path: root/docs/interfaces/bond.rst

.. _bond-interface:

####
Bond
####

The bonding interface provides a method for aggregating multiple network
interfaces into a single logical "bonded" interface, or LAG, or ether-channel,
or port-channel. The behavior of the bonded interfaces depends upon the mode;
generally speaking, modes provide either hot standby or load balancing services.
Additionally, link integrity monitoring may be performed.

Configuration
#############

Address
-------

.. cfgcmd:: set interfaces bonding <interface> address <address | dhcp | dhcpv6>

   Configure interface `<interface>` with one or more interface addresses.

   * **address** can be specified multiple times as IPv4 and/or IPv6 address,
     e.g. 192.0.2.1/24 and/or 2001:db8::1/64
   * **dhcp** interface address is received by DHCP from a DHCP server on this
     segment.
   * **dhcpv6** interface address is received by DHCPv6 from a DHCPv6 server on
     this segment.

   Example:

   .. code-block:: none

     set interfaces bonding bond0 address 192.0.2.1/24
     set interfaces bonding bond0 address 192.0.2.2/24
     set interfaces bonding bond0 address 2001:db8::ffff/64
     set interfaces bonding bond0 address 2001:db8:100::ffff/64


.. cfgcmd:: set interfaces bonding <interface> ipv6 address autoconf

   :abbr:`SLAAC (Stateless Address Autoconfiguration)`
   :rfc:`4862`. IPv6 hosts can configure themselves automatically when connected
   to an IPv6 network using the Neighbor Discovery Protocol via :abbr:`ICMPv6
   (Internet Control Message Protocol version 6)` router discovery messages.
   When first connected to a network, a host sends a link-local router
   solicitation multicast request for its configuration parameters; routers
   respond to such a request with a router advertisement packet that contains
   Internet Layer configuration parameters.

   .. note:: This method automatically disables IPv6 traffic forwarding on the
      interface in question.


.. cfgcmd:: set interfaces bonding <interface> ipv6 address eui64 <prefix>

   :abbr:`EUI-64 (64-Bit Extended Unique Identifier)` as specified in
   :rfc:`4291` allows a host to assign iteslf a unique 64-Bit IPv6 address.

   .. code-block:: none

     set interfaces bonding bond0 ipv6 address eui64 2001:db8:beef::/64


Link Administration
-------------------

.. cfgcmd:: set interfaces bonding <interface> description <description>

   Assign given `<description>` to interface. Description will also be passed
   to SNMP monitoring systems.


.. cfgcmd:: set interfaces bonding <interface> disable

   Disable given `<interface>`. It will be placed in administratively down
   (``A/D``) state.

.. cfgcmd:: set interfaces bonding <interface> mac <mac-address>

   Configure user defined :abbr:`MAC (Media Access Control)` address on given
   `<interface>`.

.. cfgcmd:: set interfaces bonding <interface> mode <mode>

   Specifies one of the bonding policies. The default is 802.3ad. Possible
   values are:

   * **802.3ad** - IEEE 802.3ad Dynamic link aggregation. Creates aggregation
     groups that share the same speed and duplex settings. Utilizes all slaves
     in the active aggregator according to the 802.3ad specification.

     Slave selection for outgoing traffic is done according to the transmit
     hash policy, which may be changed from the default simple XOR policy via
     the :cfgcmd:`hash-policy` option, documented below.

     .. note:: Not all transmit policies may be 802.3ad compliant, particularly
        in regards to the packet mis-ordering requirements of section 43.2.4
        of the 802.3ad standard.

   * **active-backup** - Active-backup policy: Only one slave in the bond is
     active. A different slave becomes active if, and only if, the active slave
     fails. The bond's MAC address is externally visible on only one port
     (network adapter) to avoid confusing the switch.

