User's Manual Part 1
Release8OverviewofCycloneNetworks
Issue2,November2007 Draft5forRegulatoryReview 86
In this example case, the derived 1,167-kbps uplink and 5,833-kbps downlink MIR sum to
the fixed 7,000-kbps aggregate cap of the Canopy SM.
7.1.8 CommittedInformationRate
The Committed Information Rate (CIR) capability feature enables the service provider to
guarantee to any subscriber that bandwidth will never decrease to below a specified
minimum, unless CIR is oversubscribed. Bandwidth can be, and typically will be, higher
than the minimum, but this guarantee helps the WISP to attract and retain subscribers.
In BAM Release 2.1 and in Prizm Release 2.0, CIR configuration is supported as follows:
• The GUI allows you to view and change CIR configuration parameters per SM.
• When an SM successfully registers and authenticates, if BAM or Prizm has CIR
configuration data for the SM, then messages make the CIR configuration
available to the SM, depending on the Configuration Source setting. (See
Setting
the Configuration Source
on Page 295.)
• The operator can disable the CIR feature in the SM without deleting the CIR
configuration data.
7.1.9 BandwidthfromtheSMPerspective
In the Canopy SM, normal web browsing, e-mail, small file transfers, and short streaming
video are rarely rate limited with practical bandwidth management (QoS) settings. When
the SM processes large downloads such as software upgrades and long streaming video
or a series of medium-size downloads, the bucket rapidly drains, the burst limit is
reached, and some packets are delayed. The subscriber experience is more affected in
cases where the traffic is more latency sensitive.
Example download times for various arbitrary tiers of service are shown in
Table 55 on
Page
388 and Table 56 on Page 389.
7.1.10 InteractionofBurstAllocationandSustainedDataRateSettings
If the Burst Allocation is set to 1200 kb and the Sustained Data Rate is set to 128 kbps, a
data burst of 1000 kb is transmitted at full speed because the Burst Allocation is set high
enough. After the burst, the bucket experiences a significant refill at the Sustained Data
Rate. This configuration uses the advantage of the settable Burst Allocation.
If both the Burst Allocation and the Sustained Data Rate are set to 128 kb, a burst is
limited to the Burst Allocation value. This configuration does not take advantage of the
settable Burst Allocation.
If the Burst Allocation is set to 128 kb and the Sustained Data Rate is set to 256 kbps, the
actual rate will be the burst allocation (but in kbps). As above, this configuration does not
take advantage of the settable Burst Allocation.
7.1.11 High‐priorityBandwidth
To support low-latency traffic such as VoIP (Voice over IP) or video, the Cyclone system
implements a high-priority channel. This channel does not affect the inherent latencies in
the Cyclone system but allows high-priority traffic to be immediately served. The high-
priority pipe separates low-latency traffic from traffic that is latency tolerant, such as
standard web traffic and file downloads.