The MPLS WG Archive

[neil.2.harrison@bt.com]

Alex Zinn wrote:
>I wouldn't oversimplify this [NH=> that is, against this statement from
Yangguang "In circuit switched network, there should be no assumption about
the relation of data plane topology and control plane topology at all."]
	Don't forget about IGPs and signaling.

Alex can you please expand on what you mean by this....taking the following
into account line of reasonong?

-	the OTN is cct-sw/CO/client-layer PDU-structure transparent
-	the OTN has no practical buffers
-	IP, ATM, FR, SDH, or whatever is irrelevant as far as the OTN
user-plane is concerned.
-	"server layer trails (in an OTN) = client layer links", and networks
operators *will* have to support multiple client layers for a very long
time...including some large BW servives directly off the L1 fabric.
-	above implies no congruent addressing between any pair of client
layers or any client layer and the OTN........this implies that the
addresing scheme used by the OTN is not related to any clients (ie not from
the same addressing space in terms of possible trail connectivity at layer
network access points)
-	it therefore follows (at least to many I speak to who are working on
OTN topics) that the signalling protocol and the routing/discovery protocol
used in the OTN can be chosen as 'best of breed' to suit its nature, ie
cct-sw/CO/user-plane transparent.  Obviously different people will have
different views of what is best-of-breed here.......and this has not to my
knowledge has not even been openly debated so far.
-	further, the signalling network of the OTN needs to be designed with
very high availability/survivability requirements.  To achieve this its
topology and operating mode are a completely independent facet to how the
user-plane is specified for the normal 'client traffic'.

regards, neil