route
discoveries or failures occurred.
Transmission timeouts
When a device in API operating mode receives a Transmit Request (0x10, 0x11) frame, or a device in
Transparent operating mode meets the packetization requirements (RO, RB), the time required to
route the data to its destination depends on:
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