Linux Ethernet Bonding Driver HOWTO
- Latest update: 21 June 2005
+ Latest update: 24 April 2006
Initial release : Thomas Davis <tadavis at lbl.gov>
Corrections, HA extensions : 2000/10/03-15 :
- Jay Vosburgh <fubar at us dot ibm dot com>
Reorganized and updated Feb 2005 by Jay Vosburgh
+Added Sysfs information: 2006/04/24
+ - Mitch Williams <mitch.a.williams at intel.com>
Introduction
============
2. Bonding Driver Options
3. Configuring Bonding Devices
-3.1 Configuration with sysconfig support
-3.1.1 Using DHCP with sysconfig
-3.1.2 Configuring Multiple Bonds with sysconfig
-3.2 Configuration with initscripts support
-3.2.1 Using DHCP with initscripts
-3.2.2 Configuring Multiple Bonds with initscripts
-3.3 Configuring Bonding Manually
+3.1 Configuration with Sysconfig Support
+3.1.1 Using DHCP with Sysconfig
+3.1.2 Configuring Multiple Bonds with Sysconfig
+3.2 Configuration with Initscripts Support
+3.2.1 Using DHCP with Initscripts
+3.2.2 Configuring Multiple Bonds with Initscripts
+3.3 Configuring Bonding Manually with Ifenslave
3.3.1 Configuring Multiple Bonds Manually
+3.4 Configuring Bonding Manually via Sysfs
-5. Querying Bonding Configuration
-5.1 Bonding Configuration
-5.2 Network Configuration
+4. Querying Bonding Configuration
+4.1 Bonding Configuration
+4.2 Network Configuration
-6. Switch Configuration
+5. Switch Configuration
-7. 802.1q VLAN Support
+6. 802.1q VLAN Support
-8. Link Monitoring
-8.1 ARP Monitor Operation
-8.2 Configuring Multiple ARP Targets
-8.3 MII Monitor Operation
+7. Link Monitoring
+7.1 ARP Monitor Operation
+7.2 Configuring Multiple ARP Targets
+7.3 MII Monitor Operation
-9. Potential Trouble Sources
-9.1 Adventures in Routing
-9.2 Ethernet Device Renaming
-9.3 Painfully Slow Or No Failed Link Detection By Miimon
+8. Potential Trouble Sources
+8.1 Adventures in Routing
+8.2 Ethernet Device Renaming
+8.3 Painfully Slow Or No Failed Link Detection By Miimon
-10. SNMP agents
+9. SNMP agents
-11. Promiscuous mode
+10. Promiscuous mode
-12. Configuring Bonding for High Availability
-12.1 High Availability in a Single Switch Topology
-12.2 High Availability in a Multiple Switch Topology
-12.2.1 HA Bonding Mode Selection for Multiple Switch Topology
-12.2.2 HA Link Monitoring for Multiple Switch Topology
+11. Configuring Bonding for High Availability
+11.1 High Availability in a Single Switch Topology
+11.2 High Availability in a Multiple Switch Topology
+11.2.1 HA Bonding Mode Selection for Multiple Switch Topology
+11.2.2 HA Link Monitoring for Multiple Switch Topology
-13. Configuring Bonding for Maximum Throughput
-13.1 Maximum Throughput in a Single Switch Topology
-13.1.1 MT Bonding Mode Selection for Single Switch Topology
-13.1.2 MT Link Monitoring for Single Switch Topology
-13.2 Maximum Throughput in a Multiple Switch Topology
-13.2.1 MT Bonding Mode Selection for Multiple Switch Topology
-13.2.2 MT Link Monitoring for Multiple Switch Topology
+12. Configuring Bonding for Maximum Throughput
+12.1 Maximum Throughput in a Single Switch Topology
+12.1.1 MT Bonding Mode Selection for Single Switch Topology
+12.1.2 MT Link Monitoring for Single Switch Topology
+12.2 Maximum Throughput in a Multiple Switch Topology
+12.2.1 MT Bonding Mode Selection for Multiple Switch Topology
+12.2.2 MT Link Monitoring for Multiple Switch Topology
-14. Switch Behavior Issues
-14.1 Link Establishment and Failover Delays
-14.2 Duplicated Incoming Packets
+13. Switch Behavior Issues
+13.1 Link Establishment and Failover Delays
+13.2 Duplicated Incoming Packets
-15. Hardware Specific Considerations
-15.1 IBM BladeCenter
+14. Hardware Specific Considerations
+14.1 IBM BladeCenter
-16. Frequently Asked Questions
+15. Frequently Asked Questions
-17. Resources and Links
+16. Resources and Links
1. Bonding Driver Installation
onwards) do not have /usr/include/linux symbolically linked to the
default kernel source include directory.
