The MPLS WG Archive

[Olle Pers <Olle.K.Pers@telia.se>]

*  
*  I would agree with you on this one.
* 
Well, here is one that would not agree, without more convincing arguments. 

  
*  Your second point is key.  How can you know that the 
*  destination address in the packet is an IGP prefix?  
*  I suspect that many networks will want to run BGP 
*  edge-to-edge, but to have only IGP routes in the core. 
*
The IGP knew the prefix, and B had sent out a label mapping 
for it. That was the scenario in David's question. 
So the router B knows how to forward unlabeled packets with this prefix. And
it did send out a label mapping for exactly the same prefix, knowing that it
didn't have any corresponding downstream label yet. Why? I don't want to
think B did that just in order to drop these packets.   


*  In addition to this you have the issue of MPLS VPN and Layer 
*  2 over MPLS traffic.  Either one of these will generate a 
*  label stack in which the innermost label is assigned edge-to-
*  edge and is not visible to the intermediate devices.
*  
These applications require that there exists an edge-to-edge LSP which can
be used as a tunnel. We cannot assume them to work, before the setup of this
LSP is completed. And with unordered control, the ingress will not know when
this has happened. 


But why use unordered control at all, if it leads to problems? What's the
application? 


* 
*  Giles
*  

Olle Pers
Telia, Sweden