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Unformatted text preview: Study of IP Dependability W.Chen, C. Hu & A.Sand 02/09/99 Page 1 of 45 Document number: //B. Aris/ Integrity / Study of Network Dependability.doc Issue: 1.0 Status: Draft Prepared by: Wenfeng Chen (0V13), Chenjiang Hu (0V13) and Allan Sand (6M21) Date: Feb 4. 1999 © Copyright Northern Telecom 1998 This document is the property of Northern Telecom who own the copyright therein. The information in this document is given in confidence and without the written consent of Nortel Networks given by contract or otherwise, the document must not be copied, reprinted or reproduced in any material form either wholly or in part nor must the contents of the document or any Study of IP Network Dependability (Project Summary and Technical Recommendations) Study of IP Dependability W.Chen, C. Hu & A.Sand 02/09/99 Page 2 of 45 0. Summary 0.1 Problem Statement Although today’s IP-centric networks implement a comparatively rich set of fail-over mechanisms to mitigate service outage from failures at the transport and switching levels, today’s IP networks continue to experience connectivity outage, degraded throughput, and long delays. The problem is attributed to congestion and discarded packets from poor routing protocol performance in the form of routing anomalies such as (1) connectivity alternations or losses, (2) routing loops, (3) route fluttering, and (4) excessive hops in route. Other studies show that failures in IP networks (hardware/software problems and operational errors) are much more frequent than in today’s well-maintained PSTNs. The objectives of 98 IP-Centric Dependability Program were: 1) To develop a competency in modeling and analysis of large IP-centric networks. Abstract relevant details and key dependencies from designs of layer 1, 2 and layer 3. 2) Use this competency to provide draft engineering-guidelines for building dependable and predictable large IP-centric carrier networks. Focus on network recovery from failure (link/node) conditions under various traffic levels, network topologies, routing protocols, redundancy levels, and recovery mechanism. Prioritize effort to available models. 3) Develop an approach to map between service availability, routing convergence time and network redundancy. 4) Develop an ongoing dialog with other OPNET and IP modeling teams. Where possible, cascade designs and lessons learned. 5) Engage a large greenfield IP service provider such as Level 3 and establish a favoured supplier status by providing them with network dependability engineering guidelines. 0.2 Approach In 1998 we were successful in building a competency of analytical and simulation modeling towards understanding and quantifying the factors affecting restoration time in IP networks....
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This note was uploaded on 08/08/2011 for the course CS 310 taught by Professor Aartisingh during the Spring '11 term at National Institute of Technology, Calicut.
- Spring '11