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发信人: jjksam (<font color=green><b>Love</b></font>), 信区: Linux
标 题: Linux Bonding Driver mini-howto(转)(转寄)
发信站: 荔园晨风BBS站 (Fri Nov 2 16:44:17 2001), 转信
【 以下文字转载自 jjksam 的信箱 】
【 原文由 jjksam@smth.org 所发表 】
发信人: major (我要6呀我要6呀我要好多6呀), 信区: Linux
标 题: Linux Bonding Driver mini-howto(转)(转寄)
发信站: BBS 水木清华站 (Fri Nov 2 13:56:34 2001)
转载自http://www-miaif.lip6.fr/willy/pub/linux-patches/bonding/bonding.txt
Linux Bonding Driver mini-howto
Initial release : Thomas Davis <tadavis at lbl.gov>
Corrections, HA extensions : 2000/10/03-15 :
- Willy Tarreau <willy at meta-x.org>
- Constantine Gavrilov <const-g at xpert.com>
Note :
------
The bonding driver originally came from Donald Becker's beowulf
patches for
kernel 2.0. It has changed quite a bit since, and the original tools
from
extreme-linux and beowulf sites will not work with this version of the
driver.
For new versions of the driver, patches for older kernels and the
updated
userspace tools, please follow the links at the end of this file.
Installation
============
1) Build kernel with the bonding driver
---------------------------------------
For the latest version of the bonding driver, use kernel 2.2.18 or
above
(otherwise you will need to apply a patch).
Configure kernel with `make menuconfig/xconfig/config', and select
"Bonding driver support" in the "Network device support" section. It
is
recommended to configure the driver as module since it is currently
the only way
to pass parameters to the driver and configure more than one bonding
device.
Build and install the new kernel and modules.
2) Get and install the userspace tools
--------------------------------------
This version of the bonding driver requires updated ifenslave program.
The
original one from extreme-linux and beowulf will not work. Kernels 2.2.
18
and above include the updated version of ifenslave.c in
Documentation/network
directory. For older kernels, please follow the links at the end of this
file.
To install ifenslave.c, do:
# gcc -O2 -s -o ifenslave ifenslave.c
# cp ifenslave /sbin/ifenslave
3) Configure your system
------------------------
Also see the following section on the module parameters. You will need
to add
at least the following line to /etc/conf.modules (or /etc/modules.
conf):
alias bond0 bonding
Use standard distribution techniques to define bond0 network interface.
For
example, on modern RedHat distributions, create ifcfg-bond0 file in
/etc/sysconfig/network-scripts directory that looks like this:
DEVICE=bond0
IPADDR=192.168.1.1
NETMASK=255.255.255.0
NETWORK=192.168.1.0
BROADCAST=192.168.1.255
ONBOOT=yes
BOOTPROTO=none
USERCTL=no
(put the appropriate values for you network instead of 192.168.1).
All interfaces that are part of the trunk, should have SLAVE and
MASTER
definitions. For example, in the case of RedHat, if you wish to make
eth0 and
eth1 (or other interfaces) a part of the bonding interface bond0,
their config
files (ifcfg-eth0, ifcfg-eth1, etc.) should look like this:
DEVICE=eth0
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none
(use DEVICE=eth1 for eth1 and MASTER=bond1 for bond1 if you have
configured
second bonding interface).
Restart the networking subsystem or just bring up the bonding device
if your
administration tools allow it. Otherwise, reboot. (For the case of
RedHat
distros, you can do `ifup bond0' or `/etc/rc.d/init.d/network restart'.
)
If the administration tools of your distribution do not support
master/slave
notation in configuration of network interfaces, you will need to
configure
the bonding device with the following commands manually:
# /sbin/ifconfig bond0 192.168.1.1 up
# /sbin/ifenslave bond0 eth0
# /sbin/ifenslave bond0 eth1
(substitute 192.168.1.1 with your IP address and add custom network
and custom
netmask to the arguments of ifconfig if required).
You can then create a script with these commands and put it into the
appropriate
rc directory.
4) Module parameters.
