doc/user/kernel.rst

   1 .. _kernel-interface:
   2
   3 ****************
   4 Kernel Interface
   5 ****************
   6
   7 There are several different methods for reading kernel routing table
   8 information, updating kernel routing tables, and for looking up interfaces.
   9
  10 - ioctl
  11      This method is a very traditional way for reading or writing kernel
  12      information. `ioctl` can be used for looking up interfaces and for
  13      modifying interface addresses, flags, mtu settings and other types of
  14      information. Also, `ioctl` can insert and delete kernel routing table
  15      entries. It will soon be available on almost any platform which zebra
  16      supports, but it is a little bit ugly thus far, so if a better method is
  17      supported by the kernel, zebra will use that.
  18
  19 - sysctl
  20      This is a program that can lookup kernel information using MIB (Management
  21      Information Base) syntax. Normally, it only provides a way of getting
  22      information from the kernel. So one would usually want to change kernel
  23      information using another method such as `ioctl`.
  24
  25 - proc filesystem
  26      This is a special filesystem mount that provides an easy way of getting
  27      kernel information.
  28
  29 - routing socket / Netlink
  30      On recent Linux kernels (2.0.x and 2.2.x), there is a kernel/user
  31      communication support called `Netlink`. It makes asynchronous communication
  32      between kernel and FRR possible, similar to a routing socket on BSD systems.
  33
  34      Before you use this feature, be sure to select (in kernel configuration) the
  35      kernel/Netlink support option 'Kernel/User network link driver' and 'Routing
  36      messages'.
  37
  38      Today, the :file:`/dev/route` special device file is obsolete.  Netlink
  39      communication is done by reading/writing over Netlink socket.
  40
  41      After the kernel configuration, please reconfigure and rebuild FRR.  You can
  42      use Netlink as a dynamic routing update channel between FRR and the kernel.