From: Brian McGahan (brian@mcgahan.com)
Date: Sat Jul 26 2003 - 18:26:04 GMT-3
Richard,
By default, all VLANs are allowed to transit a trunk link. They
are considered to be in the 'allowed list' for that trunk.
Switch#sh int fa0/13 trunk | begin allowed
Port Vlans allowed on trunk
Fa0/13 1-4094
Switch#sh int fa0/13 switchport | in Trunking VLANs Enabled
Trunking VLANs Enabled: ALL
As you can see from the above output, port fa0/13 is trunking,
and all vlans from 1-4094 are allowed to transit it. In order to change
what is in the allowed list, use the interface command 'switchport trunk
allowed vlan'.
Switch(config-if)#switchport trunk allowed vlan 100
Command rejected: Bad VLAN allowed list.
VLANs 1002-1005 are required.
As you can see from this output, the 3550 requires that
1002-1005 remain on the trunk link.
Switch(config-if)#switchport trunk allowed vlan 100,1002-1005
Switch#sh int fa0/13 switchport | in Trunking VLANs Enabled
Trunking VLANs Enabled: 100,1002-1005
Switch#sh int fa0/13 trunk | begin allowed
Port Vlans allowed on trunk
Fa0/13 100,1002-1005
Now the only VLANs that will transit this interface are 100, and
1002 through 1005.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Richard L. Pickard
> Sent: Saturday, July 26, 2003 4:18 PM
> To: Ccielab@Groupstudy. Com
> Subject: only allow one VLAN across trunk on 3550
>
> Fiesta===
>
>
> I am working a lab that asks you to configure ISL trunk between two
3550's
> &
> only allow VLAN 504
>
> I created the trunk & created some VLAN's (including VLAN 504) on the
VTP
> master.
>
> Can anyone tell me how to allow only VLAN 504 thru the trunk ?
>
>
>
> interface GigabitEthernet0/1
>
> switchport trunk encapsulation isl
>
> switchport mode trunk
>
> [GroupStudy removed an attachment of type image/jpeg which had a name
of
> Fiesta Bkgrd.jpg]
>
>
>
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