The MPLS WG Archive

[Jeremy Lawrence <jlawrenc@cisco.com>]

Jim,

At 05:13 04/27/2000 -0400, Jim Sullivan wrote:
>Jeremy, 
>
>
>At 06:47 PM 04/26/2000 +1000, Jeremy Lawrence wrote:
> >At 17:39 04/25/2000 -0700, Bora Akyol wrote:

[...]
> >>FEC to LSP binding is almost historical now.
> >
> >That's arguably true in router-based networks, because of the
> >predominance of TE as an application of MPLS in those networks.
> >However, FEC to LSP binding is very much alive in ATM MPLS
> >networks. 
>I'm not sure I completely follow this thread. I make the assumption
>that Bora believes all packets that do not get forwarded on 
>TE LSPs can be efficiently forwarded as unlabeled packets. 
>Is the point your raising that ATM-LSRs in general can not
>be expected to forward unlabeled traffic efficiently ? 

Exactly right. ATM-LSRs do not necessarily have any capability
of forwarding unlabelled packets. Most, but not all, ATM-LSRs 
have some capacity to forward unlabelled packets, but (in all
cases I'm aware of) this is limited compared to their capacity
for labelled packet forwarding.

So, where the 'default' forwarding mechanism in a router network
using MPLS TE can sometimes be ordinary IP packet forwarding (see
also the next paragraph), the default mechanism in an ATM MPLS
network normally must be hop-by-hop routed MPLS.

There are also several VPN schemes that require labelled packet
forwarding as the default in any type of MPLS network over which
they operate.

Regards,

Jeremy Lawrence