在Catalyst L2固定組態交換器與執行CatOS的Catalyst交換器之間設定EtherChannel和802.1Q中繼

簡介

本文提供設定EtherChannel連結的範例組態和命令結構，EtherChannel連結是Catalyst第2層(L2)固定組態交換器（包括2950/2955/2970/2940/2900XL/3500XL交換器）和執行Catalyst OS(CatOS)的Catalyst 4500/4000交換器之間的主干連結。 在此案例中，您可以使用執行CatOS的任何Catalyst 4500/4000、5500/5000或6500/6000系列交換器設定Catalyst L2固定組態交換器，以取得相同的結果。隨著快速乙太網在當前網路中的普及，示例配置使用快速乙太網。該示例將每台交換機的兩個快速乙太網埠捆綁到一個快速EtherChannel(FEC)中，並在FEC頂部配置IEEE 802.1Q(dot1q)中繼。

必要條件

需求

本文使用相同的術語EtherChannel來指代FEC、Gigabit EtherChannel(GEC)、連線埠通道、通道和連線埠群組。有關如何配置交換機上的EtherChannel的詳細資訊，請參閱以下文檔：

• 在Catalyst 4000交換器上設定快速EtherChannel和Gigabit EtherChannel

• Catalyst 2950交換器上設定EtherChannel

• Catalyst 2950/2955交換器上設定EtherChannel

• Catalyst 2970交換器上設定EtherChannel

• Catalyst 2940交換器上設定EtherChannel

• 在Catalyst 2900XL/3500XL交換器和CatOS交換器之間設定EtherChannel

採用元件

本文中的資訊係根據以下軟體和硬體版本：

• 執行Cisco IOS®軟體版本12.1(6)EA2c的Catalyst 2950

• 執行Cisco IOS軟體版本12.1(12c)EA1的Catalyst 2955

• 執行Cisco IOS軟體版本12.1(22)EA1的Catalyst 2940

• 執行Cisco IOS軟體版本12.1(19)EA1c的Catalyst 2970

• 執行Cisco IOS軟體版本12.0(5)WC9的Catalyst 2900XL/3500XL

• 執行CatOS版本8.4.1的Catalyst 4000

本文中的資訊是根據特定實驗室環境內的裝置所建立。文中使用到的所有裝置皆從已清除（預設）的組態來啟動。如果您的網路正在作用，請確保您已瞭解任何指令可能造成的影響。

慣例

如需文件慣例的詳細資訊，請參閱思科技術提示慣例。

背景理論

使用Catalyst L2固定組態交換器和執行CatOS的任何Catalyst 4500/4000系列產品(Catalyst 4003/4006/2948G/2980G)時，請記住，交換器僅支援dot1q中繼封裝。其他Catalyst平台同時支援dot1q和交換器間連結通訊協定(ISL)。 雖然dot1q是IEEE標準，但ISL是Cisco專有協定。只有Cisco硬體能夠支援ISL中繼封裝。如果您使用其他Cisco交換平台（例如Catalyst 5500/5000或Catalyst 6500/6000），並需要判斷哪個中繼方法具有支援，請發出以下命令：

• show port capabilities mod/port

如需特定連線埠的詳細資訊，以及特定連線埠具有的功能（例如dot1q、ISL和連線埠通道），請參閱：

• show port capabilities

連結彙總控制通訊協定(LACP)和連線埠彙總通訊協定(PAgP)

EtherChannel可自動設定為連線埠彙總通訊協定(PAgP)或連結彙總控制通訊協定(LACP)。 您也可以手動設定EtherChannel。PAgP是思科專有協定，您只能在思科交換機和授權供應商許可支援PAgP的交換機上運行。IEEE 802.3ad定義了LACP。LACP允許思科交換機管理符合802.3ad協定的交換機之間的乙太網通道。最多可配置16個埠以形成通道。其中8個埠處於主用模式，另外8個埠處於備用模式。當任何活動埠發生故障時，備用埠變為活動狀態。備用模式僅適用於LACP，不適用於PAgP。

