Question 9/VII - Principles of maintenance in user-network interfaces
for public data networks (continuation of Question 25/VII studied in
1985- 1988)

considering

(a) that public data networks utilizing Recommendations X.20, X.20bis,
X.21, X.21bis, X.22, X.25 and X.32 are being implemented;

(b) that Recommendations X.30 and X.31 define the Terminal Adaptor (TA)
functions to adapt circuit switched and packet switched X-Series DTE/DCE
interfaces to ISDN;

(c) that Recommendation X.150 defines the principles of maintenance
testing using DTE and DCE test loops and details of maintenance testing
using DTE and DCE test loops are described in the individual DTE/DCE
interface Recommendations;

(d) that Recommendation G.704 defines the maintenance mechanisms for
digital networks, I.600-Series Recommendations define ISDN subscriber
access and installation maintenance, and that Q.940-Series
Recommendations define ISDN user-network management interface;

(e) that the maintenance of public data networks are under the
responsibility of administrations and operating agencies, and that
maintenance principles must be harmonized in order to:

-provide, as far as possible, the same maintenance of customer services,

-define maintenance principles on international sections between two
public networks;

it is necessary to study the following:

1. What principles for fault locating and maintenance testing for PDN
DTE/DCE interfaces and TA defined by X.30 and X.31 are required in
addition to the existing ones?

2. What features must be harmonized to result in common management
services for subscribers?

3. What differentiation would be appropriate between each layer
management and system management at layer 7?

4. How can OSI management be used?

5. What management objects for PDN need to be defined based on common
management from work specified by Question 24/VII.

6. What other management aspects (e.g. accounting, configuration and
security control) in addition to maintenance should be studied?

Note 1 - Close cooperation with the relevant Questions in this Study
Group (OSI reference model and higher layer protocols) on OSI management
is expected.

Note 2 - Close cooperation with Study Groups regarding TA in ISDN is to
be established.

Note 3 - Close cooperation with Study Groups on telecommunication
management is to be established.