Use of Vlan 1002 - 1005

[ssieger]

Hi,

i've heard that it is now possible to use Vlan 1002 -1005, perhaps only on certain devices. Can anyone confirm this, or has even heard of ?

Thanks,

Stephan

[Peter Paluch]

Hello Stephan,

This is true on most, if not all, Cisco Catalyst platforms. You surely know this show vlan output:

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, Fa0/2, Fa0/3, Fa0/4
                                                Fa0/5, Fa0/6, Fa0/7, Fa0/8
                                                Fa0/9, Fa0/10, Fa0/11, Fa0/12
                                                Fa0/13, Fa0/14, Fa0/15, Fa0/16
                                                Fa0/17, Fa0/18, Fa0/19, Fa0/20
                                                Fa0/21, Fa0/22, Fa0/23, Fa0/24
                                                Gi0/1, Gi0/2
1002 fddi-default                     act/unsup 
1003 token-ring-default               act/unsup 
1004 fddinet-default                  act/unsup 
1005 trnet-default                    act/unsup 

Note that VLANs 1002 - 1005 are displayed as "unsup" - unsupported. These VLANs were originally intended for bridging with FDDI an Token Ring networks but as these data link layer technologies are not in use anymore, these VLANs are unused. However, because of backward compatibility reasons in IOS and VTP, these VLAN numbers remain reserved and can not be used.

Best regards,

Peter

[ssieger]

Hi Peter,

thanks for your fast response. It is, therefore everything remained as it was? There ist no need to use this vlans, but i   thought I would have read in a Ctalyst 6500 release note.

Regards,

Stephan

[Peter Paluch · Accepted solution]

Hello Stephan,

The output I posted above was captured on a Cat3560 running 15.0(1)SE IOS, one of the most recent versions. The VLANs 1002-1005 are still "unsupported", and I believe Cisco will continue leaving them that way for a long time yet.

Backward compatibility is sometimes a huge burden...

Best regards,

Peter