     When a failover occurs in active-backup mode, bonding will issue one or
     more gratuitous ARPs on the newly active slave. One gratuitous ARP is
     issued for the bonding master interface and each VLAN interfaces
     configured above it, provided that the interface has at least one IP
     address configured. Gratuitous ARPs issued for VLAN interfaces are tagged
     with the appropriate VLAN id.

     This mode provides fault tolerance. The :cfgcmd:`primary` option,
     documented below, affects the behavior of this mode.

   * **broadcast** - Broadcast policy: transmits everything on all slave
     interfaces.

     This mode provides fault tolerance.

   * **round-robin** - Round-robin policy: Transmit packets in sequential
     order from the first available slave through the last.

     This mode provides load balancing and fault tolerance.

   * **transmit-load-balance** - Adaptive transmit load balancing: channel
     bonding that does not require any special switch support.

     Incoming traffic is received by the current slave. If the receiving slave
     fails, another slave takes over the MAC address of the failed receiving
     slave.

   * **adaptive-load-balance** - Adaptive load balancing: includes
     transmit-load-balance plus receive load balancing for IPV4 traffic, and
     does not require any special switch support. The receive load balancing
     is achieved by ARP negotiation. The bonding driver intercepts the ARP
     Replies sent by the local system on their way out and overwrites the
     source hardware address with the unique hardware address of one of the
     slaves in the bond such that different peers use different hardware
     addresses for the server.

     Receive traffic from connections created by the server is also balanced.
     When the local system sends an ARP Request the bonding driver copies and
     saves the peer's IP information from the ARP packet. When the ARP Reply
     arrives from the peer, its hardware address is retrieved and the bonding
     driver initiates an ARP reply to this peer assigning it to one of the
     slaves in the bond. A problematic outcome of using ARP negotiation for
     balancing is that each time that an ARP request is broadcast it uses the
     hardware address of the bond. Hence, peers learn the hardware address
     of the bond and the balancing of receive traffic collapses to the current
     slave. This is handled by sending updates (ARP Replies) to all the peers
     with their individually assigned hardware address such that the traffic
     is redistributed. Receive traffic is also redistributed when a new slave
     is added to the bond and when an inactive slave is re-activated. The
     receive load is distributed sequentially (round robin) among the group
     of highest speed slaves in the bond.

     When a link is reconnected or a new slave joins the bond the receive
     traffic is redistributed among all active slaves in the bond by initiating
     ARP Replies with the selected MAC address to each of the clients. The
     updelay parameter (detailed below) must be set to a value equal or greater
     than the switch's forwarding delay so that the ARP Replies sent to the
     peers will not be blocked by the switch.

   * **xor-hash** - XOR policy: Transmit based on the selected transmit
     hash policy.  The default policy is a simple [(source MAC address XOR'd
     with destination MAC address XOR packet type ID) modulo slave count].
     Alternate transmit policies may be selected via the :cfgcmd:`hash-policy`
     option, described below.

     This mode provides load balancing and fault tolerance.

.. cfgcmd:: set interfaces bonding <interface> hash-policy <policy>

   * **layer2** - Uses XOR of hardware MAC addresses and packet type ID field
     to generate the hash. The formula is

     .. code-block:: none

       hash = source MAC XOR destination MAC XOR packet type ID
       slave number = hash modulo slave count

     This algorithm will place all traffic to a particular network peer on
     the same slave.

     This algorithm is 802.3ad compliant.

   * **layer2+3** - This policy uses a combination of layer2 and layer3
     protocol information to generate the hash. Uses XOR of hardware MAC
     addresses and IP addresses to generate the hash. The formula is:

     .. code-block:: none

       hash = source MAC XOR destination MAC XOR packet type ID
       hash = hash XOR source IP XOR destination IP
       hash = hash XOR (hash RSHIFT 16)
       hash = hash XOR (hash RSHIFT 8)

     And then hash is reduced modulo slave count.

     If the protocol is IPv6 then the source and destination addresses are
     first hashed using ipv6_addr_hash.

