在 Catalyst 交換器之間設定 802.1Q 主幹連線

簡介

本檔案介紹執行Cisco IOS®軟體的Cisco Catalyst交換器之間IEEE 802.1Q(dot1q)主幹^的差異。

必要條件

需求

嘗試此組態之前，請確保符合以下要求：

• IEEE 802.1Q中繼知識

• 使用指令行介面(CLI)設定Catalyst 3560和Catalyst 6500/6000系列交換器的知識

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12.2(25)SEA的Catalyst 3560交換器

• 運行Cisco IOS軟體版本12.1(26)E1的Catalyst 6509交換機

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。如果您的網路運作中，請確保您瞭解任何指令可能造成的影響。

背景資訊

本檔案將提供執行Cisco IOS^®軟體的Cisco Catalyst 3550/3560/3750交換器與執行Cisco IOS軟體的Catalyst 6500/6000系列交換器或Catalyst 4500/4000系列交換器之間的IEEE 802.1Q(dot1q)主幹組態範例。主幹連線是在兩個裝置之間，透過點對點連結，從多個 VLAN 攜帶流量的方式。

實施乙太網中繼的兩種方法是：

• 交換器間連結通訊協定(ISL) — 思科專有通訊協定

• 802.1Q - IEEE標準

Catalyst元件

本檔案中的Catalyst 3560設定也適用於執行Cisco IOS軟體的Catalyst 3550/3750交換器。本檔案中的Catalyst 6500/6000設定也適用於執行Cisco IOS軟體的Catalyst 4500/4000系列交換器。

注意：請參閱以下文檔以瞭解各種Catalyst交換機所支援的中繼方法：

• 在Catalyst交換機上實施中繼的系統要求

注意：本文檔僅包含交換機的配置檔案和相關示例命令的 show 輸出。有關如何在Catalyst交換器之間設定802.1Q主幹的詳細資訊，請參閱以下檔案：

• 配置VLAN - Catalyst 3560系列交換器的配置VLAN中繼部分

• 配置第2層乙太網介面 — 運行Cisco IOS軟體的Catalyst 4500系列交換機的瞭解VLAN Trunk部分

背景理論

IEEE 802.1Q使用內部標籤機制。中繼裝置插入一個4位元組的標籤以標識幀所屬的VLAN，然後重新計算幀校驗序列(FCS)。如需詳細資訊，請參閱以下檔案：

• InterSwitch鏈路和IEEE 802.1Q幀格式

• Catalyst 4500/4000、5500/5000和6500/6000系列交換器（使用802.1Q封裝和Cisco CatOS系統軟體）之間中繼的802.1Q中繼的基本特徵部分

注意：下面是此配置需要記住的重要說明：

• Catalyst 3550/3560/3750系列交換器上的任何乙太網路介面都可以支援802.1Q和ISL封裝。預設情況下，Catalyst 3550交換機上的乙太網介面是第2層(L2)埠。

• Catalyst 6500/6000系列交換器上的任何乙太網路連線埠均可支援802.1Q和ISL封裝。

• 預設情況下，運行Cisco IOS軟體的Catalyst 4500系列交換機支援ISL和802.1Q中繼模式。除了在WS-X4418-GB和WS-X4412-2GB-T模組上阻塞千兆埠外，所有介面均支援此功能。這些埠不支援ISL，僅支援802.1Q中繼。埠3到18阻塞了WS-X4418-GB模組上的Gigabit埠。埠1到12阻塞了WS-X4412-2GB-T模組上的Gigabit埠。

註：如果埠與背板的連線超額使用，則該埠為阻塞埠。

• Catalyst 6500/6000和Catalyst 4500平台之間的主要區別是預設介面組態。執行Cisco IOS軟體的Catalyst 6500/6000交換器上的介面處於關閉模式，預設為第3層(L3)路由連線埠。執行Cisco IOS軟體的Catalyst 4500/4000交換器已啟用所有介面。預設情況下，介面是L2交換機埠。

• 在Catalyst 3750交換器上的主幹介面上使用802.1Q封裝時，輸出上可見殘餘訊息，因為 show interface Catalyst 3750交換器會將有效802.1Q封裝封包（包括q標籤的61-64位元組）計為過小的訊框，即使這些封包已正確轉送。如需更多詳細資訊，請參閱Cisco錯誤ID CSCec14238 . 

