User's Manual

PMP 450 Operations Guide
Traffic Scheduling
pmp-0049 (September 2012)
2-5
This tab in the AP sets the priorities for the various packets in the downstream (sent from the public
network). This tab in the SM sets the priorities for the various packets in the upstream (sent to the
public network).
Typically, some SMs attach to older devices that use the ToS byte as originally formatted, and others
to newer devices that use the DSCP field. The default values in the Diffserv tab allow your modules to
prioritize traffic from the older devices roughly the same as they traditionally have. However, these
default values may result in more high-priority traffic as DSCP fields from the newer devices are read
and handled. So, after making any changes in the Diffserv tab, carefully monitor the high-priority
channel for high packet rates
in SMs that you have identified as those to initially set and watch.
across your network when you have broadly implemented Code Point values, such as via SNMP.
Traffic Scheduling
The characteristics of traffic scheduling in a sector are summarized in Table 2.
Table 2 Characteristics of traffic scheduling
Category
Factor
Treatment
Throughput
Aggregate throughput, less
additional overhead
90 Mbps
Latency
Number of frames required
for the scheduling process
1
Round-trip latency
≈ 6 ms
AP broadcast the download
schedule
No
High-
priority
Channel
Allocation for uplink high-
priority traffic on amount of
high-priority traffic
Dynamic, based
on amount of
high-priority
traffic
Allocation for downlink high-
priority traffic on amount of
high-priority traffic
Dynamic, based
on amount of
high-priority
traffic
Order of transmission
Other high-priority
Other low-priority
Power requirements affect the recommended maximums for power cord length feeding the CMMmicro
or CMM4. See the dedicated user guide that supports the CMM that you are deploying. However, the
requirements do not affect the maximums for the CMM2.