The architecture used in SONET technology. SONET rings, known as "self-healing rings," use two or more transmission paths between network nodes, which are typically digital cross-connects (DCSs) or add/drop multiplexers (ADMs). If there is a break in one line, the other may still be available, providing the second is not in close proximity to the first and also damaged. For the best security against failure, when possible, different physical routes are used for the two lines. The most fault-tolerant architecture is the four-fiber bi-directional ring. See SONET.
Two Fiber Unidirectional
This is the simplest SONET ring topology. All data are transmitted on the working or active path, while the standby path (protection path) lies in waiting. When a failure in the active path occurs, the two network nodes affected immediately switch to the standby line. Four fibers may used in a unidirectional system, but it is not usually done.
Two Fiber Bidirectional
In this architecture, traffic flows in both directions, but half the capacity of the line is used as a data channel and the other half for protection. In the event of failure, the alternate line takes up the slack.
Four Fiber Bidirectional
This is the most robust architecture which can withstand multiple failures providing the lines are routed in different locations. Both active and standby paths are duplicated in this topology, which is common in large carrier networks that cannot afford a breakdown.
Two Fiber Unidirectional
This is the simplest SONET ring topology. All data are transmitted on the working or active path, while the standby path (protection path) lies in waiting. When a failure in the active path occurs, the two network nodes affected immediately switch to the standby line. Four fibers may used in a unidirectional system, but it is not usually done.
Two Fiber Bidirectional
In this architecture, traffic flows in both directions, but half the capacity of the line is used as a data channel and the other half for protection. In the event of failure, the alternate line takes up the slack.
Four Fiber Bidirectional
This is the most robust architecture which can withstand multiple failures providing the lines are routed in different locations. Both active and standby paths are duplicated in this topology, which is common in large carrier networks that cannot afford a breakdown.
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2009 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- ONS-TDM-SONET - Optical Network Systems Time Division Multiplexing SONET v8.5
- View Available Dates and LocationsIn this lab-intensive course, you will get an introduction to the Cisco Optical Network System ONS Time Division Multiplexing TDM family of transport products. The ONS 15454, ONS 15310-MA, and ONS 15310-CL are SONET transport system components that can be mixed and matched to create high-speed...
- Training 2009-02-01
- Migration to Ethernet Rings: High Capacity, High Availability Mobile Backhaul Aggregation Transport
- This paper provides guidelines for mobile operators who wish to deliver higher capacities over their aggregation wireless backhaul networks. The paper will show how wireless Ethernet Ring topologies facilitate much better availability than typical SONET/SDH and how cost-per-bit reduction and improved overall user experience can be achieved. In addition the...
- White papers 2008-09-01
- Switching and Traffic Grooming in WDM Networks
- This paper considers the role of switching in minimizing the number of electronic ports (e.g., SONET ADMs) in an optical network that carries sub-wavelength traffic. Providing nodes with the ability to switch traffic between wavelengths, such as through the use of SONET cross-connects, can reduce the required number of electronic...
- White papers 2008-01-01
- Ethernet as Transport Technology of Choice in Campus Ring Environments
- The demand for more bandwidth is clearly driven by IP-based applications and consequently service providers are looking at infrastructures best support such applications. It has become clear that a packet-centric infrastructure is preferred and it is therefore displacing technologies like SONET, ATM and Frame Relay due to the high cost...
- White papers 2007-07-25
- SURPASS Carrier Ethernet: Focus on Ethernet Ring Protection (ERP)
- Ethernet Ring Protection ERP, part of the Siemens Advanced Ethernet Package, is a network protection mechanism that enables carriers to enjoy an SDH/SONET-like ring protection while leveraging the cost-effectiveness of Ethernet technology. ERP is interoperable with traditional Ethernet and MPLS protection mechanisms, even when other vendors' switches are part of...
- White papers 2006-01-29
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