附註：只有完成註冊的思科使用者有權存取思科內部工具與資訊。

設定

本節提供用於設定本文件中所述功能的資訊。

注意：使用命令查詢工具可獲取本節中使用的命令的詳細資訊。

附註：只有完成註冊的思科使用者有權存取思科內部工具與資訊。

網路圖表

此文件使用以下網路設定：

註:Catalyst 3560上的Gigabit乙太網路介面是10/100/1000 Mbps交涉乙太網路介面。因此，在此網路圖中，Catalyst 3560上的Gigabit連線埠連線到Catalyst 6500上的快速乙太網路(100 Mbps)連線埠。

網路圖表

組態

本檔案會使用以下設定：

• Catalyst 3560交換器

• Catalyst 6500交換器

!--- Notice: This example creates VLAN 1 and VLAN 2 
!--- and sets the VLAN Trunk Protocol (VTP) mode to transparent. Use your 
!--- network as a basis and set the VTP mode accordingly. For more details, 
!--- refer to Configuring VLANs.


 version 12.2 
 no service pad 
 service timestamps debug uptime 
 service timestamps log uptime 
 no service password-encryption 
 ! 
 hostname 3560 
 ! 

!--- This is the privileged mode password for the example.

 enable password mysecret
 ! 
 ip subnet-zero  
 ! 
 vtp mode transparent
 ! 

!--- VLAN 2 is created. This is visible only when you set VTP mode 
!--- to transparent. 

 vlan 2
 !

 ! 

!--- The Gigabit Ethernet interface on the Catalyst 3560 is a 10/100/1000 Mbps 
!--- negotiated Ethernet interface. Therefore, the Gigabit port on the 
!--- Catalyst 3560 is connected to a Fast Ethernet port on the Catalyst 6500. 
!--- Configure the trunk on the Gigabit Ethernet 0/1 interface.

 interface GigabitEthernet0/1 

!--- Configure trunk encapsulation as dot1q. 
!--- For details on trunking, refer to Configuring VLANs.

 switchport trunk encapsulation dot1q 

!--- Enable trunking on the interface.

 switchport mode trunk 
 no ip address 
 snmp trap link-status 
 !
 !

!--- Interfaces Gigabit Ethernet 0/2 through 0/5 are placed in VLAN 1. 
!--- In order to configure the interface as an L2 port, 
!--- refer to the Configuring Ethernet Interfaces section 
!--- of Configuring Interface Characteristics. All L2 ports are placed 
!--- in VLAN 1, by default.

 interface GigabitEthernet0/2 
 switchport mode access
 no ip address 
 snmp trap link-status 
 ! 
 interface GigabitEthernet0/3
 switchport mode access
 no ip address 
 snmp trap link-status 
 !
 !
 interface GigabitEthernet0/4 
 switchport mode access 
 no ip address 
 snmp trap link-status 
 ! 
 interface GigabitEthernet0/5 
 switchport mode access 
 no ip address 
 snmp trap link-status 
 ! 
 !

!--- Interfaces Gigabit Ethernet 0/6 through 0/12 are placed in VLAN 2.

 interface GigabitEthernet0/6 
 switchport access vlan 2 
 switchport mode access
 no ip address 
 snmp trap link-status 
 ! 
 
!--- Output suppressed.

 ! 
 interface GigabitEthernet0/12 
 switchport access vlan 2 
 switchport mode access 
 no ip address 
 snmp trap link-status 
 ! 
 interface Vlan1

!--- This is the IP address for management.

 ip address 10.1.1.1 255.255.255.0 
 ! 
 ip classless 
 ip http server 
 ! 
 ! 
 line con 0 
 transport input none 
 line vty 0 4 

!--- This is the privileged mode password for the example.

 password mysecret
 login 
 line vty 5 15 
 login 
 ! 
 end

!--- Notice: This example creates VLAN 1 and VLAN 2 and sets 
!--- the VTP mode to transparent. Use your network as a basis and set the VTP 
!--- mode accordingly. For more details, refer to Configuring VLANs.


