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>ds
>ul
OPERATING AND MAINTENANCE SYSTEM FOR TELEPHONE EXCHANGES
>a1 INTRODUCTION
The objects of an operating and maintenance system (OMS system) is to
increase the depen_dabili_ty and limit any damage to the tele_communi_cation
system. This is attained by a con_tinous sur_veillan_ce of ope_rating
functions, so that a quick registering and remedying of faults will be
possible. Thus inconvenience to sub_scribers in case of faults and
inter_ruptions of opera_tion and operatio_nal expenses are reduced.
At the same time a better utili_zation of the equipment will be
achie_ved. In addition to this the OMS system should be able to have
controlling func_tions in the systems from a central place.

This paper will deal with only operation and maintenance of the
telecom_munica_tion systems.

A separate paper discusses the possi_bility of integra_tion of other
func_tions, such as fire and burglar alarm, and remote control
func_tions at the sub_scribers' location.

The following tasks are covered by the OMS system:

- surveillance of the operation of the tele_phone
exchan_ges and their inter-change routers.

- traffic measurement of inter-change routers.

- surveillance of the operation of subscriber routers. 

- alterations to data, e.g. category of subscriber and
routing tables.

- subscriber alarms (fire, burglary, etc.).

>ne 25
>sp 23
>fg Terminology in the telecommunication network

>a2 Surveillance of the Operation
The organs of a conventional tele_phone exchange, which have to be
considered, are:

 - inter-exchange routers
    
 - subscriber registers (REG-L/E)

By far the largest number of faults are found in the inter-exchange
routers, and of these approximately 80 % are due to the fact that
the routers cannot be engaged on account of a "technical fault".

As an example of the require_ments, which can reasonab_ly be made
to an operating sur_veillan_ce philosophy, the follo_wing may be
men_tioned:

>tb 3 1)
80 % of all fault reports should lead to the remedying of the fault.

>tb 3 2)
A fault should be recognized within a cer_tain time, depen_dent
on the traf_fic inter_ruption caused.

>tb 3 3) 
A fault should be able to be stated at organ level.

The first require_ment is made to ensure that the opera_ting
personnel can really rely on the system.

The second require_ment is made partly to en_sure that serious
faults are re_ported quickly enough, and partly to ensure that
un_necessary resour_ces are not used to find less serious faults.

>a2 Traffic Measurement on Inter-exchange Routers
Traffic measure_ments are used for control and for prog_noses
of the traf_fic interest.

>a3 Control
The object of the control is to ensure that the actual dimen_sio_ning
of the exchange and inter-change routers is appropriate.

The control will give the alarm, if organ groups are grossly over or
under dimensioned.

>a3 Prognosis of Traffic Interest
The object of the prog_nosis is to ensure that the quan_tities of
equip_ment and the chan_ging over requi_red by increa_sed traffic
will be availab_le at the required time.

The traffic interest can be measured either traditional_ly as
traffic ex_changes for each routing, coupled with a call analysis
on a spot test basis or by registering the traffic ex_chan_ges
for each number direction, inde_pendent of the physical feed
rou_ting.

>a2 Surveillance of the Operation of Subscriber Routers
Partly to ensure that the sub_scribers get a reasonable ser_vice
and partly to keep the operatio_nal expen_diture down at an 
accep_table level, it is contem_plated within Jutland Telephone
to connect locally placed measuring boxes to the OMS system. The
mea_suring boxes, which are to be placed in the indi_vidual 
exchan_ges, are primarily to make an insula_tion measure_ment
and secondari_ly an inter_ruption measurement. On the basis
of these two mea_suring methods, it is believed that it can be
stated with reasonable certainty whether it is a question of
a cable or installa_tion fault.

The measure_ments should partly be made at the request of e.g.
a OMS centre and partly automatically. The automatic test ensures
that a fault is normally reported so quickly that the remedying
of the fault can be arran_ged instead of making panic turn-outs
from one fault place to another.

>a2 Alteration of Data
In the case of new ex_changes or up_dated ex_changes, e.g. 
L.M. Ericsson's ANA-30 system, it is possible to alter the
cate_gories of indivi_dual sub_scribers, e.g. slot tele_phones,
exemption from payment of rates, and tele_phone answering
ser_vice. Depen_dent on the types of ex_change and/or the
degree of inter_vention made into existing ex_changes it will
be desirable, if certain types of data could be altered, e.g.:

 - category of subscriber
 - routing tables
 - tariffs

>a1 PROVIDING FOR THE FEATURE
In connec_tion with the struc_turing of a compre_hensi_ve OMS system
it should be ensured that the new exchange types can be inte_grated
into the system. This applies not only to the inter_face between
OMS system and ex_change, but also between OMS and user, so that
the same lan_guage of command (MML re_commend by CCITT) and
wor_king method may be used, irrespec_tive for the ex_change
type used for commu_nication.

>a1 SYSTEM OUTLINE
On the basis of ex_perien_ce gained by tests at Jutland Telephone
the struc_ture of the actual data net_work will depend on what
is most appro_priate in the actual places. Jutland Tele_phone
is con_templa_ting the in_sertion of a number of con_cen_tra_tors
between the OMS centres and the terminal stations (TS), so that
the configu_ration will appear as in fig. 3.


>ne 40
>sp 
>fg Proposal for OMS system structure

>ne 40
>sp 38
>fg Proposal for OMS data network structure

>ul
The terminal stations
(TS) consti_tute the inter_face to the tele_phony equip_ment
or the equip_ment wat_ching it. This means that the con_trol
and sur_veillan_ce func_tions can either be placed in TS or
be placed out_side, so that it is a pure data net_work, to which
various ex_ternal units are con_nected. The solu_tion chosen will
partly depend on the func_tions to be assigned to the OMS system,
and partly on the other tasks which may use the same data net_work
see fig. 4

>ne 40
>sp 38
>fg Appplic. of a general data network by OMS system

The OMS centre should be able to take a com_pre_hen_sive
view of its part of the tele_communi_cation systems. Whether the
OMS centre should be the starter in rela_tion to the local personnal
will depend on the actual organi_zation. However, it should
be ensured that the OMS system does not bind the tele_phone
compa_ny unnecessa_ry with regard to being able to freely choose
the currently most suitable organization.

In the OMS centre there should be a rea_sonable large cal_culating
and storing capa_city for dealing with traffic measurements, other
statistical materials, and possible also the de_biting of calls.
Further, the OMS centre should inclu_de routing tables for the
various alarm types. These routing tables may be trans_ferred
to data networks and terminal stations from the OMS centre.
«eof»