T4977: Add Babel routing protocol

Documentation for https://github.com/vyos/vyos-1x/pull/1800.

1 files changed, 210 insertions, 0 deletions

diff --git a/docs/configuration/protocols/babel.rst b/docs/configuration/protocols/babel.rst
new file mode 100644
index 00000000..58436178
--- /dev/null
+++ b/docs/configuration/protocols/babel.rst
@@ -0,0 +1,210 @@
+.. _babel:
+
+####
+Babel
+####
+
+Babel is a modern routing protocol designed to be robust and efficient
+both in ordinary wired networks and in wireless mesh networks.
+By default, it uses hop-count on wired networks and a variant of ETX
+on wireless links, It can be configured to take radio diversity into account
+and to automatically compute a link's latency and include it in the metric.
+It is defined in :rfc:`8966`.
+
+Babel a dual stack protocol.
+A single Babel instance is able to perform routing for both IPv4 and IPv6.
+
+General Configuration
+---------------------
+
+VyOS does not have a special command to start the Babel process.
+The Babel process starts when the first Babel enabled interface is configured.
+
+.. cfgcmd:: set protocols babel interface <interface>
+
+  This command specifies a Babel enabled interface by interface name. Both
+  the sending and receiving of Babel packets will be enabled on the interface
+  specified in this command.
+
+Optional Configuration
+----------------------
+
+.. cfgcmd:: set protocols babel parameters diversity
+
+  This command enables routing using radio frequency diversity.
+  This is highly recommended in networks with many wireless nodes.
+
+   .. note:: If you enable this, you will probably want to
+      set diversity-factor and channel below.
+
+.. cfgcmd:: set protocols babel parameters diversity-factor <1-256>
+
+  This command sets the multiplicative factor used for diversity routing,
+  in units of 1/256; lower values cause diversity to play a more important role
+  in route selection.
+  The default it 256, which means that diversity plays no role in route
+  selection; you will probably want to set that to 128 or less on nodes
+  with multiple independent radios.
+
+.. cfgcmd:: set protocols babel parameters resend-delay <milliseconds>
+
+  This command specifies the time in milliseconds after which an 'important'
+  request or update will be resent. The default is 2000 ms.
+
+.. cfgcmd:: set protocols babel parameters smoothing-half-life <seconds>
+
+  This command specifies the time constant, in seconds, of the smoothing
+  algorithm used for implementing hysteresis.
+  Larger values reduce route oscillation at the cost of very slightly increasing
+  convergence time. The value 0 disables hysteresis, and is suitable for wired
+  networks. The default is 4 s.
+
+Interfaces Configuration
+------------------------
+
+.. cfgcmd:: set protocols babel interface <interface> type <auto|wired|wireless>
+
+  This command sets the interface type:
+
+  **auto** – automatically determines the interface type.
+  **wired** – enables optimisations for wired interfaces.
+  **wireless** – disables a number of optimisations that are only correct
+  on wired interfaces. Specifying wireless is always correct,
+  but may cause slower convergence and extra routing traffic.
+
+.. cfgcmd:: set protocols babel interface <interface> split-horizon <default|disable|enable>
+
+  This command specifies whether to perform split-horizon on the interface.
+  Specifying no babel split-horizon is always correct, while babel split-horizon
+  is an optimisation that should only be used on symmetric
+  and transitive (wired) networks.
+
+  **default** – enable split-horizon on wired interfaces, and disable
+  split-horizon on wireless interfaces.
+  **enable** – enable split-horizon on this interfaces.
+  **disable** – disable split-horizon on this interfaces.
+
+.. cfgcmd:: set protocols babel interface <interface> hello-interval <milliseconds>
+
+  This command specifies the time in milliseconds between two scheduled hellos.
+  On wired links, Babel notices a link failure within two hello intervals;
+  on wireless links, the link quality value is reestimated at every hello
+  interval.
+  The default is 4000 ms.
+
+.. cfgcmd:: set protocols babel interface <interface> update-interval <milliseconds>
+
+  This command specifies the time in milliseconds between two scheduled updates.
+  Since Babel makes extensive use of triggered updates,
+  this can be set to fairly high values on links with little packet loss.
