在 Catalyst 2900XL/3500XL/2950 交换机上使用外部路由器配置 VLAN 间路由和 ISL/802.1Q 中继

注意： 以下屏幕截图显示了在 3512XL 交换机上输入的命令。命令之间的备注添加为蓝色斜体，旨在解释特定命令和步骤。

!-- Set the privileged mode


!-- and Telnet password on the switch.

switch#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)#hostname 3512xl
3512xl(config)#enable password mysecret
3512xl(config)#line vty 0 4
3512xl(config-line)#login
3512xl(config-line)#password mysecret
3512xl(config-line)#exit
3512xl(config)#no logging console
3512xl(config)#^Z


!-- Set the IP address and default gateway for VLAN1 for management purposes.

3512xl#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
3512xl(config)#int vlan 1
3512xl(config-if)#ip address 10.10.10.2 255.255.255.0
3512xl(config-if)#exit
3512xl(config)#ip default-gateway 10.10.10.1
3512xl(config)#end

!-- Set the VTP Mode. !-- In our example, we have set the mode to be transparent. !-- Depending on your network, set the VTP Mode accordingly. !-- For details on VTP, !-- refer to !-- Creating and Maintaining VLANs on Catalyst 2900XL and 3500XL Switches.

3512xl#vlan database
3512xl(vlan)#vtp transparent
Setting device to VTP TRANSPARENT mode.


!-- Adding VLAN2. VLAN1 already exists by default.

3512xl(vlan)#vlan 2
VLAN 2 added:
Name: VLAN0002
3512xl(vlan)#exit
APPLY completed.
Exiting....


!-- Enable trunking on the interface fastEthernet 0/1.

3512xl#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
3512xl(config)#int fastEthernet 0/1
3512xl(config-if)#switchport mode trunk


!-- Enter the trunking encapsulation as either isl

3512xl(config-if)#switchport trunk encapsulation isl

!-- or as dot1q:


3512xl(config-if)#switchport trunk encapsulation dot1q

!-- In case of 2940/2950 series switches, none of the above two commands are used, !-- 2940/2950 series switches only support 802.1q encapsulation which is configured automatically, !-- when trunking is enabled on the interface by using switchport mode trunk command. !-- In case of dot1q, you need to make sure that !-- the native VLAN matches across the link. !-- On 3512XL, by default, the native VLAN is 1. !-- Depending on your network needs, you may change !-- the native VLAN to be other than VLAN1, !-- but it is very important that you change the native VLAN !-- on the router accordingly. !-- You may change the native VLAN, if needed, by using the following command: !-- 3512xl(config-if)#switchport trunk native vlan <vlan ID> !-- Allow all VLANs on the trunk.

3512xl(config-if)#switchport trunk allowed vlan all
3512xl(config-if)#exit


!-- The following set of commands will place FastEthernet 0/2 !-- into VLAN2 and enable portfast on the interface.

3512xl(config)#int fastEthernet 0/2
3512xl(config-if)#switchport access vlan 2
3512xl(config-if)#spanning-tree portfast
3512xl(config-if)#exit


!-- FastEthernet 0/3 is already in VLAN1 by default. !-- Enable portfast on the interface.

3512xl(config)#int fastEthernet 0/3
3512xl(config-if)#spanning-tree portfast
3512xl(config-if)#^Z

!-- For details on why to enable portfast, !-- refer to: !-- Using PortFast and Other Commands to Fix Workstation Startup Connectivity Delays. !-- Remember to save the configuration.

3512xl#write memory
Building configuration...

3512xl#

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

3512xl#show running-config
Building configuration...

Current configuration:

!
version 12.0
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname 3512xl
!
no logging console
enable password mysecret
!
!
!
!
!
ip subnet-zero
!
!
!
interface FastEthernet0/1
  switchport mode trunk
!