+SECOND IMPORTANT NOTE:
+ If you plan to configure bonding using sysfs, you do not need
+to use ifenslave.
2. Bonding Driver Options
=========================
In bonding version 2.6.2 or later, when a failover
occurs in active-backup mode, bonding will issue one
or more gratuitous ARPs on the newly active slave.
- One gratutious ARP is issued for the bonding master
+ 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
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
+ 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
3. Configuring Bonding Devices
==============================
- There are, essentially, two methods for configuring bonding:
-with support from the distro's network initialization scripts, and
-without. Distros generally use one of two packages for the network
-initialization scripts: initscripts or sysconfig. Recent versions of
-these packages have support for bonding, while older versions do not.
+ You can configure bonding using either your distro's network
+initialization scripts, or manually using either ifenslave or the
+sysfs interface. Distros generally use one of two packages for the
+network initialization scripts: initscripts or sysconfig. Recent
+versions of these packages have support for bonding, while older
+versions do not.
We will first describe the options for configuring bonding for
distros using versions of initscripts and sysconfig with full or
If this returns any matches, then your initscripts or
sysconfig has support for bonding.
-3.1 Configuration with sysconfig support
+3.1 Configuration with Sysconfig Support
----------------------------------------
This section applies to distros using a version of sysconfig
SuSE SLES 9's networking configuration system does support
bonding, however, at this writing, the YaST system configuration
-frontend does not provide any means to work with bonding devices.
+front end does not provide any means to work with bonding devices.
Bonding devices can be managed by hand, however, as follows.
First, if they have not already been configured, configure the
Note that the template does not document the various BONDING_
settings described above, but does describe many of the other options.
-3.1.1 Using DHCP with sysconfig
+3.1.1 Using DHCP with Sysconfig
-------------------------------
Under sysconfig, configuring a device with BOOTPROTO='dhcp'
the slave devices. Without active slaves, the DHCP requests are not
sent to the network.
-3.1.2 Configuring Multiple Bonds with sysconfig
+3.1.2 Configuring Multiple Bonds with Sysconfig
-----------------------------------------------
The sysconfig network initialization system is capable of
options in the ifcfg-bondX file, it is not necessary to add them to
the system /etc/modules.conf or /etc/modprobe.conf configuration file.
-3.2 Configuration with initscripts support
+3.2 Configuration with Initscripts Support
------------------------------------------
This section applies to distros using a version of initscripts
will restart the networking subsystem and your bond link should be now
up and running.
-3.2.1 Using DHCP with initscripts
+3.2.1 Using DHCP with Initscripts
---------------------------------
Recent versions of initscripts (the version supplied with
and add a line consisting of "TYPE=Bonding". Note that the TYPE value
is case sensitive.
-3.2.2 Configuring Multiple Bonds with initscripts
+3.2.2 Configuring Multiple Bonds with Initscripts
-------------------------------------------------
At this writing, the initscripts package does not directly
exhibiting this problem, it will be impossible to configure multiple
bonds with differing parameters.
-3.3 Configuring Bonding Manually
---------------------------------
+3.3 Configuring Bonding Manually with Ifenslave
+-----------------------------------------------
This section applies to distros whose network initialization
scripts (the sysconfig or initscripts package) do not have specific
This may be repeated any number of times, specifying a new and
unique name in place of bond1 for each subsequent instance.
+3.4 Configuring Bonding Manually via Sysfs
+------------------------------------------
+
+ Starting with version 3.0, Channel Bonding may be configured
+via the sysfs interface. This interface allows dynamic configuration
+of all bonds in the system without unloading the module. It also
+allows for adding and removing bonds at runtime. Ifenslave is no
+longer required, though it is still supported.
