Question 4/XVIII - Network application of Synchronous Digital Hierarchy
with reference to the Network Node Interface (NNI)

Considering

(a) that Recommendations G.707, G.708 and G.709 specify the details of a
new Synchronous Digital Hierarchy;

(b) that the technology of the new Synchronous Digital Hierarchy permits
flexible rearrangements of channels and convenient insertion or removal
of channels of varying bandwidth at various points of a network;

(c) that a comprehensive overhead capacity provided in the new
Synchronous Digital Hierarchy facilitates improved provisioning,
maintenance and administration methods as well as rapid restoral of
network links that have failed;

(d) that some administrations will be introducing the new Synchronous
Digital Hierarchy into their existing networks as well as establishing
entirely new synchronous networks;

the following should be studied:

1. How should the new Synchronous Digital Hierarchy be utilized in
existing digital networks to benefit from the advanced capabilities?

2. What are the general principles for establishing new advanced digital
networks using the new Synchronous Digital Hierarchy which will provide
for efficient growth and capacity for new services including broadband
ISDN?