GE MDS entraNET 2400, Technical Manual

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05-4055A01, Rev. E MDS entraNET Technical Manual 161
• The number of bytes they can fit into a hop, depending on hop
time, is:
Included in the byte count is 9 bytes of overhead per packet. So,
at 7 ms without FEC, a 1000 byte packet requires 1009 bytes
split into 45 bytes/hop, or 23 hops. 1026 bytes of data also
requires 23 hops; however, a 1027-byte data packet requires 24
hops.
• If any transceiver in your network is connected to a large LAN,
such as may be found in a large office complex, there might be
undesired multicast or broadcast traffic over the air.
3. Station-to-Station Traffic
• When sending frames from one remote endpoint to another
remote endpoint using an AP transceiver (see Figure 6-7 ),
throughput is halved at best. This is because all frames must go
through the AP. Therefore, in the previous 100 byte UDP
example, the number of over-the-air bytes is 380 bytes
(190 bytes times 2) if the frame must go station to station.
Invisible place holder
Figure 6-7. Endpoint-to-Endpoint Communication Using an AP
4. Interference has a direct correlation to throughput:
• Interference could be caused by any unnecessary traffic on the
network from unrelated activities, or radio interference.
Table 6-1. Number of bytes per hop
Hop time
(MS) FEC Bytes/hop
7 45
7 FEC 11
14 139
14 FEC 59
28 324
28 FEC 151
192.168.0.50
RTU
192.168.0.4
RTU
Terminal
or Computer
192.168.0.10
192.168.0.1
LAN
COM 1
COM
2
PWR
LINK
LIN
K
ETH
CO M1
PW
R LIN
K
ETH
CO M1
PW
R
Message Source
Access Point
Remote
Remote
Message Destination