Reference Guide for the Model RT328 and Model RH348 ISDN Routers

Bandwidth on Demand

The Bandwidth on Demand (BOD) feature allows you to bundle both B channels in one logical connection. The second channel is added and subtracted dynamically according to traffic demand. The router uses the Bandwidth Allocation Control Protocol (BACP) and the Multilink Protocol (MP) in implementing bandwidth on demand.

The configuration of bandwidth on demand focuses on the Base Transmission Rate (BTR) and the

Maximum Transmission Rate (MTR). The relationship between BTR and MTR is shown in

Table 5-3.

Table 5-3.

Relationship Between BTR and MTR

 

 

 

 

 

 

BTR & MTR Setting

Number of Channels

Max Number of

Bandwidth on Demand

Used to Initiate Call

Channels Used

 

 

 

 

 

 

 

BTR = 64, MTR = 64

1

1

Off

BTR = 64, MTR = 128

1

2

On

BTR = 128, MTR = 128

2

2

Off

 

 

 

 

 

When the Bandwidth on Demand feature is enabled, a second channel is brought up if traffic on the initial channel is higher than the high Target Utility number for longer than the specified Add Persist value. Similarly, the second channel is dropped if the traffic level falls below the low Target Utility number for longer than the Subtract Persist value.

The Target Utility specifies the line utilization range at which you want the router to add or subtract bandwidth. The range is 30 to 64 Kbps. The parameters are separated by a hyphen ( - ).

For example, 30-60 means the add threshold is 60 Kbps and the subtract threshold is 30 Kbps. The router performs bandwidth on demand only if it initiates the call. Addition and subtraction are

based on the value set in the BOD Calculation field. If this field is set to Transmit or Receive, traffic in either direction is calculated to determine if a link should be added or dropped. Transmit uses only outgoing traffic to make this determination, and Receive uses only incoming traffic to make this determination.

5-6

Remote Node Configuration