如果您使用其中一種協定，交換機將獲知能夠支援PAgP或LACP的合作夥伴身份並獲知每個介面的功能。然後，交換機將具有相似配置的介面動態分組到單個邏輯鏈路（通道或聚合埠）；交換機將這些介面組基於硬體、管理和埠引數限制。例如，PAgP使用相同的速度、雙工模式、本徵VLAN、VLAN範圍以及中繼狀態和型別對介面進行分組。PAgP將鏈路分組到EtherChannel後，PAgP會將該組作為單個交換機埠新增到生成樹中。

PAgP和LACP模式

本節列出channel-group介面組態指令的使用者可設定的EtherChannel模式。交換機介面僅與具有auto或desirable模式配置的夥伴介面交換PAgP資料包。交換機介面僅與具有主用模式或被動模式配置的夥伴介面交換LACP資料包。具有on模式配置的介面不會交換PAgP或LACP資料包。

• active — 將介面置於主動協商狀態，在該狀態下，介面通過傳送LACP資料包開始與其他介面的協商。

• auto — 將介面置於被動協商狀態，在該狀態下，介面將響應介面接收到的PAgP資料包，但不會啟動PAgP資料包協商。此設定可將PAgP資料包的傳輸降至最低。

• desirable — 將介面置於主動協商狀態，在該狀態下，介面通過傳送PAgP資料包開始與其他介面協商。

• on — 強制介面進入不帶PAgP或LACP的EtherChannel。若使用on模式，則只有在on模式的介面群組具有與on模式中的另一個介面群組的連線時，才存在可用的EtherChannel。

• passive — 將介面置於被動協商狀態，在該狀態下，介面將響應介面收到的LACP資料包，但不啟動LACP資料包協商。此設定可將LACP資料包的傳輸降至最低。

只有三個有效組合可以運行LACP鏈路聚合，如下表所示：

注意：預設情況下，配置LACP通道時，LACP通道模式是被動的。

PAgP限制

PAgP有助於自動建立FEC連結。PAgP資料包在支援FEC的埠之間傳輸以協商通道的形成。PAgP中特意引入了一些限制。限制如下：

• PAgP不會在具備動態VLAN配置的埠上形成捆綁包。PAgP要求通道中的所有埠屬於同一個VLAN，或者這些埠具有中繼埠配置。當捆綁包已存在並且您修改了埠的VLAN時，捆綁包中的所有埠都會更改以匹配該VLAN。

• PAgP不對以不同速度或埠雙工運行的埠進行分組。如果當套件組合存在時變更速度和雙工，PAgP會變更套件組合中所有連線埠的連線埠速度和雙工。

• PAgP模式為off、auto、desirable和on。只有auto-desirable、desirable-desirable和on-on組合才允許形成通道。如果通道一端的裝置（例如路由器）不支援PAgP，則另一端的裝置必須將PAgP設定為on。Catalyst 2950交換器支援PAgP，以便與Cisco IOS軟體版本12.1(6)EA2或更新版本進行通道交涉。Cisco IOS軟體版本12.0僅支援靜態配置。所有執行CatOS的Catalyst交換器支援PAgP通訊協定通道交涉。

動態Trunk通訊協定(DTP)

中繼協定有多種型別。如果埠可以成為中繼，它還可以自動中繼埠。在某些情況下，埠甚至可以協商要在埠上使用的中繼型別。這種與另一台裝置協商中繼方法的能力名為動態中繼協定(DTP)。

Catalyst 2950交換器使用Cisco IOS軟體版本12.1(6)EA2或更新版本支援動態中繼的DTP。Cisco IOS軟體版本12.0僅支援靜態配置。所有執行CatOS的Catalyst交換器支援DTP。

設定

本節提供用於設定本文件中所述功能的資訊。

注意：要查詢有關本文檔中使用的命令的其他資訊，請使用命令查詢工具 (僅限註冊客戶)。

網路圖表

本檔案會使用以下網路設定：

組態

本檔案會使用以下設定：

• 執行CatOS的Catalyst 4000上的LACP

• 執行Cisco IOS軟體的Catalyst L2固定組態交換器上的LACP

• 執行Cisco IOS軟體的Catalyst L2固定組態交換器上的PAgP

• 執行CatOS的Catalyst 4000上的PAgP

在執行CatOS的Catalyst 4000上設定LACP

Cat4003 (enable) show channelprotocol          
         Channel
         Module Protocol
         ------- --------
         2       PAGP
         Cat4003 (enable)


!--- By default, all ports on a Catalyst 4500/4000 use channel protocol PAgP. !--- So, to run LACP, you must change the channel protocol to LACP. On switches !--- that run CatOS, you can only change the channel mode per module. In this !--- example, the command set channelprotocol lacp module_number !--- changes the channel mode for slot 2. Use the show channelprotocol command to !--- verify the changes. 

