RE: CE-to-CE PWs, Hierarchical VPLS and Pseudowire Stitching Function in draft-stein-pwe3-pwce2e-00.txt

["Yaakov Stein" <[e-mail]>]

[[Sasha]] I do not see this as ever becoming a standard approach.  PW labels
must be understood by the devices that terminate the pWs (in your case -
CE-2 and CE-3).These devices can have their own preferences regarding global
label space etc., and your "structured" labels can easily contradict these
preferences. Not every device is ready to receive and process any value
between 16 and 1M as a valid incoming labels (in fact, most don't). In
addition, you require the labels to be correctly interpreted in two points -
by the CE that terminates them and by the PE that adds transport labels
based on the PW ones. IMO, this is a fundamental contadiction with the MPLS
architecture and hence not acceptable. But let's, at least, present the
complete solution ("structured" non-local labels and all) and discuss it!
The draft did not ever mention "structured" labels (unless I missed
something), and I did not consider an option that clearly contradicts the
basics of the MPLS architecture.

[Y(J)S] But these are NOT MPLS labels, they are PW labels.
Why should PW labels be required to conform to the full MPLS
constraints?

[Y(J)S] What do we really need the PW label for? To diifferentiate
between multiple PWs going together in a tunnel between the same two devices.
For example, several E1s going between two points.
A very common solution is to use some coding of the port numbers
of these E1s.


<snip>


[[Sasha]] Franly I do not see it as a problem, but, if it is, let's solve it
in the specific devices that encounter it - this is definitely not a common
problem! 

[Y(J)S] Once again, the inner label is not a true MPLS label,
and I don't see the need to force it to be one.

Y(J)S