.. _babel: .. meta:: :description: The Babel routing protocol provides robust and efficient routing for wired and wireless mesh networks. :keywords: babel, routing, protocol, wireless, mesh, network, metric, ipv4, ipv6 ##### Babel ##### The Babel protocol provides robust and efficient routing for both wired and wireless mesh networks. By default, Babel uses hop-count metrics on wired links and a variant of Expected Transmission Count (ETX) on wireless links. Administrators can configure Babel to account for radio diversity, automatically compute link latency, and include that latency in the routing metric. :rfc:`8966` defines the Babel protocol. Babel is a dual-stack protocol. A single Babel instance routes both IPv4 and IPv6 traffic simultaneously. General configuration --------------------- VyOS does not require a specific command to start the Babel process. The system automatically starts the routing process when you configure the first Babel-enabled interface. .. cfgcmd:: set protocols babel interface **Enable Babel routing on the specified interface.** The system immediately begins sending and receiving Babel packets on this interface. Optional configuration ---------------------- .. cfgcmd:: set protocols babel parameters diversity **Enable radio-frequency diversity routing for the Babel process.** Enabling this feature is highly recommended for networks with many wireless nodes. .. note:: When you enable diversity routing, you should also configure the ``diversity-factor`` and ``channel`` parameters. .. cfgcmd:: set protocols babel parameters diversity-factor <1-256> **Configure the multiplicative factor for diversity routing, in units of 1/256.** Lower multiplicative factors give greater weight to diversity in route selection. The default value is 256, which disables diversity routing. On nodes with multiple independent radios, configure a value of 128 or less. .. cfgcmd:: set protocols babel parameters resend-delay <20-655340> **Configure the delay in milliseconds before the system resends an important request or update.** The default value is 2000 ms. .. cfgcmd:: set protocols babel parameters smoothing-half-life <0-65534> **Configure the time constant, in seconds, for the smoothing algorithm used to implement hysteresis.** Higher values reduce route oscillation but slightly increase convergence time. A value of 0 disables hysteresis and is suitable for wired networks. The default is 4 seconds. Interfaces configuration ------------------------ .. cfgcmd:: set protocols babel interface type **Configure the network type for the Babel-enabled interface.** Choose from the following: * ``auto``: Babel automatically detects if an interface is wired or wireless. * ``wired``: Babel enables optimizations for wired interfaces. * ``wireless``: Babel disables optimizations suitable only for wired interfaces. Specifying wireless is always correct, but may cause slower convergence and increased routing traffic. .. cfgcmd:: set protocols babel interface split-horizon **Configure the split-horizon routing behavior for the specified interface.** Use one of the following options: * ``default``: Babel automatically enables split-horizon on wired interfaces and disables it on wireless interfaces. * ``enable``: Babel enables split-horizon on the interface. This optimization should be used only on symmetric, transitive (wired) networks. * ``disable``: Babel disables split-horizon on the interface. Disabling split-horizon is always safe and correct. .. cfgcmd:: set protocols babel interface hello-interval <20-655340> **Configure the interval, in milliseconds, between scheduled hello messages on the specified interface.** On wired links, Babel detects link failures within two hello intervals. On wireless links, link quality is reestimated at each interval. The default is 4000 ms. .. cfgcmd:: set protocols babel interface update-interval <20-655340> **Configure the interval, in milliseconds, between scheduled routing updates on the specified interface.** Because Babel uses triggered updates extensively, you can increase this value on reliable links with minimal packet loss. The default is 20000 ms. .. cfgcmd:: set protocols babel interface rxcost <1-65534> **Configure the base receive cost for the specified interface.** Babel applies this value based on the configured network type: * ``wired``: The value is the routing cost advertised to neighboring routers. * ``wireless``: The value is a multiplier used to compute the ETX (Expected Transmission Count) reception cost. The default value is 256. .. cfgcmd:: set protocols babel interface rtt-decay <1-256> **Configure the decay factor for the exponential moving average of RTT samples, in units of 1/256.