cra

Constant Rate Allocation (CRA)

Table of content

• Constant Rate Allocation (CRA)
  • OpenSAND exploitation
    • Probes
  • OpenSAND software design

Constant Rate Allocation (CRA) is one of the types of allocation available in OpenSAND (consult the DAMA page for more information).

A terminal is allocated the CRA capacity on each allocation loop, without the need of making capacity requests.

OpenSAND exploitation

If a terminal is used configured to use DAMA (refer to the DAMA page for more information), then it will always use CRA, up to the capacity specified by constant_rate_allocation. This value can be configured in the dvb_rcs_tal section of the terminal configuration, on the Advanced Configurations window.

By default, each terminal has a Constant Rate Allocation of 100 kbits/s.

Probes

There are several probes that allow the user to inspect the CRA allocations on the gateway:

• STX_allocation.CRA_allocation: the CRA allocation for the STX, in kbits/s.
• Spot_X.NCC.CRA_allocated: the total CRA allocation for the Spot X, in kbits/s.

On the terminal side, there are no probes specific to CRA, and CRA can only be observed through the Total Allocation probe: while there is no traffic, and therefore, no capacity requests, the total allocation is equal to the CRA + FCA.

OpenSAND software design

CRA allocations are computed on the gateway by the DamaCtrl. They are the first type of allocation to be computed.