 Current configuration : 4812 bytes
 version 12.1 
 service timestamps debug uptime 
 service timestamps log uptime 
 no service password-encryption 
 ! 
 hostname Cat6500 
 ! 
 vtp mode transparent
 ip subnet-zero
 !
 !
 mls flow ip destination 
 mls flow ipx destination 
 !

!--- This is the privileged mode password for the example.

 enable password mysecret
 ! 
 redundancy 
 mode rpr-plus
 main-cpu 
 auto-sync running-config
 auto-sync standard 
  
 ! 
 ! 

!--- This enables VLAN 2.

 vlan 2
 !
 !

 
 interface GigabitEthernet1/1 
 no ip address 
 shutdown 
 ! 
 interface GigabitEthernet1/2 
 no ip address 
 shutdown 
 ! 

!--- The Gigabit Ethernet interface on the Catalyst 3560 is a 10/100/1000 Mbps 
!--- negotiated Ethernet interface. Therefore, the Gigabit port on the Catalyst 3560 
!--- is connected to a Fast Ethernet port on the Catalyst 6500.

 interface FastEthernet3/1 
 no ip address 

!--- You must issue the switchport command once, 
!--- without any keywords, in order to configure the interface as an L2 port for the 
!--- Catalyst 6500 series switch that runs Cisco IOS Software. 
!--- On a Catalyst 4500 series switch that runs Cisco IOS Software, all ports are L2 
!--- ports by default. Therefore, if you do not change the default configuration, 
!--- you do not need to issue the switchport command. 
!--- For more details, refer to  Configuring Layer 2 Ethernet Interfaces 
!--- for the Catalyst 4500 series switch that runs Cisco IOS Software.


 switchport 

!--- Configure trunk encapsulation as dot1q. 
!--- For more details on trunking, refer to 
!--- Configuring LAN Ports for Layer 2 Switching for the Catalyst 6500 series switch 
!--- that runs Cisco IOS Software, or  Configuring Layer 2 Ethernet Interfaces 
!--- for the Catalyst 4500/4000 series switch that runs Cisco IOS Software.

 switchport trunk encapsulation dot1q 


!--- Enable trunking on the interface.


 switchport mode trunk 
 ! 

!--- Configure interfaces Fast Ethernet 3/2 through 3/24 to be in access mode. 
!--- By default, all access ports are configured in VLAN 1. 
!--- For more details, refer to Configuring LAN Ports for Layer 2 Switching
!--- for the Catalyst 6500 series switch that runs Cisco IOS Software, or 
!--- Configuring Layer 2 Ethernet Interfaces for the Catalyst 4500/4000 series 
!--- switch that runs Cisco IOS Software.

 interface FastEthernet3/2
 no ip address
 switchport
 switchport mode access
 ! 
 

!--- Output suppressed.

 !
 interface FastEthernet3/24
 no ip address 
 switchport 
 switchport mode access
 !

!--- Fast Ethernet 3/25 through 3/48 are placed in VLAN 2. 
!--- For more details, refer to Configuring LAN Ports for Layer 2 Switching 
!--- for the Catalyst 6500 series switch that runs Cisco IOS Software, 
!--- or Configuring Layer 2 Ethernet Interfaces for the Catalyst 4500/4000 
!--- series switch that runs Cisco IOS Software.

 interface FastEthernet3/25
 no ip address 
 switchport 
 switchport access vlan 2 
 switchport mode access 
 ! 
  

!--- Output suppressed.