---------------------
The following module parameters can be passed:
mode=
Possible values are 0 (round robin policy, default) and 1 (active
backup
policy). See HA section for additional info.
miimon=
Use integer value for the frequency (in ms) of MII link monitoring. Zero
value
is default and means the link monitoring will be disabled. A good
value is 100
if you wish to use link monitoring. See HA section for additional info.
downdelay=
Use integer value for delaying disabling a link by this number (in ms)
after
the link failure has been detected. Must be a multiple of miimon.
Default
value is zero. See HA section for additional info.
updelay=
Use integer value for delaying enabling a link by this number (in ms)
after
the "link up" status has been detected. Must be a multiple of miimon.
Default
value is zero. See HA section for additional info.
If you need to configure several bonding devices, the driver must be
loaded
several times. I.e. for two bonding devices, your /etc/conf.modules must
look
like this:
alias bond0 bonding
alias bond1 bonding
options bond0 miimon=100
options bond1 -o bonding1 miimon=100
5) Testing configuration
------------------------
You can test the configuration and transmit policy with ifconfig. For
example,
for round robin policy, you should get something like this:
[root]# /sbin/ifconfig
bond0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.
255.252.0
UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
RX packets:7224794 errors:0 dropped:0 overruns:0 frame:0
TX packets:3286647 errors:1 dropped:0 overruns:1 carrier:0
collisions:0 txqueuelen:0
eth0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.
255.252.0
UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
RX packets:3573025 errors:0 dropped:0 overruns:0 frame:0
TX packets:1643167 errors:1 dropped:0 overruns:1 carrier:0
collisions:0 txqueuelen:100
Interrupt:10 Base address:0x1080
eth1 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.
255.252.0
UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
RX packets:3651769 errors:0 dropped:0 overruns:0 frame:0
TX packets:1643480 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
Interrupt:9 Base address:0x1400
Questions :
===========
1. Is it SMP safe?
Yes. The old 2.0.xx channel bonding patch was not SMP safe.
The new driver was designed to be SMP safe from the start.
2. What type of cards will work with it?
Any Ethernet type cards (you can even mix cards - a Intel
EtherExpress PRO/100 and a 3com 3c905b, for example).
You can even bond together Gigabit Ethernet cards!
3. How many bonding devices can I have?
One for each module you load. See section on module parameters for
how
to accomplish this.
4. How many slaves can a bonding device have?
Limited by the number of network interfaces Linux supports and the
number of cards you can place in your system.
5. What happens when a slave link dies?
If your ethernet cards support MII status monitoring and the MII
monitoring has been enabled in the driver (see description of module
parameters), there will be no adverse consequences. This release
of the bonding driver knows how to get the MII information and
enables or disables its slaves according to their link status.
See section on HA for additional information.
All ethernet drivers which cannot report their link state will not
handle this situation very well. The bonding driver will continue
to send packets but some packets will be lost. Retransmits will
cause serious degradation of performance (in the case when one
of two slave links fails, 50% packets will be lost, which is a
serious
problem for both TCP and UDP).
6. Can bonding be used for High Availability?
Yes, if you use MII monitoring and ALL your cards support MII link
status reporting. See section on HA for more information.
7. Which switches/systems does it work with?
In round-robin mode, it works with systems that support trunking:
* Cisco 5500 series (look for EtherChannel support).
* SunTrunking software.
* Alteon AceDirector switches / WebOS (use Trunks).
* BayStack Switches (trunks must be explicitly configured). Stackable
models (450) can define trunks between ports on different physical
units.
* Linux bonding, of course !
In Active-backup mode, it should work with any Layer-II switches.
8. Where does a bonding device get its MAC address from?
If not explicitly configured with ifconfig, the MAC address of the
bonding device is taken from its first slave device. This MAC address
is then passed to all following slaves and remains persistent (even
if
the the first slave is removed) until the bonding device is brought
down or reconfigured.
If you wish to change the MAC address, you can set it with ifconfig:
# ifconfig bond0 ha ether 00:11:22:33:44:55
The MAC address can be also changed by bringing down/up the device
and then changing its slaves (or their order):
# ifconfig bond0 down ; modprobe -r bonding
# ifconfig bond0 .... up
# ifenslave bond0 eth...
This method will automatically take the address from the next slave
that will be added.
