Lucent Technologies DDM-2000 OC-3, Руководство по установке

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6-16 Issue 9 October 1998
363-206-204
Release 7 Installation Tests
services and EC-1 interfaces are provided and thus VT and STS-1 cross-connects
are applicable.
Due to the flexibility and complexity of cross-connect s it is strongly recommended
to document the cross-connects of each site and have a compilation located at
each site. Therefore in the event the cross-connect map is lost, cross-connects
can be reestablished expeditiously.
Explanation of cross-connects
For DS1 service one can imagine 84 race tracks (timeslots/channels) around the
ring. Travel (transmission) takes place in both directions (receiving end chooses
best signal). Each track requires two "drop cross-connects" to enter/exit the track.
All other points on the ring require a "pass-through" cross-connect.
Release 7 software is a two fiber path-switched ring. Each VT or STS-1 (DS1 or
DS3 signal) is transmitted in both directions (clockwise and counterclockwise)
around the ring. The receiver monitors the signal from both directions and selects
the "best" one. This receiver will select the signal from the incoming fiber on OLIU
M1 as a default. The capacity of the ring is limited to the OC-3 line rate, which is
84 DS1 services or 3 STS-1‘s or a combination of the two. A timeslot or channel
must be reserved all the way around the ring for each service.
Drop cross-connects are designated by a ring VT/STS-1 channel and an
associated DS1/DS3/EC-1 port. Pass-through cross-connects are designated by
using the same ring VT/STS twice. See Figure 6-3.
In Release 7 drop cross-connects are divided into two types.
■
The standard twoway cross-connect, in which the ring VT/STS-1 channel is
connected to the associated DS1/DS3/EC-1 port of the node.
■
The drop and continue cross-connect, in which a VT/STS-1 signal is cross-
connected into an EC-1 port on a "drop and continue" node. At the same
time that this cross-connect is made, a second cross-connect is made that
continues a copy of that VT/STS-1 signal, on the same timeslot of the ring
that it came into this node on, transmitting it to the next node downstream
on the ring.
NOTE
:
A BBG6 (STS-1E) circuit pack is required in the function unit slots to make
a drop and continue cross-connect.
NOTE
:
The "drop and continue" nodes on a ring system must be setup in pairs,
otherwise there will be a loss of service when the ring path is switched.