===========================
Configuration file overview
===========================
**Bison Router** is configured according to the configuration file. To start configuring, create ``/etc/bisonrouter/brouter.conf``

.. code-block:: none

      nano /etc/bisonrouter/brouter.conf

The configuration file consists of two sections:

- **Startup**. This section is intended for a one-time initial setup and cannot be changed later. It includes basic settings of ports and receive queues.

- **Runtime**. This section is intended for further detailed configuration, and can be changed as needed even after **Bison Router** has started.

**Example**

The **Bison Router** configuration file example:

.. code-block:: none

  startup {
      # total number of mbufs
      sysctl set mbuf 32768

      port 0 mtu 1500 tpid 0x8100 state enabled
      port 1 mtu 1500 tpid 0x8100 state enabled

      rx_queue port 0 queue 0 lcore 1
      rx_queue port 0 queue 1 lcore 2
      rx_queue port 0 queue 2 lcore 3

      rx_queue port 1 queue 0 lcore 3
      rx_queue port 1 queue 1 lcore 2
      rx_queue port 1 queue 2 lcore 1

      sysctl set global_packet_counters 1
  }
  
  runtime {
      vif add name p0 port 0 type untagged
      ip addr add 10.0.0.1/24 dev p0

      vif add name p1 port 1 type untagged
      ip addr add 10.0.1.1/24 dev p1

      ip route add 0.0.0.0/0 via 10.0.1.2 src 10.0.1.1
  }

Important to remember while working with the configuration file:

.. note:: 
 If you make some adjustments using the command line, you will also need to make changes in the configuration file and save them to apply.
.. note::
 It is important to follow the parameter sequence defined in this instruction. An exception is made for optional parameters specified in square brackets []. They can be omitted.
.. note::
      A section line is considered as a single command. The # character is used to comment an entire line.