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建立Port Channel(LACP&PAgP)

Cisco EtherChannel

1.   Cisco EtherChannel主要有兩種協定可選擇,分別為PAgP(Port Aggregation Protocol)LACP(Link Aggregation Control Protocol)

I.      PAgPCisco私有的協定,只能被用在Cisco自家的交換器之間。

II.    LACP則是由IEEE開放協定的標準(802.3ad),它可以用在不同廠牌之間的交換器,前提是需支援上述協定。

2.   依照不同的協定又有不同mode可以選擇



disables PAgP en LACP


disables PAgP en LACP and prevent the ports to form a port-channel


use PAgP in a passive mode, it will wait until a PAgP packet will be send


use LACP in a passive mode, it will wait until a PAgP packet will be send


use PAgP in an active mode, it will start to send PAgP packets


use LACP in an active mode, it will start to send LACP packets


3.     以下將使用LACP(802.3ad)通用協定來作範例


LACP (Link Aggregation Control Protocol) (Trunk Port)

1.     2SwitchEtherChannel設定

JLAB(config)# interface port-channel 1    //進入port-channel 1設定介面

JLAB(config-if)# interface range gi1/0/4-5    //進入gi1/0/4gi1/0/5共同介面

JLAB(config-if-range)# switchport trunk encapsulation dot1q    //套用trunk協定IEEE 802.1Q (或者用ISL)

JLAB(config-if-range)# switchport mode trunk    //設定trunk模式

JLAB(config-if-range)# switchport nonegotiate    //取消DTP及對方協議用的封面

JLAB(config-if-range)# channel-group 1 mode active    //設定LACP協定


JLAB# sh etherchannel

                Channel-group listing:



Group: 1


Group state = L2

Ports: 2   Maxports = 16

Port-channels: 1 Max Port-channels = 16

Protocol:   LACP


JLAB# sh etherchannel port-channel

                Channel-group listing:



Group: 1


                Port-channels in the group:



Port-channel: Po1    (Primary Aggregator)




Age of the Port-channel   = 0d:00h:07m:18s

Logical slot/port   = 10/1          Number of ports = 0

HotStandBy port = null

Port state          = Port-channel Ag-Not-Inuse

Protocol            =   LACP


JLAB# sh etherchannel summary

Flags:  D - down        P - in port-channel

        I - stand-alone s - suspended

        H - Hot-standby (LACP only)

        R - Layer3      S - Layer2

        U - in use      f - failed to allocate aggregator

        u - unsuitable for bundling

        w - waiting to be aggregated

        d - default port



Number of channel-groups in use: 1

Number of aggregators:           1


Group  Port-channel  Protocol    Ports


1      Po1(SD)         LACP      Gi1/0/4(D)  Gi1/0/5(D)



LACP (Link Aggregation Control Protocol) (Access Port)

1.     Switch連接主機端設定

JLAB(config)# interface port-channel 2    //進入port-channel 1設定介面

JLAB(config-if)# interface range fa/0/21-22    //進入gi1/0/4gi1/0/5共同介面

JLAB(config-if-range)# switchport mode access    //設定access模式

JLAB(config-if-range)# channel-group 1 mode active    //設定LACP協定


Remove the port channel and delete the associated channel group

1.     移除Port Channel

JLAB(config)# no interface port-channel channel-number



1.     不可在SwitchSwitch Stack設定超過48EtherChannel群組。

2.     設定同一組PAgP EtherChannel不可超過8個網路埠。

3.     設定同一組LACP EtherChannel上限可達16個網路埠,同時間只有8個埠是Active,其餘8個網路埠狀態為standby

4.     不可將同一個網路埠同時分配給多個群組。

5.     同一台SwtichSwitch Stack可同時設定多組PAgPLACP協定,但同一組EtherChannel群組只能擇1選擇。

6.     EtherChannel群組成員(網路埠)內避免以下設定

I.     Switched Port Analyzer (SPAN) destination port

II.    secure or reversed port

III.   private-VLAN port

7.     不可將群組內網路埠更改為IEEE 802.1x port


Verifying Port-Channel Configuration



switch# show interface port-channel channel-number

Displays the status of a port-channel interface.

switch# show lacp {counters |interface type slot/port |neighbor | port-channel |system-identifier}

Displays LACP information.

switch# show port-channel compatibility-parameters

Displays the parameters that must be the same among the member ports in order to join a port channel.

switch# show port-channel database [interface port-channelchannel-number]

Displays the aggregation state for one or more port-channel interfaces.

switch# show port-channel load-balance

Displays the type of load balancing in use for port channels.

switch# show port-channel summary

Displays a summary for the port-channel interfaces.

switch# show port-channel traffic

Displays the traffic statistics for port channels.

switch# show port-channel usage

Displays the range of used and unused channel numbers.


James Chan,
2012年12月12日 下午5:15