User's Manual

3 Detailed Description
22 APCD-LM043-4.0
Lightning Arrestor
A lightning arrestor is required at the EUM only if an outdoor antenna is used.
3.4 Basic Operation
3.4.1 LMS4000 Transmission Concept
Conceptually, the LMS4000 900 MHz Radio Network can be thought of as an Ethernet switch
with a built-in router, as shown in Figure 14.
Figure 14 LMS4000 Transmission Concept
In the above diagram, the “switch” consists of the CCU and EUM physical, MAC, and IP
bridging layers, and the 900 MHz link between them. IP packets originating from any host in
the radio subnet (EUM or PC, for example), which are destined for a host that is also in the
radio subnet, are “switched” by the CCU directly to that host. IP packets originating from any
host in the radio subnet, which are destined for a host outside the radio subnet, are “switched”
to the CCU router for routing to the destination host.
IP packets coming into the CCU Ethernet port, which are destined to a host in the radio
subnet, are routed to the “switch” and “switched” to the host.
3.4.2 CCU and EUM Configuration
When CCUs and EUMs are shipped from the factory, they are pre-programmed with a set of
factory default settings. Some of these default settings must be modified before the system
can pass traffic. These basic settings are listed Table 3 and Ta ble 4. Once your system is
carrying traffic, you can configure the more advanced CCU and EUM features and functions,
which are also listed in these tables.
EUM Host
PC
EUM Host
End-user
LAN
PC
EUM Host
CCU Router
Application
CCU Ethernet port
"Switch"
CCU