Juniper JUNOS 10.1 - CONFIGURATION GUIDE 1-2010 Configuration Manual page 399

For a list of hierarchy levels at which you can include this statement, see rtvbr.
When configuring RTVBR, you can define the following shaping properties:
The peak and sustained rates can be from 33 Kbps through 542,526,792 bps.
Configuring ATM VBR
By default, ATM interfaces use UBR; that is, bandwidth utilization is unlimited. For
ATM1 and ATM2 IQ interfaces, you can configure non-real-time VBR, which supports
variable bit rate data traffic with average and peak traffic parameters. Compared to
RTVBR, non-real-time VBR is scheduled with a lower priority and with a larger SCR
limit, allowing it to recover bandwidth if it falls behind. Non-real-time VBR is suitable
for packet data transfers.
To define VBR on ATM1 and ATM2 IQ interfaces, include the
For a list of hierarchy levels at which you can include this statement, see vbr.
When configuring VBR, you can define the following shaping properties:
Specifying ATM1 Shaping Values
For ATM1 interfaces, you can specify the rates in bits per second or cells per second.
For OC3c interfaces, the highest rate is 135,631,698 bps (353,207.55 cps), which
corresponds to 100 percent of the available line rate. For OC12c interfaces, the
highest rate is 271,263,396 bps (706,415.09 cps), which corresponds to 50 percent
of the available line rate. Table 28 on page 331 lists some of the other rates you can
specify. If you specify a rate that is not listed, it is rounded to the nearest rate.
The exact number of values differs between OC12c and OC3c interfaces. OC12c
interfaces have about four times as many value increments as OC3c interfaces.
For OC12c rates between 1/2 of the line rate and 1/128 of the line rate, there are
128 steps between each 1/n value. This means that there is 128 steps between the
1/2 and 1/3 line rate values, and another 128 steps between 1/3 and 1/4 and so on.
For rates smaller than 1/127, there are (16,384 minus 127) or 16, 257 values. The
rtvbr peak rate sustained rate burst length;
Peak rate—Top rate at which traffic can burst.
Sustained rate—Normal traffic rate averaged over time.
Burst length—Maximum number of cells that a burst of traffic can contain. It
can be a value from 1 through 4000 cells.
vbr peak rate sustained rate burst length;
Peak rate—Top rate at which traffic can burst.
Sustained rate—Normal traffic rate averaged over time.
Burst length—Maximum number of cells that a burst of traffic can contain. It
can be a value from 1 through 4000 cells.
Chapter 13: Configuring ATM Interfaces
vbr statement:
Defining the ATM Traffic-Shaping Profile
329