+  The default is 20000 ms.
+
+.. cfgcmd:: set protocols babel interface <interface> rxcost <1-65534>
+
+  This command specifies the base receive cost for this interface.
+  For wireless interfaces, it specifies the multiplier used for computing
+  the ETX reception cost (default 256);
+  for wired interfaces, it specifies the cost that will be advertised to
+  neighbours.
+
+.. cfgcmd:: set protocols babel interface <interface> rtt-decay <1-256>
+
+  This command specifies the decay factor for the exponential moving average
+  of RTT samples, in units of 1/256.
+  Higher values discard old samples faster. The default is 42.
+
+.. cfgcmd:: set protocols babel interface <interface> rtt-min <milliseconds>
+
+  This command specifies the minimum RTT, in milliseconds,
+  starting from which we increase the cost to a neighbour.
+  The additional cost is linear in (rtt - rtt-min). The default is 10 ms.
+
+.. cfgcmd:: set protocols babel interface <interface> rtt-max <milliseconds>
+
+  This command specifies the maximum RTT, in milliseconds, above which
+  we don't increase the cost to a neighbour. The default is 120 ms.
+
+
+.. cfgcmd:: set protocols babel interface <interface> max-rtt-penalty <milliseconds>
+
+  This command specifies the maximum cost added to a neighbour because of RTT,
+  i.e. when the RTT is higher or equal than rtt-max.
+  The default is 150.
+  Setting it to 0 effectively disables the use of a RTT-based cost.
+
+.. cfgcmd:: set protocols babel interface <interface> enable-timestamps
+
+  This command enables sending timestamps with each Hello and IHU message
+  in order to compute RTT values.
+  It is recommended to enable timestamps on tunnel interfaces.
+
+.. cfgcmd:: set protocols babel interface <interface> channel <1-254|interfering|noninterfering>
+
+  This command set the channel number that diversity routing uses for this
+  interface (see diversity option above).
+
+  **1-254** – interfaces with a channel number interfere with
+  interfering interfaces and interfaces with the same channel number.
+  **interfering** – interfering interfaces are assumed to interfere with all other channels except
+  noninterfering channels.
+  **noninterfering** – noninterfering interfaces are assumed to only interfere
+  with themselves.
+
+Redistribution Configuration
+----------------------------
+
+.. cfgcmd:: set protocols babel redistribute <ipv4|ipv6> <route source>
+
+   This command redistributes routing information from the given route source
+   to the Babel process.
+
+   IPv4 route source: bgp, connected, eigrp, isis, kernel, nhrp, ospf, rip, static.
+
+   IPv6 route source: bgp, connected, eigrp, isis, kernel, nhrp, ospfv3, ripng, static.
+
+.. cfgcmd:: set protocols babel distribute-list <ipv4|ipv6> access-list <in|out> <number>
+
+  This command can be used to filter the Babel routes using access lists.
+  :cfgcmd:`in` and :cfgcmd:`out` this is the direction in which the access
+  lists are applied.
+
+.. cfgcmd:: set protocols babel distribute-list <ipv4|ipv6> interface <interface> access-list <in|out> <number>
+
+  This command allows you apply access lists to a chosen interface to
+  filter the Babel routes.
+
+.. cfgcmd:: set protocols babel distribute-list <ipv4|ipv6> prefix-list <in|out> <name>
+
+  This command can be used to filter the Babel routes using prefix lists.
+  :cfgcmd:`in` and :cfgcmd:`out` this is the direction in which the prefix
+  lists are applied.
+
+.. cfgcmd:: set protocols babel distribute-list <ipv4|ipv6> interface <interface> prefix-list <in|out> <name>
+
+  This command allows you apply prefix lists to a chosen interface to
+  filter the Babel routes.
+
+Configuration Example
+---------------------
+
+Simple Babel configuration using 2 nodes and redistributing connected interfaces.
+
+**Node 1:**
+
+.. code-block:: none
+
+  set interfaces loopback lo address 10.1.1.1/32
+  set interfaces loopback lo address fd12:3456:dead:beef::1/128
+  set protocols babel interface eth0 type wired
+  set protocols babel redistribute ipv4 connected
+  set protocols babel redistribute ipv6 connected
+
+**Node 2:**
+
+.. code-block:: none
+
+  set interfaces loopback lo address 10.2.2.2/32
+  set interfaces loopback lo address fd12:3456:beef:dead::2/128
+  set protocols babel interface eth0 type wired
+  set protocols babel redistribute ipv4 connected
+  set protocols babel redistribute ipv6 connected