+
+ Use of the sysfs interface allows you to use multiple bonds
+with different configurations without having to reload the module.
+It also allows you to use multiple, differently configured bonds when
+bonding is compiled into the kernel.
+
+ You must have the sysfs filesystem mounted to configure
+bonding this way. The examples in this document assume that you
+are using the standard mount point for sysfs, e.g. /sys. If your
+sysfs filesystem is mounted elsewhere, you will need to adjust the
+example paths accordingly.
+
+Creating and Destroying Bonds
+-----------------------------
+To add a new bond foo:
+# echo +foo > /sys/class/net/bonding_masters
+
+To remove an existing bond bar:
+# echo -bar > /sys/class/net/bonding_masters
+
+To show all existing bonds:
+# cat /sys/class/net/bonding_masters
+
+NOTE: due to 4K size limitation of sysfs files, this list may be
+truncated if you have more than a few hundred bonds. This is unlikely
+to occur under normal operating conditions.
+
+Adding and Removing Slaves
+--------------------------
+ Interfaces may be enslaved to a bond using the file
+/sys/class/net/<bond>/bonding/slaves. The semantics for this file
+are the same as for the bonding_masters file.
+
+To enslave interface eth0 to bond bond0:
+# ifconfig bond0 up
+# echo +eth0 > /sys/class/net/bond0/bonding/slaves
+
+To free slave eth0 from bond bond0:
+# echo -eth0 > /sys/class/net/bond0/bonding/slaves
+
+ NOTE: The bond must be up before slaves can be added. All
+slaves are freed when the interface is brought down.
+
+ When an interface is enslaved to a bond, symlinks between the
+two are created in the sysfs filesystem. In this case, you would get
+/sys/class/net/bond0/slave_eth0 pointing to /sys/class/net/eth0, and
+/sys/class/net/eth0/master pointing to /sys/class/net/bond0.
+
+ This means that you can tell quickly whether or not an
+interface is enslaved by looking for the master symlink. Thus:
+# echo -eth0 > /sys/class/net/eth0/master/bonding/slaves
+will free eth0 from whatever bond it is enslaved to, regardless of
+the name of the bond interface.
+
+Changing a Bond's Configuration
+-------------------------------
+ Each bond may be configured individually by manipulating the
+files located in /sys/class/net/<bond name>/bonding
+
+ The names of these files correspond directly with the command-
+line parameters described elsewhere in in this file, and, with the
+exception of arp_ip_target, they accept the same values. To see the
+current setting, simply cat the appropriate file.
+
+ A few examples will be given here; for specific usage
+guidelines for each parameter, see the appropriate section in this
+document.
+
+To configure bond0 for balance-alb mode:
+# ifconfig bond0 down
+# echo 6 > /sys/class/net/bond0/bonding/mode
+ - or -
+# echo balance-alb > /sys/class/net/bond0/bonding/mode
+ NOTE: The bond interface must be down before the mode can be
+changed.
+
+To enable MII monitoring on bond0 with a 1 second interval:
+# echo 1000 > /sys/class/net/bond0/bonding/miimon
+ NOTE: If ARP monitoring is enabled, it will disabled when MII
+monitoring is enabled, and vice-versa.
+
+To add ARP targets:
+# echo +192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target
+# echo +192.168.0.101 > /sys/class/net/bond0/bonding/arp_ip_target
+ NOTE: up to 10 target addresses may be specified.
+
+To remove an ARP target:
+# echo -192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target
+
+Example Configuration
+---------------------
+ We begin with the same example that is shown in section 3.3,
+executed with sysfs, and without using ifenslave.