!-- If 802.1Q is configured, !-- you will instead see the following output !-- under interface FastEthernet0/1: !-- interface FastEthernet0/1 !-- switchport trunk encapsulation dot1q !-- switchport mode trunk

!
interface FastEthernet0/2
 switchport access vlan 2
 spanning-tree portfast
!
interface FastEthernet0/3
 spanning-tree portfast
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/7
!
interface FastEthernet0/8
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface GigabitEthernet0/1
!
interface GigabitEthernet0/2
!
interface VLAN1
 ip address 10.10.10.2 255.255.255.0
 no ip directed-broadcast
 no ip route-cache
!
ip default-gateway 10.10.10.1
!
line con 0
 transport input none
 stopbits 1
line vty 0 4
 password mysecret
 login
line vty 5 15
 login
!
end

注意： 以下屏幕截图显示了在 Cisco 2600 路由器上输入的命令。命令之间的备注添加为蓝色斜体，旨在解释特定命令和步骤。

!-- Set the privileged mode !-- and Telnet password on the router.

Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#hostname c2600

c2600(config)#enable password mysecret
c2600(config)#line vty 0 4
c2600(config-line)#login
c2600(config-line)#password mysecret
c2600(config-line)#exit
c2600(config)#no logging console
c2600(config)#^Z

c2600#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.


!-- Select FastEthernet 0/0 for the trunk configuration. !-- No L2 or Layer 3 (L3) configuration is done here.

c2600(config)#int fastEthernet 0/0
c2600(config-if)#no shut
c2600(config-if)#exit


!-- Enable trunking on the sub-interface FastEthernet 0/0.1. !-- Note that actual trunks are configured on the sub-interfaces.

c2600(config)#int fastEthernet 0/0.1


!-- Enter the trunking encapsulation as either isl 
c2600(config-subif)#encapsulation isl 1


!-- or as dot1q: !-- In case of dot1q, you need to make sure that !-- the native VLAN matches across the link. !-- On 3512XL, by default, the native VLAN is 1. !-- On the router, configure VLAN1 as the native VLAN.

c2600(config-subif)#encapsulation dot1Q 1 ?
  native  Make this is native vlan
  <cr>
c2600(config-subif)#encapsulation dot1Q 1 native

!-- On the switch, if you have a native VLAN other than VLAN1, !-- on the router, configure the same VLAN to be the native VLAN, !-- by using the above command.

注意： Cisco IOS 版本 12.1(3)T 中增加了 encapsulation dot1Q 1 native 命令。如果您使用的是更早的 Cisco IOS 版本，请参阅本文档的“版本低于 12.1(3)T 的 Cisco IOS 的 802.1Q 配置”部分，以便在路由器上配置 802.1Q 中继。

!-- Configure L3 information on the sub-interface 0/0.1.

c2600(config-subif)#ip address 10.10.10.1 255.255.255.0
c2600(config-subif)#exit


!-- Enable trunking on the sub-interface FastEthernet 0/0.2. !-- Note that actual trunks are configured on the sub-interfaces.

c2600(config)#int fastEthernet 0/0.2


!-- Enter the trunking encapsulation as either isl

c2600(config-subif)#encapsulation isl 2


!-- or as dot1q:

c2600(config-subif)#encapsulation dot1Q 2


!-- Configure L3 information on the sub-interface 0/0.2.

c2600(config-subif)#ip address 10.10.11.1 255.255.255.0
c2600(config-subif)#exit
c2600(config)#^Z


!-- Remember to save the configuration.

c2600#write memory
Building configuration...
[OK]
c2600#

注意： 为了使此设置生效并使工作站 1 和工作站 2 之间成功 ping 通，您需要确保工作站上的默认网关设置正确。工作站 1 的默认网关应该是 10.10.11.1，工作站 2 的默认网关应该是 10.10.10.1。有关如何设置工作站上的默认网关的详细信息，请参阅本文档中相应的部分。

注意： 只有当您在路由器和交换机之间配置了 802.1Q 中继时，以下段落才适用。

注意： 如果您按照上述部分列出的配置步骤操作还不能通过 VLAN ping 通工作站 1 和工作站 2，则您可能遇到了 Caveat CSCds42715，在发生该问题的情况下，当启用快速切换时，802.1Q 本地 VLAN 关键字无法正常工作。该 Bug 的修复程序集成到了下列代码版本中：12.2(0.5)、12.2(0.5)T、12.1(5)DC、12.1(5)YB、12.2(0.18)S、12.1(5)YD02、12.2(2)B、12.2(15)ZN。您可以通过使用 Bug 工具包（仅限注册用户）并输入 Bug ID CSCds42715 来检查该 Bug 的状况和简要描述。

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

c2600#show running-config
Building configuration...
 
