363-206-305
Applications
2-10
Issue 3 June 2000
Single-Homed Access via Backbone Ring
2
Figure 2-4 and Figure 2-5 illustrate how single-homed OC-1 extensions can
satisfy a growing access network. Single-homing applications connect both
rotations of the OC-1 extension to a single DDM-2000 OC-3 Multiplexer or
SLC
-
2000 Access System host. The DDM-2000 FiberReach is placed at the
customer's location, such as in a telecommunications equipment closet on each
floor of a high-rise office complex, and delivers protected DS1 channels to the
business customer.
The OC-1 ring capability allows multiple DDM-2000 FiberReach systems to be
connected to the backbone network via a single facility. Compared to other optical
extension products that are limited to a single remote node per extension, the
ring-based DDM-2000 FiberReach solution uses far less fiber and host optics for
typical serving areas with multiple business locations. Network growth is as easy
as adding another DDM-2000 FiberReach node on the ring; no additional fiber or
host circuit packs are required.
With the dual OC-1 capability of the 27G-U optical line interface unit (OLIU), a
DDM-2000 OC-3 ring node supports up to six single-homed OC-1 extensions; a
SLC
-2000 Access System access resource module (ARM) shelf can supply up to
two single-homed OC-1 extensions. Thus, competing businesses in the same
serving area can receive a dedicated access facility into the backbone ring,
alleviating any privacy concerns.
The DDM-2000 FiberReach remote system employs standard path protection
switching for a highly reliable network that guarantees 60 millisecond recovery
from any single facility or equipment failure. Path protection switching occurs at a
node in which the channel is dropped from the ring to a low-speed interface. For
example, in Figure 2-4 the remote DDM-2000 FiberReach nodes and the DDM-
2000 OC-3 in the wire center supply the path switching function for a survivable
end-to-end transport between the customer and wire center. Channels pass
between the OC-1 and OC-3 rings at the host DDM-2000 OC-3 and
SLC
-2000
systems with a ring (0x1) low-speed interface. This arrangement supports full TSI
assignment between low-speed and high-speed time slots while preserving
independent service and protection paths between the host and extension rings.
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