From: Vazman@aol.com
Date: Thu Dec 30 2004 - 03:18:57 GMT-3
Need some clarification on this setup.
R1(E0/0)--trunk--(F0/1)3550Switch(F0/2)--trunk---(E0/0)R2
This is the config I have -
R1
interface Ethernet0/0
no ip address
half-duplex
!
interface Ethernet0/0.100
encapsulation dot1Q 100
ip address 192.168.100.1 255.255.255.0
!
interface Ethernet0/0.200
encapsulation dot1Q 200
ip address 192.168.200.1 255.255.255.0
R2
interface Ethernet0/0
no ip address
half-duplex
!
interface Ethernet0/0.100
encapsulation dot1Q 100
ip address 192.168.100.2 255.255.255.0
!
interface Ethernet0/0.200
encapsulation dot1Q 200
ip address 192.168.200.2 255.255.255.0
Switch
Cat3550A#sh run int f0/1
Building configuration...
Current configuration : 94 bytes
!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
end
Cat3550A#sh run int f0/2
Building configuration...
Current configuration : 94 bytes
!
interface FastEthernet0/2
switchport trunk encapsulation dot1q
switchport mode trunk
end
Cat3550A#sh int trunk
Port Mode Encapsulation Status Native vlan
Fa0/1 on 802.1q trunking 1
Fa0/2 on 802.1q trunking 1
Fa0/14 desirable n-isl trunking 1
Fa0/15 desirable n-isl trunking 1
Gi0/1 desirable n-isl trunking 1
Port Vlans allowed on trunk
Fa0/1 1-4094
Fa0/2 1-4094
Fa0/14 1-4094
Fa0/15 1-4094
Gi0/1 1-4094
Port Vlans allowed and active in management domain
Fa0/1 1,100,200
Fa0/2 1,100,200
Fa0/14 1,100,200
Fa0/15 1,100,200
Gi0/1 1,100,200
Port Vlans in spanning tree forwarding state and not pruned
Port Vlans in spanning tree forwarding state and not pruned
Fa0/1 1,100,200
Fa0/2 1,100,200
Fa0/14 1,100,200
Fa0/15 1,100,200
Gi0/1 1,100,200
Cat3550A#
With this config, I have connectivity between both routers on both VLAN's. Question is on the switch, the native vlan is 1 for both trunks but on the routers I have not defined a native vlan. Is 1 the default on the routers also?
Secondly, I tried changing the native VLAN to 100 by using the config below and I only have connectivity on VLAN 200. Any ideas? Did I configure something incorrectly? Thanks.
R1
interface Ethernet0/0
no ip address
half-duplex
!
interface Ethernet0/0.100
encapsulation dot1Q 100 native
ip address 192.168.100.1 255.255.255.0
!
interface Ethernet0/0.200
encapsulation dot1Q 200
ip address 192.168.200.1 255.255.255.0
R2
interface Ethernet0/0
no ip address
half-duplex
!
interface Ethernet0/0.100
encapsulation dot1Q 100 native
ip address 192.168.100.2 255.255.255.0
!
interface Ethernet0/0.200
encapsulation dot1Q 200
ip address 192.168.200.2 255.255.255.0
Switch
Cat3550A#sh run int f0/1
Building configuration...
Current configuration : 128 bytes
!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport mode trunk
end
Cat3550A#sh run int f0/2
Building configuration...
Current configuration : 128 bytes
!
interface FastEthernet0/2
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport mode trunk
end
Cat3550A#sh int trunk
Port Mode Encapsulation Status Native vlan
Fa0/1 on 802.1q trunking 100
Fa0/2 on 802.1q trunking 100
Fa0/14 desirable n-isl trunking 1
Fa0/15 desirable n-isl trunking 1
Gi0/1 desirable n-isl trunking 1
Port Vlans allowed on trunk
Fa0/1 1-4094
Fa0/2 1-4094
Fa0/14 1-4094
Fa0/15 1-4094
Gi0/1 1-4094
Port Vlans allowed and active in management domain
Fa0/1 1,100,200
Fa0/2 1,100,200
Fa0/14 1,100,200
Fa0/15 1,100,200
Gi0/1 1,100,200
Port Vlans in spanning tree forwarding state and not pruned
Port Vlans in spanning tree forwarding state and not pruned
Fa0/1 1,100,200
Fa0/2 1,100,200
Fa0/14 1,100,200
Fa0/15 1,100,200
Gi0/1 1,100,200
Cat3550A#
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