Cat4003 (enable) set channelprotocol lacp 2
Mod 2 is set to LACP protocol.
Cat4003 (enable)
         
Cat4003 (enable) set port lacp-channel 2/1-2
Port(s) 2/1-2 are assigned to admin key 80.
Cat4003 (enable)


!--- There is a parameter exchange in the LACP packet. The parameter is !--- the admin key. A channel can only form between ports that have !--- the same admin key. In this example, both ports have assignment to the same group. !--- (The random assignment is admin key 80.) !--- Keep in mind that the admin key is only locally significant. In other words, !--- the admin key must be the same only for ports within the switch and is not a factor !--- between different switches.


Cat4003 (enable) set port lacp-channel 2/1-2 mode active
Port(s) 2/1-2 channel mode set to active.
Cat4003 (enable)  

To form the channel change the LACP channel mode          
to active state on one or both of the sides.

Cat4003 (enable) set trunk 2/1 desirable dot1q
Port(s) 2/1-2 trunk mode set to desirable.
Port(s) 2/1-2 trunk type set to dot1q.
Cat4003 (enable) 


!--- Configure the ports to the desirable trunk mode that makes the ports actively !--- attempt to convert the link to a trunk link. The ports become trunk ports if !--- the neighbor ports are in on, desirable, or auto mode.


Cat4003 (enable) show config
This command shows non-default configurations only.
Use 'show config all' to show both default and non-default configurations.
.................

.............................

..

begin

!--- Output suppressed.

#channelprotocol
set channelprotocol lacp 2
!
#port channel
set port lacp-channel 2/1-2 80
!

!--- Output suppressed.


#module 2 : 48-port 10/100/1000 Ethernet
set trunk 2/1 desirable dot1q 1-1005,1025-4094
set trunk 2/2 desirable dot1q 1-1005,1025-4094
! 

!--- Output suppressed.

在執行Cisco IOS軟體的Catalyst L2固定組態交換器上設定LACP

Catalyst L2固定組態交換器平台的設定命令相同。為使檔案長度保持合理，本檔案只會顯示其中一個平台(Catalyst 2955)的組態。 但是，在所有Catalyst L2固定配置交換機平台上對所有命令進行了測試。

CAT2955# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
CAT2955(config)# interface fastethernet 0/9
CAT2955(config-if)# channel-group 1 mode active
Creating a port-channel interface Port-channel 1 

Assign the interface to a channel group, and specify the LACP mode. 

CAT2955(config-if)#
6d08h: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/9,changed state to down
6d08h: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/9,changed state to up
6d08h: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up
6d08h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1,changed state to up
CAT2955(config-if)# interface fastethernet 0/10
CAT2955(config-if)# channel-group 1 mode active 
CAT2955(config-if)#
6d08h: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/10,changed state to down
6d08h: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/10,changed state to up
CAT2955(config-if)# interface port-channel 1
CAT2955(config-if)# switchport mode trunk

Configuring the port channel interface to be a trunk pulls fa 0/9-10 in.

CAT2955(config-if)# ^Z
CAT2955# show run
6d08h: %SYS-5-CONFIG_I: Configured from console by consolerun
         Building configuration... 

!--- Output suppressed.

!
interface Port-channel1
 switchport mode trunk
 no ip address
 flowcontrol send off
 fcs-threshold 0
!

!--- Output suppressed.

interface FastEthernet0/9
 switchport mode trunk
 no ip address
 channel-group 1 mode active
!
interface FastEthernet0/10
 switchport mode trunk
 no ip address
 channel-group 1 mode active
!