Current configuration:
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname c2600
!
no logging console
enable password mysecret
!
!
!
!
!
ip subnet-zero
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
 no ip address
 duplex auto
 speed auto
!
interface FastEthernet0/0.1
 encapsulation isl 1
 ip address 10.10.10.1 255.255.255.0
 no ip redirects
!

!-- If 802.1Q is configured, !-- you will instead see the following output !-- under interface FastEthernet0/0.1: !-- interface FastEthernet0/0.1 !-- encapsulation dot1Q 1 native !-- ip address 10.10.10.1 255.255.255.0

!
!
interface FastEthernet0/0.2
 encapsulation isl 2
 ip address 10.10.11.1 255.255.255.0
 no ip redirects
!

!-- If 802.1Q is configured, !-- you will instead see the following output !-- under interface FastEthernet0/0.2: !-- interface FastEthernet0/0.2 !-- encapsulation dot1Q 2 !-- ip address 10.10.11.1 255.255.255.0

!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
ip classless
no ip http server
!
!
!
line con 0
 transport input none
line aux 0
line vty 0 4
 password mysecret
 login
!
no scheduler allocate
end

!-- Set the privileged mode !-- and Telnet password on the router.

Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#hostname c2600
c2600(config)#enable password mysecret
c2600(config)#line vty 0 4
c2600(config-line)#login;
c2600(config-line)#password mysecret
c2600(config-line)#exit
c2600(config)#no logging console
c2600(config)#^Z

c2600#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.


!-- Select FastEthernet 0/0 for the trunk configuration.

c2600(config)#int fastEthernet 0/0
c2600(config-if)#no shut


!-- Note that the IP address for VLAN1 is configured on the main interface, !-- and no encapsulation for VLAN1 will be done under the sub-interface.

c2600(config-if)#ip address 10.10.10.1 255.255.255.0
c2600(config-if)#exit


!-- Configure dot1q encapsulation for VLAN 2 !-- on sub-interface fastEthernet 0/0.2.

c2600(config)#int fastEthernet 0/0.2
c2600(config-subif)#encapsulation dot1Q 2
c2600(config-subif)#


!-- Configuring L3 information on the sub-interface 0/0.2.

c2600(config-subif)#ip address 10.10.11.1 255.255.255.0
c2600(config-subif)#exit
c2600(config)#^Z


!-- Remember to save the configuration.

c2600#write memory
Building configuration...
[OK]
c2600#

注意： 为了使此设置生效并使工作站 1 和工作站 2 之间成功 ping 通，您需要确保工作站上的默认网关设置正确。工作站 1 的默认网关应该是 10.10.11.1，工作站 2 的默认网关应该是 10.10.10.1。有关如何设置工作站上的默认网关的详细信息，请参阅本文档中相应的部分。

c2600#show running-config
Building configuration...

Current configuration:
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname c2600
!
no logging console
enable password mysecret
!
!
!
!
!
memory-size iomem 7
ip subnet-zero
!
!
!
!
!
!
!
interface FastEthernet0/0
 ip address 10.10.10.1 255.255.255.0
 duplex auto
 speed auto
!
interface FastEthernet0/0.2
 encapsulation dot1Q 2
 ip address 10.10.11.1 255.255.255.0
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
ip classless
no ip http server
!
!
line con 0
 transport input none
line aux 0
line vty 0 4
 password mysecret
 login
!
no scheduler allocate
end

c2600#