lagg支持IEEE802.3ad链路聚合控制协议(LACP)和标记协议。LACP能够在节点与若干链路聚合组之间协商链路。每一个链路聚合组(LAG)由一组相同速度、以全双工模式运行的网口组成。流量在LAG中的网口之间，会以总速度最大的原则进行分摊。当物理链路发生变化时，链路聚合会迅速适应变动形成新的配置。

一、调入lagg内核模块

方法1.加入内核并重编和加载,我用此方法来实现

devicelagg

方法2.以module调入(kldload),注意调入前先确认lagg.ko模块存在于/boot/kernel/

if_lagg_load="YES"

二、在rc.conf下配置lagg。

假设网卡标识为bge0和bge1

ifconfig_bge0="up"

ifconfig_bge1="up"

cloned_interfaces="lagg0"

ifconfig_lagg0="laggprotolacplaggportbge0laggportbge1192.168.10.21netmask255.255.255.0"

三、cisco2950下配置channel-protocol和channel-group.

#showrun的有关channel-protocol的内容

interfaceFastEthernet0/23

channel-group6modeactive

channel-protocollacp

!

interfaceFastEthernet0/24

channel-group6modeactive

channel-protocollacp

!

具体配置:

#enable

#conft

#intfa0/24

#channel-protocollacp

#channel-group6modeactive

#exit

#intfa0/23

#channel-protocollacp

#channel-group6modeactive

#exit

#exit

#write

四、重启pc,这样就可以实现FreeBSD的两个网口作为一个负载均衡和故障转移链路聚合组接到交换机上。

A.FreeBSD上的状态.

#ifconfig

root@s2[~]#ifconfig

bge0:flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST>metric0mtu1500

options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>

ether00:0f:20:32:5a:af

media:Ethernetautoselect(100baseTX<full-duplex>)

status:active

lagg:laggdevlagg0

bge1:flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST>metric0mtu1500

options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>

ether00:0f:20:32:5a:af

media:Ethernetautoselect(100baseTX<full-duplex>)

status:active

lagg:laggdevlagg0

lo0:flags=8049<UP,LOOPBACK,RUNNING,MULTICAST>metric0mtu16384

inet127.0.0.1netmask0xff000000

lagg0:flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST>metric0mtu1500

options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>

ether00:0f:20:32:5a:af

inet192.168.10.21netmask0xffffff00broadcast192.168.10.255

media:Ethernetautoselect

status:active

laggprotolacp

laggport:bge1flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>

laggport:bge0flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>

B.在交换机上的状态.

swicth#showlacp6neighbor

Flags:S-DeviceisrequestingSlowLACPDUs

F-DeviceisrequestingFastLACPDUs

A-DeviceisinActivemodeP-DeviceisinPassivemode

Channelgroup6neighbors

Partner'sinformation:

LACPportOperPortPort

PortFlagsPriorityDevIDAgeKeyNumberState

Fa0/23SA32768000f.2032.5aaf3s0x860x10x3D

Fa0/24SA32768000f.2032.5aaf5s0x860x20x3D

swicth#showlacp6counters

LACPDUsMarkerMarkerResponseLACPDUs

PortSentRecvSentRecvSentRecvPktsErr

---------------------------------------------------------------------

Channelgroup:6

Fa0/232816260301100##这里可以看到流量是平均分担的.

Fa0/242818260503300