RE: Switching technologies requiring bidirectional asymmetric LSPs?

["Don Fedyk" <dwfedyk@nortel.com>]

Hi Adrian

Lou stated: 
> > Please keep in mind that service requirements are not the 
> > same thing as switching technology requirements.  For 
> > example, we have long built  bidirectional asymmetric 
> > services on unidirectional MPLS LSPs.
> 
And Adrian asked: 
> Well, exactly!
> Perhaps someone can explain why the Ethernet hardware is 
> forced to require bidirectional asymmetric LSPs when MPLS 
> is happy without?

A clarification. I assume you are asking why Ethernet hardware is
bidirectional?  Hardware is agnostic to the asymmetric BW aspects above
as far as I know. 

Why bidirectional? In the case of Ethernet, Ethernet Bridging Hardware
uses Bidirectional Relays, symmetric spanning trees and optionally
learning (learning requires symmetry and is built into the relay
function). 

We could debate the origins of this etc. But that is not what we are
chartered to do. We should not be asking "How do we change the
technology to fit GMPLS?".    

Regards,
Don