+
+ To make a simple bond of two e100 devices (presumed to be eth0
+and eth1), and have it persist across reboots, edit the appropriate
+file (/etc/init.d/boot.local or /etc/rc.d/rc.local), and add the
+following:
+
+modprobe bonding
+modprobe e100
+echo balance-alb > /sys/class/net/bond0/bonding/mode
+ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up
+echo 100 > /sys/class/net/bond0/bonding/miimon
+echo +eth0 > /sys/class/net/bond0/bonding/slaves
+echo +eth1 > /sys/class/net/bond0/bonding/slaves
+
+ To add a second bond, with two e1000 interfaces in
+active-backup mode, using ARP monitoring, add the following lines to
+your init script:
+
+modprobe e1000
+echo +bond1 > /sys/class/net/bonding_masters
+echo active-backup > /sys/class/net/bond1/bonding/mode
+ifconfig bond1 192.168.2.1 netmask 255.255.255.0 up
+echo +192.168.2.100 /sys/class/net/bond1/bonding/arp_ip_target
+echo 2000 > /sys/class/net/bond1/bonding/arp_interval
+echo +eth2 > /sys/class/net/bond1/bonding/slaves
+echo +eth3 > /sys/class/net/bond1/bonding/slaves
+
-5. Querying Bonding Configuration
+4. Querying Bonding Configuration
=================================
-5.1 Bonding Configuration
+4.1 Bonding Configuration
-------------------------
Each bonding device has a read-only file residing in the
The precise format and contents will change depending upon the
bonding configuration, state, and version of the bonding driver.
-5.2 Network configuration
+4.2 Network configuration
-------------------------
The network configuration can be inspected using the ifconfig
collisions:0 txqueuelen:100
Interrupt:9 Base address:0x1400
-6. Switch Configuration
+5. Switch Configuration
=======================
For this section, "switch" refers to whatever system the
with another EtherChannel group.
-7. 802.1q VLAN Support
+6. 802.1q VLAN Support
======================
It is possible to configure VLAN devices over a bond interface
mode, which might not be what you want.
-8. Link Monitoring
+7. Link Monitoring
==================
The bonding driver at present supports two schemes for
bonding driver itself, it is not possible to enable both ARP and MII
monitoring simultaneously.
-8.1 ARP Monitor Operation
+7.1 ARP Monitor Operation
-------------------------
The ARP monitor operates as its name suggests: it sends ARP
shows the ARP requests and replies on the network, then it may be that
your device driver is not updating last_rx and trans_start.
-8.2 Configuring Multiple ARP Targets
+7.2 Configuring Multiple ARP Targets
------------------------------------
While ARP monitoring can be done with just one target, it can
options bond0 arp_interval=60 arp_ip_target=192.168.0.100
-8.3 MII Monitor Operation
+7.3 MII Monitor Operation
-------------------------
The MII monitor monitors only the carrier state of the local
and ethtool requests), then the MII monitor will assume the link is
up.
-9. Potential Sources of Trouble
+8. Potential Sources of Trouble
===============================
-9.1 Adventures in Routing
+8.1 Adventures in Routing
-------------------------
When bonding is configured, it is important that the slave
-devices not have routes that supercede routes of the master (or,
+devices not have routes that supersede routes of the master (or,
generally, not have routes at all). For example, suppose the bonding
device bond0 has two slaves, eth0 and eth1, and the routing table is
as follows:
The solution here is simply to insure that slaves do not have
routes of their own, and if for some reason they must, those routes do
-not supercede routes of their master. This should generally be the
+not supersede routes of their master. This should generally be the
case, but unusual configurations or errant manual or automatic static
route additions may cause trouble.
-9.2 Ethernet Device Renaming
+8.2 Ethernet Device Renaming
----------------------------
On systems with network configuration scripts that do not
place. Full documentation on this can be found in the modprobe.conf
and modprobe manual pages.
-9.3. Painfully Slow Or No Failed Link Detection By Miimon
+8.3. Painfully Slow Or No Failed Link Detection By Miimon
---------------------------------------------------------
By default, bonding enables the use_carrier option, which
beyond other ports of a switch, or if a switch is refusing to pass
traffic while still maintaining carrier on.
-10. SNMP agents
+9. SNMP agents
===============
If running SNMP agents, the bonding driver should be loaded
and SNMP functions such as Interface_Scan_Next will report that
association.
-11. Promiscuous mode
+10. Promiscuous mode
====================
When running network monitoring tools, e.g., tcpdump, it is
the active slave changes (e.g., due to a link failure), the
promiscuous setting will be propagated to the new active slave.
-12. Configuring Bonding for High Availability
+11. Configuring Bonding for High Availability
=============================================
High Availability refers to configurations that provide
(i.e., the network always works), even though other configurations
could provide higher throughput.