To restore your slaves' MAC addresses, you need to detach them
from the bond (`ifenslave -d bond0 eth0'), set them down
(`ifconfig eth0 down'), unload the drivers (`rmmod 3c59x', for
example) and reload them to get the MAC addresses from their
eeproms. If the driver is shared by several devices, you need
to turn them all down. Another solution is to look for the MAC
address at boot time (dmesg or tail /var/log/messages) and to
reset it by hand with ifconfig :
# ifconfig eth0 down
# ifconfig eth0 hw ether 00:20:40:60:80:A0
9. Which transmit polices can be used?
Round robin, based on the order of enslaving, and active-backup
policy
that ensures that one and only one device will transmit at any given
moment, can be used. Active-backup policy is useful for implementing
high availability solutions using two switches (see section on HA).
High availability
=================
To implement high availability using the bonding driver, you need to
compile the driver as module because currently it is the only way to
pass
parameters to the driver. This may change in the future.
High availability is achieved by using MII status reporting. You need
to
verify that all your interfaces support MII link status reporting. On
Linux
kernel 2.2.17, all the 100 Mbps capable drivers and yellowfin gigabit
driver
support it. If your system has an interface that does not support MII
status
reporting, a failure of its link will not be detected!
The bonding driver can regularly check all its slaves links by
checking the
MII status registers. The check interval is specified by the module
argument
"miimon" (MII monitoring). It takes an integer that represents the
checking time in milliseconds. It should not come to close to
(1000/HZ)
(10 ms on i386) because it may then reduce the system interactivity. 100
ms
seems to be a good value. It means that a dead link will be detected
at most
100 ms after it goes down.
Example:
# modprobe bonding miimon=100
Or, put in your /etc/modules.conf :
alias bond0 bonding
options bond0 miimon=100
There are currently two policies for high availability, depending on
whether
a) hosts are connected to a single host or switch that support
trunking
b) hosts are connected to several different switches or a single
switch that
does not support trunking.
1) HA on a single switch or host - load balancing
-------------------------------------------------
It is the easiest to set up and to understand. Simply configure the
remote equipment (host or switch) to aggregate traffic over several
ports (trunk, etherchannel, etc.) and configure the bonding interfaces.
If the module has been loaded with the proper MII option, it will work
automatically. You can then try to remove and restore different links
and see in your logs what the driver detects. When testing, you may
encounter problems on some buggy switches that disable the trunk for a
long time if all ports in a trunk go down. This is not Linux, but
really
the switch (reboot it to ensure).
Example 1 : host to host at double speed
+----------+ +----------+
| |eth0 eth0| |
| Host A +--------------------------+ Host B |
| +--------------------------+ |
| |eth1 eth1| |
+----------+ +----------+
On each host :
# modprobe bonding miimon=100
# ifconfig bond0 addr
# ifenslave bond0 eth0 eth1
Example 2 : host to switch at double speed
+----------+ +----------+
| |eth0 port1| |
| Host A +--------------------------+ switch |
| +--------------------------+ |
| |eth1 port2| |
+----------+ +----------+
On host A : On the switch :
# modprobe bonding miimon=100 # set up a trunk on port1
# ifconfig bond0 addr and port2
# ifenslave bond0 eth0 eth1
2) HA on two or more switches (or a single switch without trunking
support)
------------------------------------------------------------------------
---
This mode is more problematic because it relies on the fact that there
are multiple ports and the host's MAC address should be visible on one
port only to avoid confusing the switches.
If you need to know which interface is the active one, and which ones
are
backup, use ifconfig. All backup interfaces have the NOARP flag set.
To use this mode, pass "mode=1" to the module at load time :
# modprobe bonding miimon=100 mode=1
Or, put in your /etc/modules.conf :
alias bond0 bonding
options bond0 miimon=100 mode=1
Example 1: Using multiple host and multiple switches to build a "no
single
point of failure" solution.
| |
|port3 port3|
+-----+----+ +-----+----+
| |port7 ISL port7| |
| switch A +--------------------------+ switch B |
| +--------------------------+ |
| |port8 port8| |
+----++----+ +-----++---+
port2||port1 port1||port2
|| +-------+ ||
|+-------------+ host1 +---------------+|
| eth0 +-------+ eth1 |
| |
| +-------+ |
+--------------+ host2 +----------------+
eth0 +-------+ eth1
In this configuration, there are an ISL - Inter Switch Link (could be
a trunk),
several servers (host1, host2 ...) attached to both switches each, and
one or
more ports to the outside world (port3...). One an only one slave on
each host
is active at a time, while all links are still monitored (the system
can
detect a failure of active and backup links).
