[c-nsp] Blocking vlan 1 on trunked ports?

[robbie]

Brett Looney wrote:
> At 05:41 15/07/2005, you wrote:
> 
>>Why can you not remove vlan 1 ? Technical or Political Issue ?
> 
> 
> I know that you can't remove VLAN 1 from trunks on the 3550 but you can on 
> the 3750...
> 
> So, on the 3550 the best way is to make another VLAN the native VLAN on 
> that trunk...
> 


Rack1SW1>en
Rack1SW1#config t
Enter configuration commands, one per line.  End with CNTL/Z.
Rack1SW1(config)#int f0/1
Rack1SW1(config-if)#switchport encaps dot1q
Rack1SW1(config-if)#switch mode trunk
Rack1SW1(config-if)#switch trunk allowed vlan remove 1
Rack1SW1(config-if)#do show ver
Cisco Internetwork Operating System Software
IOS (tm) C3550 Software (C3550-I5K2L2Q3-M), Version 12.1(19)EA1c, 
RELEASE SOFTWARE (fc2)
Copyright (c) 1986-2004 by cisco Systems, Inc.
Compiled Tue 03-Feb-04 10:39 by yenanh
Image text-base: 0x00003000, data-base: 0x009428D4

ROM: Bootstrap program is C3550 boot loader

Rack1SW1 uptime is 48 minutes
System returned to ROM by power-on
System image file is 
"flash:c3550-i5k2l2q3-mz.121-19.EA1c/c3550-i5k2l2q3-mz.121-19.EA1c.bin"

...(pruning on show ver enabled)...

Rack1SW1(config-if)#do show int f0/1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Fa0/1       on           802.1q         trunking      1

Port      Vlans allowed on trunk
Fa0/1       2-4094

Port        Vlans allowed and active in management domain
Fa0/1       2-4,12,16,36,43,45,258

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/1       2-4,12,16,36,43,45,258
Rack1SW1(config-if)#switchport native vlan 4094
Rack1SW1(config-if)#do show int f0/1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Fa0/1       on           802.1q         trunking      4094

Port      Vlans allowed on trunk
Fa0/1       2-4094

Port        Vlans allowed and active in management domain
Fa0/1       2-4,12,16,36,43,45,258

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/1       2-4,12,16,36,43,45,258
Rack1SW1(config-if)#


Yes, you can unequivocally remove VLAN1 from a trunk on a 3550. Unless 
I've just completely missed something.

Cheers,
Robbie