     This algorithm will place all traffic to a particular network peer on the
     same slave. For non-IP traffic, the formula is the same as for the layer2
     transmit hash policy.

     This policy is intended to provide a more balanced distribution of traffic
     than layer2 alone, especially in environments where a layer3 gateway
     device is required to reach most destinations.

     This algorithm is 802.3ad compliant.

   * **layer3+4** - This policy uses upper layer protocol information, when
     available, to generate the hash. This allows for traffic to a particular
     network peer to span multiple slaves, although a single connection will
     not span multiple slaves.

     The formula for unfragmented TCP and UDP packets is

     .. code-block:: none

       hash = source port, destination port (as in the header)
       hash = hash XOR source IP XOR destination IP
       hash = hash XOR (hash RSHIFT 16)
       hash = hash XOR (hash RSHIFT 8)

     And then hash is reduced modulo slave count.

     If the protocol is IPv6 then the source and destination addresses are
     first hashed using ipv6_addr_hash.

     For fragmented TCP or UDP packets and all other IPv4 and IPv6 protocol
     traffic, the source and destination port information is omitted. For
     non-IP traffic, the formula is the same as for the layer2 transmit hash
     policy.

     This algorithm is not fully 802.3ad compliant. A single TCP or UDP
     conversation containing both fragmented and unfragmented packets will see
     packets striped across two interfaces. This may result in out of order
     delivery. Most traffic types will not meet this criteria, as TCP rarely
     fragments traffic, and most UDP traffic is not involved in extended
     conversations. Other implementations of 802.3ad may or may not tolerate
     this noncompliance.

.. cfgcmd:: set interfaces bonding <interface> primary <interface>

    An `<interface>` specifying which slave is the primary device. The specified
    device will always be the active slave while it is available. Only when the
    primary is off-line will alternate devices be used. This is useful when one
    slave is preferred over another, e.g., when one slave has higher throughput
    than another.

    The primary option is only valid for active-backup, transmit-load-balance,
    and adaptive-load-balance mode.

.. cfgcmd:: set interfaces bonding <interface> arp-monitor interval <time>

   Specifies the ARP link monitoring `<time>` in seconds.

   The ARP monitor works by periodically checking the slave devices to determine
   whether they have sent or received traffic recently (the precise criteria
   depends upon the bonding mode, and the state of the slave). Regular traffic
   is generated via ARP probes issued for the addresses specified by the
   :cfgcmd:`arp-monitor target` option.

   If ARP monitoring is used in an etherchannel compatible mode (modes
   round-robin and xor-hash), the switch should be configured in a mode that
   evenly distributes packets across all links. If the switch is configured to
   distribute the packets in an XOR fashion, all replies from the ARP targets
   will be received on the same link which could cause the other team members
   to fail.

   A value of 0 disables ARP monitoring. The default value is 0.

.. cfgcmd:: set interfaces bonding <interface> arp-monitor target <address>

   Specifies the IP addresses to use as ARP monitoring peers when
   :cfgcmd:`arp-monitor interval` option is > 0. These are the targets of the
   ARP request sent to determine the health of the link to the targets.

   Multiple target IP addresses can be specified. At least one IP address must
   be given for ARP monitoring to function.

   The maximum number of targets that can be specified is 16. The default value
   is no IP addresses.

Member Interfaces
-----------------

.. cfgcmd:: set interfaces bridge <interface> member interface <member>

   Enslave `<member>` interface to bond `<interface>`.

Operation
#########

.. code-block:: none

  vyos@vyos:~$ show interfaces bonding
  Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
  Interface        IP Address                        S/L  Description
  ---------        ----------                        ---  -----------
  bond0            -                                 u/u  my-sw1 int 23 and 24
  bond0.10         192.168.0.1/24                    u/u  office-net
  bond0.100        10.10.10.1/24                     u/u  management-net