Re: 802.1q tagging/untagging on Catalyst 2950

Your problem is the 'vtp mode transparent'. The vlans you created on this
switch will only be available on this switch. You will need to configure
'vtp mode server' in order to create vlans for use on other switches. Also
just for general reference VLAN1 is always present and DOT1Q encapsulation
does not tag frames on VLAN1 by default. Encapsulation is a confusing term
here as 802.1Q tags frames and Cisco's ISL encapsulates the frame.

HTH


"arthur" <arthurpaulh@xxxxxxxxx> wrote in message
news:1137688991.777987.154860@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> We have some problems using our Catalyst 2950 switches, problems that
> may be generated by an incomplete VLAN configuration: If we configure a
> trunk port, all the frames the switch sends on that trunk have no VLAN
> tag, no matter what VLAN they are coming from.
> It is possible to change the configuration, to obtain properly tagged
> frames (if the configuration is the problem)?
>
> Thanks in advance for any information.
>
>
>
> This is the configuration (partial):
>
> vtp mode transparent
> !
> spanning-tree mode pvst
> no spanning-tree optimize bpdu transmission
> spanning-tree extend system-id
> vlan 12-14
> !
> interface FastEthernet0/5
> !
> interface FastEthernet0/6
> switchport mode trunk
> switchport nonegotiate
> !
> interface Vlan1
> ip address 192.168.101.102 255.255.255.0
> no ip route-cache
>
>
> the result of show interface fa0/6 switchport:
> #sh interface fa0/6 switchport
> Name: Fa0/6
> Switchport: Enabled
> Administrative Mode: trunk
> Operational Mode: trunk
> Administrative Trunking Encapsulation: dot1q
> Operational Trunking Encapsulation: dot1q
> Negotiation of Trunking: Off
> 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
>
> the result of show interface fa0/6 trunk:
> #sh interface fa0/6 trunk
>
> Port Mode Encapsulation Status Native vlan
> Fa0/6 on 802.1q trunking 1
>
> Port Vlans allowed on trunk
> Fa0/6 1-4094
>
> Port Vlans allowed and active in management domain
> Fa0/6 1,12-14
>
> Port Vlans in spanning tree forwarding state and not pruned
> Fa0/6 1,12-14
>


.

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