Specifications

UHP-1000 SATELLITE ROUTER

INSTALLATION AND OPERATION MANUAL, V. 2.5

(SW VERSION 2.5.X)

Basic principles of TS operation:

 Tailoring committed information rate (CIR) for each stream

 If there is a free bandwidth on the modulator and streams are allowed to exceed CIR, TS will extend

bandwidths of those streams that are overloaded

 Expansion proportional to CIR

 Expansion of streams is effected smoothly, proportionally to the free bandwidth of the modulator so as to

avoid overloads, narrowing is effected more aggressively based on the same reason

 If modulator load approaches its limit, TS narrows the bandwidths of exceeding streams to lower the

modulator load or to the values of their CIRs

Calculation and correction of the stream bandwidths is made every second, and that is why TS responds

dynamically to the behavior and requirements of the network.

Examples of TS operation:

Two streams share a 800 Kbit/s channel. CIR of the green stream is 200 Kbit/s, that of the red one – 400 Kbit/s.

Maximum stream bit rates are not limited. The blue line stands for general load of the channel. Dashed line means

the desired stream bit rates.

Figure 22 Example of Traffic Shaper operation

By points (Figure 22):

 Green traffic begins entering at 300 Kbit/s. This is within CIR limits and hence TS does not delay packets.

 Incoming green traffic bandwidth increases three-fold – up to 600K. Traffic begins to be delayed since the

stream bandwidth is insufficient. As the load of the general channel is low, TS begins to smoothly expand

green stream bandwidth until its overload is eliminated. Stream rate of increase is proportional to the

”Slope Factor” which is set in the TS configuration.

 Green stream bandwidth is stabilized at 600K to pass the traffic without delay.

 Red traffic starts with 700K bandwidth. Gets immediately 400K (CIR). The channel gets overloaded. TS

almost immediately narrows the green stream bandwidth up to CIR=400К to remove modulator overload.

Since both streams are overloaded and want to get a wider bandwidth, a fair (proportional to their CIR)

distribution of the bandwidth between them is initiated.

 The bandwidth is divided in proportion of 33% to the red stream (CIR=400K) and 66% to the green stream

(CIR=200K). Channel load is close to 100%.

 Green traffic reduces to 250K. Nothing happens since its bandwidth is still wider than CIR.

 Green traffic ceases. Modulator load drops and TS starts to expand overloaded red stream.

 Red stream gets stabilized at 700K to transmit traffic without delay.

In this example adaptation of IP-protocols to the delay is not taken account of, otherwise the example would

be too complicated but the algorithm is designed for this adaptation.

TS does not track the situation when the sum of assigned CIRs exceeds the modulator bit rate. In this case TS

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