Specifications

Cisco ONS 15454 Product Overview
Network Configuration
38
Cisco ONS 15454 Product Overview, R3.3
May 2002
Network Configuration
The ONS 15454 supports unidirectional path switched rings (UPSRs),
bidirectional line switched rings (BLSRs), subtending rings, linear add-drop
multiplexer (ADM) supporting 1+1 protection, and mixed configurations. You can
also create path-protected mesh networks (PPMNs).
Unidirectional Path Switched Ring
The default protection scheme for an ONS 15454 is the UPSR. A UPSR is a
closed-loop, two-fiber transport architecture that survives cable cuts and
equipment failure because it provides duplicate fiber paths for each service.
Nodes in the ring are connected using a single pair of optical fibers. Working
traffic flows in one direction on the ring and the second fiber provides a protection
path flowing in the opposite direction. If a problem occurs in the working traffic
path, the receiving node switches to the path coming from the opposite direction.
Services can originate and terminate on the same UPSR or can be passed to an
adjacent access or interoffice ring for transport to the service-terminating
location. Because each traffic path is transported around the entire ring, UPSRs
are best suited for networks where traffic concentrates in one or two locations and
is not widely distributed.