Nortel Networks 3500 ユーザーズマニュアル
2-148 Operation, administration, and maintenance (OAM) features
OPTera Metro 3500 Multiservice Platform NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004
Tributary line timing
Tributary line timing is shown in
, example d).
When using tributary line timing, a network element derives timing from a
received tributary signal. Possible sources of tributary line timing are OC-3,
OC-12, OC-48, DS1, and EC-1 facilities.
received tributary signal. Possible sources of tributary line timing are OC-3,
OC-12, OC-48, DS1, and EC-1 facilities.
Note 1: Tributary line timing is derived from DS1 circuit pack
(NTN430AA, BA) provisioned in OPTera Metro 3500 shelf equipped with
VTX-series circuit packs. DS1 lining timing is not derived from the DSM
modules.
(NTN430AA, BA) provisioned in OPTera Metro 3500 shelf equipped with
VTX-series circuit packs. DS1 lining timing is not derived from the DSM
modules.
Note 2: Tributary line timing is derived from EC-1x3 (NTN436AA)
circuit pack.
circuit pack.
When the network element timing mode is set to Line Timing (no distinction
is made between Transport or Tributary on the user interface), it selects one of
up to two provisioned timing sources (primary and secondary timing
references) as the active timing reference. This signal is used in network
elements to synchronize the outgoing transport signals in all directions, and the
synchronous tributaries terminated by the network element. The selection of
the best quality signal is made based on the stability of the transport signal, the
synchronization message, and any incoming synchronization status
provisioned by the user. For more information on synchronization messaging,
see
is made between Transport or Tributary on the user interface), it selects one of
up to two provisioned timing sources (primary and secondary timing
references) as the active timing reference. This signal is used in network
elements to synchronize the outgoing transport signals in all directions, and the
synchronous tributaries terminated by the network element. The selection of
the best quality signal is made based on the stability of the transport signal, the
synchronization message, and any incoming synchronization status
provisioned by the user. For more information on synchronization messaging,
see
.
Table 2-30
Timing signal sources
Timing signal sources
Internal timing mode
VTX-48, VTX-48e or STX-192 circuit
pack
pack
provide timing signals of ST3 quality
External timing mode
BITS In A
BITS In B
building-integrated timing supply (BITS)
provide a clock of ST3 quality or better
provide a clock of ST3 quality or better
Line timing mode (transport / tributary)
OC-3
slots 3 through 10
OC-3x4
slots 3 through 10
OC-12
slots 3 through 12
OC-12x4 STS
slots 3 through 10 (see Note
OC-48
OC-48 STS
slots 3 through 12 (see Note
OC-192