Re: IXP

[Nathan Ward <nanog () daork net>]

On 18/04/2009, at 12:08 PM, Paul Vixie wrote:
> i should answer something said earlier: yes there's only 14 bits of  
> tag and
> yes 2**14 is 4096.  in the sparsest and most wasteful allocation  
> scheme,
> tags would be assigned 7:7 so there'd be a max of 64 peers.  it's more
> likely that tags would be assigned by increment, but it's still  
> nowhere
> near enough for 300+ peers.  however, well before 300 peers, there'd  
> be
> enough staff and enough money to use something other than a switch  
> in the
> middle, so that the "tagspace" would be per-port rather than global  
> to the
> IXP.  Q in Q is not how i'd build this... cisco and juniper both have
> hardware tunnelling capabilities that support this stuff...  it just  
> means
> as the IXP fabric grows it has to become router-based.


On Alcatel-Lucent 7x50 gear, VLAN IDs are only relevant to that local  
port. If you want to build a "VLAN" that operates like it does on a  
Cisco switch or something, you set up a tag on each port, and join the  
tags together with a L2 switching service. The tag IDs can be  
different on each port, or the same... it has no impact.

--
Nathan Ward