** Higher values discard older samples faster. The default value is 42. .. cfgcmd:: set protocols babel interface rtt-min <1-65535> **Configure the minimum RTT, in milliseconds, at which the cost to a neighbor begins to increase.** The additional cost is linear in (rtt - rtt-min). The default value is 10 ms. .. cfgcmd:: set protocols babel interface rtt-max <1-65535> **Configure the maximum RTT, in milliseconds, above which the cost to a neighbor stops increasing.** The default value is 120 ms. .. cfgcmd:: set protocols babel interface max-rtt-penalty <0-65535> **Configure the maximum cost added to a neighbor when RTT meets or exceeds rtt-max.** Setting this value to 0 disables RTT-based costs. The default value is 150. .. cfgcmd:: set protocols babel interface enable-timestamps **Configure adding timestamps to each Hello and IHU message to calculate RTT values.** Enabling timestamps is recommended for tunnel interfaces. .. cfgcmd:: set protocols babel interface channel <1-254|interfering|noninterfering> **Configure the channel identifier that diversity routing uses for the specified interface.** Interfaces interfere with each other based on the assigned channel identifier: * ``1–254``: The interface interferes with interfaces sharing the same channel number and with interfaces configured as ``interfering``. * ``interfering``: The interface interferes with all others except those configured as ``noninterfering``. * ``noninterfering``: The interface interferes only with itself. Redistribution configuration ---------------------------- .. cfgcmd:: set protocols babel redistribute **Configure the redistribution of routing information from the specified route source into the Babel process.** The following route sources are available: * **ipv4:** ``bgp``, ``connected``, ``eigrp``, ``isis``, ``kernel``, ``nhrp``, ``ospf``, ``rip``, ``static`` * **ipv6:** ``bgp``, ``connected``, ``eigrp``, ``isis``, ``kernel``, ``nhrp``, ``ospfv3``, ``ripng``, ``static`` .. cfgcmd:: set protocols babel distribute-list access-list **Configure global Babel route filtering using an access list.** Specify the direction in which the access list is applied: * ``in``: Filters incoming routes. * ``out``: Filters outgoing routes. .. cfgcmd:: set protocols babel distribute-list interface access-list **Configure Babel route filtering on the specified interface using an access list.** Specify the direction in which the access list is applied: * ``in``: Filters incoming routes. * ``out``: Filters outgoing routes. .. cfgcmd:: set protocols babel distribute-list prefix-list **Configure global Babel route filtering using a prefix list.** Specify the direction in which the prefix list is applied: * ``in``: Filters incoming routes. * ``out``: Filters outgoing routes. .. cfgcmd:: set protocols babel distribute-list interface prefix-list **Configure Babel route filtering on the specified interface using a prefix list.** Specify the direction in which the prefix list is applied: * ``in``: Filters incoming routes. * ``out``: Filters outgoing routes. Configuration example --------------------- Basic two-node babel network ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ **Goal:** The following example connects two routers (Node 1 and Node 2) via their eth0 interfaces and uses the Babel routing protocol to advertise (redistribute) each router's locally configured networks (represented by loopback addresses) to one another. **Node 1:** .. code-block:: none # Configure the loopback (local networks) and physical (eth0) addresses set interfaces loopback lo address 10.1.1.1/32 set interfaces loopback lo address fd12:3456:dead:beef::1/128 set interfaces ethernet eth0 address 192.168.1.1/24 # Enable Babel on the physical link set protocols babel interface eth0 type wired # Instruct Babel to advertise (redistribute) the locally configured networks set protocols babel redistribute ipv4 connected set protocols babel redistribute ipv6 connected **Node 2:** .. code-block:: none # Configure the loopback (local networks) and physical (eth0) addresses set interfaces loopback lo address 10.2.2.2/32 set interfaces loopback lo address fd12:3456:beef:dead::2/128 set interfaces ethernet eth0 address 192.168.1.2/24 # Enable Babel on the physical link set protocols babel interface eth0 type wired # Tell Babel to advertise (redistribute) the locally configured networks set protocols babel redistribute ipv4 connected set protocols babel redistribute ipv6 connected