Question 3/XVIII - Network aspects of digital hierarchies

Considering

(a) that Recommendations G.702, G.707, G.708, G.709 and G.802 give
information concerning digital hierarchies;

(b) that transport of high capacity digital signals and that network
arrangements can be done in the future on the basis of synchronous
digital multiplexing techniques;

(c) that the concept of synchronous multiplexing and of a Synchronous
Digital Hierarchy should be transmission media independent;

(d) that broadband services may require transmission capacities in
excess of the capacity provided by the basic building block of the
Synchronous Digital Hierarchy (150 Mbit/s);

(e) that the concept of Synchronous Digital Hierarchy allows for easy
growth to higher bit rates in step with the evolution of transmission
technology;

(f) that Path Overhead (POH) and Section Overhead (SOH) associated with
Virtual Containers (VC) and with the Synchronous Transport Module (STM)
respectively provide the opportunity for enhanced OAM capabilities;

(g) that ATM techniques are being studied for broadband access to the
ISDN;

(h) that many new terms, not yet included in Recommendations G.701,
I.112 or I.113, are being used in Recommendations G.707, 708 and 709;

the following should be studied:

1. What higher levels (above STM-4) of the Synchronous Digital Hierarchy
should be recommended?

2. What multiplexing structures should be recommended for Broadband
Signals requiring STM-1 concatenation?

3. What are the amendments that may be required to Recommendations G.708
and G.709 to facilitate media independence, in particular with regard to
interfaces?

4. What are the implications on Recommendations G.708 and G.709 of
different applications of the Synchronous Digital Hierarchy concept (for
example, within station, short-haul, long-haul)?

5. What overhead specifications should be included in Recommendations
G.708 and G.709 to take advantage of enhanced OAM capabilities?

6. What mappings of source signals over and above those already
contained in Recommendation G.709 are required and how should they be
specified?

7. What provisions have to be made to allow for the transport of ATM
based signals?

8. What terms used in Recommendations G.707, 708, and 709 should be
included in the Recommendations G.701, I.112 or I.113 on terminology and
how should they be defined?

9. What revisions need to be made to Recommendations G.702, G.703, G.704
and G.706?

Note - To be studied in close liaison with Study Group XV.