DEFINITY ECS Release 8.2 Maintenance for R8.2csi
555-233-119 Issue 1
April 2000
Maintenance for csi systems
1-16Maintenance Testing
1
■Fixed interval tests are performed at reg ular time intervals that cannot be
administered. These tests run conc urrently with periodic mainten ance.
The following table lists the MOs that run fixed interval testing.
Demand tests are also run by the system when it d etects a need or b y
maintenance personnel in troub le-clearing activities. Using the management
terminal, maintenance personnel c an “demand” the same tests that the system
initiates in periodic or background test ing. Demand tests includ e periodic tes ts
plus other tests required only when troub le occurs. Some nonperiod ic demand
tests are destructive (service-disrupting) tests, and are identified in boldfac e
type.
Layers
The Open System Interconnect (OSI) model for dat a communications contains
seven layers, each with a spec ific function. Communic ations to and through the
system concern themselves only with layers 1 and 2 of the model.
Layer 1, or the

physical layer,

covers the physical interface between de vices and
the rules by which bits are p assed. Among the p hysical layer protoc ols are
RS-232, RS-449, X.21, DCP, DS1, and others.
Layer 2, or the

data-link layer

, refers to code created a nd interpreted by the D CE.
The originating equipment c an send blocks of data with the necessary c odes for
synchronization, error control, or flow c ontrol. With these codes, the destination
equipment chec ks the physical-link reliab ility, corrects any transmission errors,
and maintains the link. When a transmission reaches the d estination equipment,
it strips any layer-2 information the orig inating equip ment may have inserted. The
destination equipment only passes to the destination DTE equipm ent the
information sent by the originating DTE equipment. The originating DTE
equipment can also ad d layer-2 code to b e analyzed by the d estination DTE
equipment. The DCE equipment treats this layer as d ata and passes it along to
the destination DTE equipment as it would any other binary bits.
Layers 3 to 7 (and the DTE-created layer 2) are embed ded in the transmission
stream and are meaningful only at the d estination DTE equipment. Therefore,
they are shown in the figure as “user-defined ,” with no state chang es until the
transmission stream reaches its destinatio n.
Maintenance Object Interval (min)
POWER 60
SPE-SELEC 60
TDM-BU S 10
TONE-PT 10