User's Manual

3 Detailed Description
APCD-LM043-4.0 47
• Pings (interval is typically 1 second): WaveRider recommends the operator avoid
running applications that generate a lot of pings, such as What’s Up Gold.
• Network gaming (interval is typically 0.25 seconds): WaveRider can provide a GOS
class for managing this kind of traffic if specific end users are running this type of
application.
• SNMP poll (interval is typically 30 seconds): This traffic is usually generated by the
operator. WaveRider recommends increasing the SNMP poll interval to a large value,
for example, greater than one hour and, if possible, that the SNMP application not poll
all EUMs in the same short interval.
TIP: Consult WaveRider for a special GOS Configuration File to
limit the impact of these atypical applications for specific EUMs.
Network Monitoring
Some applications send packets to each host on the network, usually to determine whether
the host is accessible and/or functioning. These applications, which may be run by the system
operator, cause EUMs that otherwise would not be associated to become associated. Often,
the additional load from applications of this type can even exceed the end-user traffic load on
the system. Since these applications tend to be periodic, the load is presented to the system
regularly over an indefinite period. Also, with large networks, application polling may soon
exceed the maximum number of associations. In this case, the application may not be able to
receive responses from some EUMs, presenting the operator with misleading status
information. This group includes the following applications:
• SNMP polling: As noted above, WaveRider recommends increasing the SNMP poll
interval to a large value, for example, greater than one hour, and staggering polls to
groups of EUMs.
• SNMP service discovery: Service discovery is not required for management of the
LMS4000 900 MHz Radio Network.
• Ping scripts,suchasWhat’s Up Gold: WaveRider recommends obtaining a tool to
stagger the pings.
Since the network operator controls most of the above applications, WaveRider recommends
limiting or at least delaying their use until non-busy hours.
Voice Over IP (VoIP)
Voice over IP (as opposed to streaming audio or video) requires small packets to be sent at
very short intervals — usually around 20 ms — with very little latency allowed in either
direction. While the LMS4000 900 MHz Radio Network may be able to support this level,
either as a guaranteed grade of service class parameter or on a best effort basis, VoIP
applications result in a high per packet overhead on the radio channel. This overhead and the
requirement for low latency mean the VoIP call occupies about 10% of the available bandwidth
for the duration of the call. It obviously does not take very many VoIP users to significantly
affect system performance. Also, unless this grade of service guarantee is given, the quality of