 ! 
 interface FastEthernet3/48
 no ip address 
 switchport 
 switchport access vlan 2 
 switchport mode access 
 ! 
 ! 
 interface Vlan1 

!--- This is the IP address for management.

 ip address 10.1.1.2 255.255.255.0 
 ! 
 !
 ip classless 
 no ip http server 
 ! 
 ! 
 ip classless
 ip http server
 ! 
 line con 0 
 exec-timeout 0 0 
 transport input none 
 line vty 0 4 

!--- This is the Telnet password for the example.

 password mysecret
 login 
 
 ! 
 end 

註：如果將介面分配給不存在的VLAN，則該介面將關閉，直到您在VLAN資料庫中建立VLAN。有關詳細資訊，請參閱配置VLAN的建立或修改乙太網VLAN部分。

驗證

使用本節內容，確認您的組態是否正常運作。

輸出直譯器工具(OIT)支援某些 show 命令。使用OIT檢視命令輸出的 show 分析。

附註：只有完成註冊的思科使用者有權存取思科內部工具與資訊。

在Catalyst 3550/3560/3750/6500/4500交換器上，使用以下命令：

• show interfacesinterface_typemodule/porttrunk

• show interfacesinterface_typemodule/portswitchport

• show vlan

• show vtp status

命令 show 輸出示例

Catalyst 3560交換器

• show interfaces interface_type module/port trunk — 此命令顯示介面的TRUNK組態以及流量能夠通過TRUNK傳輸的VLAN編號。

  3560# show interface gigabitethernet 0/1 trunk
   
  Port      Mode         Encapsulation  Status        Native vlan
  Gi0/1     on           802.1q         trunking      1
   
  Port      Vlans allowed on trunk
  Gi0/1     1 4094
   
  Port      Vlans allowed and active in management domain
  Gi0/1     1-2
   
  Port      Vlans in spanning tree forwarding state and not pruned
  Gi0/1     1-2

• show interfaces interface_type module/port switchport — 此命令顯示介面的交換機埠配置。

  在顯示中，檢查Operational Mode和Operational Trunk Encapsulation欄位。

  3560# show interface gigabitethernet 0/1 switchport
  Name: Gi0/1
  Switchport: Enabled
  Administrative Mode: trunk
  Operational Mode: trunk
  Administrative Trunking Encapsulation: dot1q
  Operational Trunking Encapsulation: dot1q
  Negotiation of Trunking: On
  Access Mode VLAN: 1 (default)
  Trunking Native Mode VLAN: 1 (default)
  Voice VLAN: none
  Administrative private-vlan host-association: none 
  Administrative private-vlan mapping: none 
  Administrative private-vlan trunk native VLAN: none
  Administrative private-vlan trunk encapsulation: dot1q
  Administrative private-vlan trunk normal VLANs: none
  Administrative private-vlan trunk private VLANs: none
  Operational private-vlan: none
  Trunking VLANs Enabled: ALL
  Pruning VLANs Enabled: 2-1001
  Capture Mode Disabled
  Capture VLANs Allowed: ALL  
  Protected: false
  Unknown unicast blocked: disabled
  Unknown multicast blocked: disabled
  Appliance trust : none 

• show vlan — 此命令會提供有關VLAN以及屬於特定VLAN的連線埠的資訊。

  3560# show vlan
   
  VLAN Name                             Status    Ports
  ---- -------------------------------- --------- -------------------------------
  1    default                          active    Gi0/2, Gi0/3, Gi0/4, Gi0/5
  2    VLAN0002                         active    Gi0/6, Gi0/7, Gi0/8, Gi0/9
                                                              Gi0/10, Gi0/11, Gi0/12
  
  1002 fddi-default                     act/unsup
  1003 token-ring-default               act/unsup
  1004 fddinet-default                  act/unsup
  1005 trnet-default                    act/unsup
  
  !--- Output suppressed.
  
  

  註：輸出中顯示的埠僅為訪問埠。但設定為中繼且處於「notconnected」狀態的連線埠也會顯示在show vlan 輸出中。

• show vtp status — 此命令顯示有關VTP管理域、狀態和計數器的常規資訊。

  3560# show vtp status
  VTP Version : 2 
  Configuration Revision : 0 
  Maximum VLANs supported locally : 1005 
  Number of existing VLANs : 6 
  VTP Operating Mode : Transparent      
  VTP Domain Name : 
  VTP Pruning Mode : Disabled 
  VTP V2 Mode : Disabled 
  VTP Traps Generation : Disabled 
  MD5 digest : 0x4A 0x55 0x17 0x84 0xDB 0x99 0x3F 0xD1 
  Configuration last modified by 10.1.1.1 at 0-0-00 00:00:00
  
