ND SatCom SKYWAN IDU 1070, Manual

Page: 43 / 154

2010-10-26 Network Design and Engineering Guide 39
General Carrier Design
Essential SkyWAN
®
Satellite Link Layer Features
Scenario 3
Both IDU1 and IDU2 are configured for stream mode Stream within Guaranteed Through-
put . The traffic mix (see figure 2-22) consists of:
- A non real-time IP based PC application with a bidirectional bandwidth requirement of 128
kbps between these two stations.
- Additionally 3 parallel voice calls served by Sky WAN
®
FAD real-time service should be ac-
tive between the stations.
Figure 2-22 Throughput Scenario 3
Effect
First two parallel voice calls are set up between the stations. The necessary streaming slot for
this service must be taken out of the respective private bandwidth pools. If now additionally a
non real-time bidirectional PC application is set up, the bandwidth for this service is still guar-
anteed because the required 5 slots for each station are still available in the private pool. If how-
ever an additional voice call is set up between the stations the additional streaming slot again
must be taken out of the private pool, leaving only four slots for other services. Note, that real-
time services have always priority over non real-time services.
As long as the network is not congested, the PC application may still be served with sufficient
bandwidth by allocating an unrequested slot from the common bandwidth pool. However there
is no guarantee for this additional slot and the allocation may be withdrawn at any time by the
master in case of network congestion.
Strictly speaking the guarantee and the limit for IDU1 and IDU2 in this scenario is 6 streaming
slots for each station. For dynamic slots there is no fixed guarantee (but also no specific limit),
only at times when the stations are not using the full private bandwidth for real-time services,
the remaining part of the private pool would be guaranteed for non real-time services.