!--- Output suppressed.

end

CAT2955#

在執行Cisco IOS軟體的Catalyst L2固定組態交換器上設定PAgP

5-2950# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
5-2950(config)# interface fastethernet0/1
5-2950(config-if)# channel-group 1 mode desirable
Creating a port-channel interface Port-channel1

!--- The software dynamically creates the port channel interface.

5-2950(config-if)#
*Mar 16 13:50:56.185: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed 
state to down
*Mar 16 13:50:57.013: %EC-5-BUNDLE: Interface Fa0/1 joined port-channel Po1
*Mar 16 13:50:58.053: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed 
state to up
*Mar 16 13:50:59.021: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up
*Mar 16 13:51:00.021: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed 
state to up
5-2950(config-if)#
5-2950(config)# interface fastethernet0/2
5-2950(config-if)# channel-group 1 mode desirable
5-2950(config-if)#
5-2950(config-if)# interface port-channel 1

!--- Configuration of the port channel interface to be a trunk !--- pulls in Fast Ethernet 0/1 and 0/2.

5-2950(config-if)# switchport mode trunk 
*Mar 14 15:31:13.428: %DTP-5-TRUNKPORTON: Port Fa0/1 has become dot1q trunk  
*Mar 14 15:31:14.880: %EC-5-BUNDLE: Interface Fa0/1 joined port-channel Po1
*Mar 14 15:31:14.908: %EC-5-UNBUNDLE: Interface Fa0/2 left the port-channel Po1
*Mar 14 15:31:14.944: %EC-5-BUNDLE: Interface Fa0/2 joined port-channel Po1
*Mar 14 15:31:15.908: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed 
state to up
5-2950# show run
Building configuration...
Current configuration : 1608 bytes
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log datetime msec localtime
no service password-encryption
!
hostname 5-2950
!
!
clock timezone PST -8
ip subnet-zero
no ip finger
no ip domain-lookup
cluster enable SWITCH 0
!
!
!
interface Port-channel 1

!--- This is the port channel interface where you configure trunking that !--- the members of the channel group inherit.

 switchport mode trunk
!         
interface FastEthernet0/1
 switchport mode trunk
 channel-group 1 mode desirable

!--- Here, the channel group corresponds with interface port-channel 1.

!
interface FastEthernet0/2
 switchport mode trunk
 channel-group 1 mode desirable

!--- Here, the channel group corresponds with interface port-channel 1.

!
interface FastEthernet0/3
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!         
interface FastEthernet0/7
!

在執行CatOS的Catalyst 4000上設定PAgP

Console> (enable) set port channel 2/19-20 mode desirable
Port(s) 2/19-20 channel mode set to desirable.
Console> (enable) 2003 Jan 08 11:40:14 %PAGP-5-PORTFROMSTP:Port 2/19 left bridge port 2/19
2003 Jan 08 11:40:14 %PAGP-5-PORTFROMSTP:Port 2/20 left bridge port 2/20
2003 Jan 08 11:40:18 %PAGP-5-PORTTOSTP:Port 2/19 joined bridge port 2/19
2003 Jan 08 11:40:18 %PAGP-5-PORTTOSTP:Port 2/20 joined bridge port 2/20
 
Console> (enable) set trunk 2/19 desirable

!--- The set of the trunk on the first port of the channel !--- dynamically trunks all channel ports.


Port(s) 2/19-20 trunk mode set to desirable.
!
Console> (enable)

!--- The dot1q trunk adopts the port VLAN assignment (VLAN 1 by default) !--- as the native VLAN. If this switch were a Catalyst 5500/5000 or 6500/6000 switch !--- (which also supports ISL trunking), you would specify dot1q encapsulation here. !--- The Catalyst 2950 only supports dot1q.

