[f-nsp] Double tagging over VPLS in MLXs

[Eric Helm]

On 6/24/2010 1:42 PM, Grady Neely wrote:
> Hi,
> 
> I would like to send many Q-in-Q VLANS across a VPLS instance.  I really do not care what the tags are, I essentially want a transparent service, that preserves the same tags from ingress on the egress ports of the VPLS instance.
> 
> What is the best way to do this?  
> 
> Should I set the tag-type on the VPLS instance to 9100 (the CE traffic is using 8100 for both tags) and set the port to untagged in the VPLS?  
> 
> Is this how to carry multiple VLANS across implicitly in a MLX?  
> 
> Does this work for double and single tagged traffic?  
> 
> What about untagged traffic?  
> 
> What should the VC mode be set to, raw or tagged?
> 
> Thank you!
> 

I'd use 88A8 as the tag-type per 802.1ad and MEF standards.

Here is a config that works for me:

tag-type 88a8 ethe 3/18

router mpls
  vpls Q-in-Q 100
  vpls-mtu 2000
  vlan 100
   untagged ethe 3/18

This allows for proper Q-in-Q with the default VC mode of raw.
In my case raw mode seems to fit fine, but I'm not too clear on when to
use tagged mode.

Perhaps someone can explain better when to use tagged mode vs. raw mode.

/Eric