  3560# ping 10.1.1.2 
  Type escape sequence to abort. 
  Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds: 
  !!!!! 
  Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms 
  3560#

Catalyst 6500交換器

• show interfaces interface_type module/porttrunk — 此命令顯示介面的TRUNK組態以及流量能夠通過TRUNK傳輸的VLAN編號。

Cat6500# show interfaces fastethernet 3/1 trunk
 
Port      Mode         Encapsulation  Status        Native vlan
Fa3/1     on           802.1q         trunking      1
 
Port      Vlans allowed on trunk
Fa3/1     1 4094
 
Port      Vlans allowed and active in management domain
Fa3/1     1-2
 
Port      Vlans in spanning tree forwarding state and not pruned
Fa3/1     1-2

• show interfacesinterface_typemodule/portswitchport — 此命令顯示介面的交換機埠配置。 在顯示中，檢查Operational Mode和Operational Trunk Encapsulation欄位。  

cat6500# show interface fastethernet 3/1 switchport 
Name: Fa3/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Administrative private-vlan host-association: none 
Administrative private-vlan mapping: none 
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL

• show vlan — 此命令會提供有關VLAN以及屬於特定VLAN的連線埠的資訊。

Cat6500# show vlan
 
VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa3/2, Fa3/3, Fa3/4, Fa3/5
                                                Fa3/6, Fa3/7, Fa3/8, Fa3/9
                                                Fa3/10, Fa3/11, Fa3/12, Fa3/13
                                                Fa3/14, Fa3/15, Fa3/16, Fa3/17
                                                Fa3/18, Fa3/19, Fa3/20, Fa3/21
                                                Fa3/22, Fa3/23, Fa3/24
2    VLAN0002                         active    Fa3/25, Fa3/26, Fa3/27, Fa3/28
                                                Fa3/29, Fa3/30, Fa3/31, Fa3/32
                                                Fa3/33, Fa3/34, Fa3/35, Fa3/36
                                                Fa3/37, Fa3/38, Fa3/39, Fa3/40
                                                Fa3/41, Fa3/42, Fa3/43, Fa3/44
                                                Fa3/45, Fa3/46, Fa3/47, Fa3/48
1002 fddi-default                      act/unsup
1003 token-ring-default                act/unsup
1004 fddinet-default                   act/unsup
1005 trnet-default                     act/unsup


!--- Output suppressed.

註：顯示的埠只是已配置為第2層非中繼（訪問）埠的那些埠。設定為中繼且處於「notconnected」狀態的連線埠也會顯示在show vlan 輸出中。有關詳細資訊，請參閱為第2層交換配置LAN埠中的為第2層交換配置LAN介面。

• show vtp status — 此命令顯示有關VTP管理域、狀態和計數器的常規資訊。

  Cat6500# show vtp status
  VTP Version                     : 2
  Configuration Revision          : 0
  Maximum VLANs supported locally : 1005
  Number of existing VLANs        : 6
  VTP Operating Mode              : Transparent
  VTP Domain Name                 :
  VTP Pruning Mode                : Disabled
  VTP V2 Mode                     : Disabled
  VTP Traps Generation            : Disabled
  MD5 digest                      : 0xBF 0x86 0x94 0x45 0xFC 0xDF 0xB5 0x70
  Configuration last modified by 10.1.1.2 at 0-0-00 00:00:00

• ping

  Cat6500# ping 10.1.1.1
   
  Type escape sequence to abort.
  Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
  !!!!!
  Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

疑難排解

目前尚無適用於此組態的具體疑難排解資訊。有關中繼和802.1Q配置的常見問題，請參閱使用802.1Q封裝和Cisco CatOS系統軟體的Catalyst 4500/4000、5500/5000和6500/6000系列交換機之間的中繼文檔的常見錯誤部分。

相關資訊

• 使用 PortFast 和其他命令修復工作站啟動連線延遲
• Catalyst 3560系列交換器設定指南
• Catalyst 4500系列交換器設定指南
• Catalyst 6500系列交換器設定指南
• 思科技術支援與下載