驗證

本節提供的資訊可用於確認您的組態是否正常運作。

Output Interpreter Tool (僅供註冊客戶使用)支援某些show命令，這允許您檢視show命令輸出的分析。第2層固定組態交換器平台上的show命令相同，但輸出格式可能不同。

LACP配置的show輸出示例

Catalyst 2955交換器

CAT2955# show etherchannel summary
Flags:  D - down        P - in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        u - unsuitable for bundling
        U - in use      f - failed to allocate aggregator

 d - default port
   Number of channel-groups in use: 1
   Number of aggregators: 1

Group Port-channel Protocol Ports
   ------+-------------+-----------+-----------------------------------------------
   1 Po1(SU) LACP Fa0/9(P) Fa0/10(Pd) 

CAT2955#


CAT2955# show interfaces fastethernet 0/9 switchport 
Name: Fa0/9
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk (member of bundle Po1)
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Administrative private-vlan host-association: none 
Administrative private-vlan mapping: none 
Operational private-vlan: none 
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001

Protected: false

Voice VLAN: none (Inactive)
   Appliance trust: none

Catalyst 4000交換器

Cat4003 (enable) show lacp
Channel Id   Ports
-----------  -----------------------------------------------
417          2/1-2                                          

Cat4003 (enable) show lacp-channel 417
Channel Ports                                          Status     Channel
id                                                                Mode
------- ---------------------------------------------- ---------- --------------
    417 2/1-2                                          connected  active        
Cat4003 (enable)

Cat4003 (enable) show trunk
* - indicates vtp domain mismatch
# - indicates dot1q-all-tagged enabled on the port
Port      Mode         Encapsulation  Status        Native vlan
--------  -----------  -------------  ------------  -----------
 2/1      desirable    dot1q          trunking      1
 2/2      desirable    dot1q          trunking      1

Port Vlans allowed on trunk
   -------- ---------------------------------------------------------------------
   2/1 1-1005,1025-4094
   2/2 1-1005,1025-4094



Port Vlans allowed and active in management domain 
   -------- ---------------------------------------------------------------------
   2/1 1,10
   2/2 1,10



Port Vlans in spanning tree forwarding state and not pruned
   -------- ---------------------------------------------------------------------
   2/1 1,10
   2/2 1,10

Cat4003 (enable)

PAgP配置的show輸出示例

Catalyst 2950交換器

5-2950# show etherchannel summary
Flags:  D - down        P - in port-channel
        I - stand-alone s - suspended
        R - Layer3      S - Layer2
        U - port-channel in use
Group Port-channel  Ports
-----+------------+-----------------------------------------------------------
1     Po6(SU)     Fa0/1(P)   Fa0/2(P)   
 
5-2950# show interface fastethernet0/1 switchport
Name: Fa0/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk (member of bundle Po6)
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)

!--- This line shows that the trunk link is up.

Trunking VLANs Enabled: ALL

!--- This line shows that all VLANs trunk.

Pruning VLANs Enabled: 2-1001
 
Protected: false
 
Voice VLAN: none (Inactive)
Appliance trust: none

Catalyst 4000交換器

Console> show port channel 
Port  Status     Channel Admin       Ch Mode Group Id
----- ---------- -------------------- -----   -----
 2/19 connected  desirable silent      174     815
 2/20 connected  desirable silent      174     815
----- ---------- -------------------- ----- -----
Port  Device-ID                       Port-ID                   Platform
----- ------------------------------- ------------------------- ----------------
 2/19 5-2950                          Fa0/1                     cisco WS-C2950-24
 2/20 5-2950                          Fa0/2                     cisco WS-C2950-24
----- ------------------------------- ------------------------- ----------------

Console> (enable) show trunk
* - indicates vtp domain mismatch
Port      Mode         Encapsulation  Status        Native vlan
--------  -----------  -------------  ------------  -----------
 2/19     desirable    dot1q          trunking      1
 2/20     desirable    dot1q          trunking      1
 
Port      Vlans allowed on trunk
--------  ---------------------------------------------------------------------
 2/19     1-1005
 2/20     1-1005
 
Port      Vlans allowed and active in management domain 
--------  ---------------------------------------------------------------------
 2/19     1,100,300,350,450
 2/20     1,100,300,350,450
 
Port      Vlans in spanning tree forwarding state and not pruned
--------  ---------------------------------------------------------------------
 2/19     1,100,300,350,450
 2/20     1,100,300,350,450
Console> (enable)

疑難排解

目前尚無適用於此組態的具體疑難排解資訊。

相關資訊

• EtherChannel配置指南 配置交換機埠
• Catalyst 2950案頭交換器軟體組態設定指南12.1(6)EA2c
• 軟體配置指南(5.5)
• LAN 產品支援頁面
• LAN 交換支援頁面
• 技術支援 - Cisco Systems