Each time a host changes its active interface, it sticks to the new
one until
it goes down. In this example, the hosts are not too much affected by
the
expiration time of the switches' forwarding tables.
If host1 and host2 have the same functionality and are used in load
balancing
by another external mechanism, it is good to have host1's active
interface
connected to one switch and host2's to the other. Such system will
survive
a failure of a single host, cable, or switch. The worst thing that may
happen
in the case of a switch failure is that half of the hosts will be
temporarily
unreachable until the other switch expires its tables.
Example 2: Using multiple ethernet cards connected to a switch to
configure
NIC failover (switch is not required to support trunking).
+----------+ +----------+
| |eth0 port1| |
| Host A +--------------------------+ switch |
| +--------------------------+ |
| |eth1 port2| |
+----------+ +----------+
On host A : On the switch :
# modprobe bonding miimon=100 mode=1 # (optional) minimize
the time
# ifconfig bond0 addr # for table expiration
# ifenslave bond0 eth0 eth1
Each time the host changes its active interface, it sticks to the new
one until
it goes down. In this example, the host is strongly affected by the
expiration
time of the switch forwarding table.
3) Adapting to your switches' timing
------------------------------------
If your switches take a long time to go into backup mode, it may be
desirable not to activate a backup interface immediately after a link
goes
down. It is possible to delay the moment at which a link will be
completely disabled by passing the module parameter "downdelay" (in
milliseconds, must be a multiple of miimon).
When a switch reboots, it is possible that its ports report "link up"
status
before they become usable. This could fool a bond device by causing it
to
use some ports that are not ready yet. It is possible to delay the
moment at
which an active link will be reused by passing the module parameter
"updelay"
(in milliseconds, must be a multiple of miimon).
A similar situation can occur when a host re-negotiates a lost link with
the
switch (a case of cable replacement).
A special case is when a bonding interface has lost all slave links.
Then the
driver will immediately reuse the first link that goes up, even if
updelay
parameter was specified. (If there are slave interfaces in the "updelay"
state,
the interface that first went into that state will be immediately
reused.) This
allows to reduce down-time if the value of updelay has been
overestimated.
Examples :
# modprobe bonding miimon=100 mode=1 downdelay=2000 updelay=5000
# modprobe bonding miimon=100 mode=0 downdelay=0 updelay=5000
4) Limitations
--------------
The main limitations are :
- only the link status is monitored. If the switch on the other side
is
partially down (e.g. doesn't forward anymore, but the link is OK),
the link
won't be disabled. Another way to check for a dead link could be
to count
incoming frames on a heavily loaded host. This is not applicable
to small
servers, but may be useful when the front switches send multicast
information on their links (e.g. VRRP), or even health-check the
servers.
This is currently being worked on. Until this is implemented, it
is better
to distribute active hosts across several switches.
- must be ported to Linux Kernel 2.4
Resources and links
===================
Donald Becker's Ethernet Drivers and diag programs may be found at :
- http://www.scyld.com/network/
- http://cesdis.gsfc.nasa.gov/linux/drivers/ (seems to be dead
now)
- ftp://cesdis.gsfc.nasa.goc/pub/linux/drivers/ (seems to be dead
now)
You will also find a lot of information regarding Ethernet, NWay, MII,
etc. at
www.scyld.com.
For new versions of the driver, patches for older kernels and the
updated
userspace tools, take a look at Willy Tarreau's site :
- http://wtarreau.free.fr/pub/bonding/
- http://www-miaif.lip6.fr/willy/pub/bonding/
To get latest informations about Linux Kernel development, please
consult
the Linux Kernel Mailing List Archives at :
http://boudicca.tux.org/hypermail/linux-kernel/latest/
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