[c-nsp] Cat6500 VLAN cannot be assigned to a routed port sub-if?

[Patrick M. Hausen]

Good morning,

> Am 19.09.2016 um 09:52 schrieb Peter Rathlev <peter at rathlev.dk>:
> 
> On Sat, 2016-09-17 at 14:24 +0200, Łukasz Bromirski wrote:
>>> On 16 Sep 2016, at 17:32, Nick Cutting wrote:
>>> Depends on supervisor - With sup 2t - you could reuse vlans on
>>> subinterfaces, here is 2 subinterfaces on different ports, and an
>>> SVI all on vlan 281
>>> 
>>> !
>>> interface Vlan281
>>> no ip address
>>> shutdown
>>> end
>>> !
>>> interface TenGigabitEthernet2/5/9.281
>>> encapsulation dot1Q 281
>>> end
>>> !
>>> interface TenGigabitEthernet2/5/8.281
>>> encapsulation dot1Q 281
>>> end
>>  
>> That’s actually config that will work with all Supervisors, wrong
>> example :)
> 
> Nick is right, the config he showed would not work on Sup720 or
> earlier. And it wouldn't matter if VTP was enabled or not. If the VLAN
> exists "switched" then the first "encapsulation dot1q" command will be
> rejected with "Command rejected: VLAN <N> already in use by interface
> Vlan<N>". Trying to create more than two subinterfaces using the same
> VLAN (on different interfaces of course) is rejected with "Command
> rejected: VLAN <N> not available".

Correct. My problem is that I have a new peering partner and his VLANs
are already in use on my side. On the "toy" platforms like 1812 or a FreeBSD
or Linux host it's straightforward to just create a subinterface with the appropriate
tags attached to the packets. So I thought I could do the same on my Cat6500.

I just found out about VLAN mapping:
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/vlans.html#wp1044990

This *would* do the trick for me, if it wasn't for the fact that the mapping
is applied to all 12 ports in a port group. And since the VLAN is in use there
are of course ports where I don't want to map it ...

*argh* Can't they implement a single advanced feature in an unsurprising manner?

Thanks for all your help
Patrick
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