-12.1 High Availability in a Single Switch Topology
+11.1 High Availability in a Single Switch Topology
--------------------------------------------------
If two hosts (or a host and a single switch) are directly
See Section 13, "Configuring Bonding for Maximum Throughput"
for information on configuring bonding with one peer device.
-12.2 High Availability in a Multiple Switch Topology
+11.2 High Availability in a Multiple Switch Topology
----------------------------------------------------
With multiple switches, the configuration of bonding and the
the outside world ("port3" on each switch). There is no technical
reason that this could not be extended to a third switch.
-12.2.1 HA Bonding Mode Selection for Multiple Switch Topology
+11.2.1 HA Bonding Mode Selection for Multiple Switch Topology
-------------------------------------------------------------
In a topology such as the example above, the active-backup and
necessary for some specific one-way traffic to reach both
independent networks, then the broadcast mode may be suitable.
-12.2.2 HA Link Monitoring Selection for Multiple Switch Topology
+11.2.2 HA Link Monitoring Selection for Multiple Switch Topology
----------------------------------------------------------------
The choice of link monitoring ultimately depends upon your
target to query.
-13. Configuring Bonding for Maximum Throughput
+12. Configuring Bonding for Maximum Throughput
==============================================
-13.1 Maximizing Throughput in a Single Switch Topology
+12.1 Maximizing Throughput in a Single Switch Topology
------------------------------------------------------
In a single switch configuration, the best method to maximize
mode is described below.
-13.1.1 MT Bonding Mode Selection for Single Switch Topology
+12.1.1 MT Bonding Mode Selection for Single Switch Topology
-----------------------------------------------------------
This configuration is the easiest to set up and to understand,
device driver must support changing the hardware address while
the device is open.
-13.1.2 MT Link Monitoring for Single Switch Topology
+12.1.2 MT Link Monitoring for Single Switch Topology
----------------------------------------------------
The choice of link monitoring may largely depend upon which
the MII monitor (which does not provide as high a level of end to end
assurance as the ARP monitor).
-13.2 Maximum Throughput in a Multiple Switch Topology
+12.2 Maximum Throughput in a Multiple Switch Topology
-----------------------------------------------------
Multiple switches may be utilized to optimize for throughput
can be equipped with an additional network device connected to an
external network; this host then additionally acts as a gateway.
-13.2.1 MT Bonding Mode Selection for Multiple Switch Topology
+12.2.1 MT Bonding Mode Selection for Multiple Switch Topology
-------------------------------------------------------------
In actual practice, the bonding mode typically employed in
mode allows individual connections between two hosts to effectively
utilize greater than one interface's bandwidth.
-13.2.2 MT Link Monitoring for Multiple Switch Topology
+12.2.2 MT Link Monitoring for Multiple Switch Topology
------------------------------------------------------
Again, in actual practice, the MII monitor is most often used
needed as the number of systems involved grows (remember that each
host in the network is configured with bonding).
-14. Switch Behavior Issues
+13. Switch Behavior Issues
==========================
-14.1 Link Establishment and Failover Delays
+13.1 Link Establishment and Failover Delays
-------------------------------------------
Some switches exhibit undesirable behavior with regard to the
to not activate a backup interface immediately after a link goes down.
Failover may be delayed via the downdelay bonding module option.
-14.2 Duplicated Incoming Packets
+13.2 Duplicated Incoming Packets
--------------------------------
It is not uncommon to observe a short burst of duplicated
most Cisco switches, the privileged command "clear mac address-table
dynamic" will accomplish this).
-15. Hardware Specific Considerations
+14. Hardware Specific Considerations
====================================
This section contains additional information for configuring
bonding on specific hardware platforms, or for interfacing bonding
with particular switches or other devices.
-15.1 IBM BladeCenter
+14.1 IBM BladeCenter
--------------------
This applies to the JS20 and similar systems.
avoid fail-over delay issues when using bonding.
-16. Frequently Asked Questions
+15. Frequently Asked Questions
==============================
1. Is it SMP safe?
support specific features (described in the appropriate section under
module parameters, above).
- In 802.3ad mode, it works with with systems that support IEEE
+ In 802.3ad mode, it works with systems that support IEEE
802.3ad Dynamic Link Aggregation. Most managed and many unmanaged
switches currently available support 802.3ad.
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