[Xorp-hackers] Doubt on VLAN implementation

[Bruce M Simpson]

Pavlin Radoslavov wrote:
> I have to admit that when comes to VLANs I am thinking the IEEE
> 802.1Q Standard.
> How the relationships you describe above fit with 802.1Q?
> If you have an URL with detailed description that would be useful.
>   

There are folk out there using multiple 802.1Q encapsulation headers, 
particularly for stuff like Metro Ethernet. It is sometimes called "Q-in-Q".

The encapsulation thing was a requirement crunch when rethinking the 
FreeBSD ether_input() path this time last year -- and all I wanted to do 
was make 802.1p work with my VoIP ATA...

I didn't see any reason to support more than 2 levels of encapsulation 
on the same link layer, however it's entirely possible people are doing 
more than 2.

Having said that, I'd like to see how Q-in-Q is configured on vendor 
equipment before making any radical changes anywhere. For XORP, 
personally I prefer the interface foo0 { vif vlan10 { ... }  } style 
syntax, but how to capture Q-in-Q in that syntax is an open question.

cheers
BMS