Real-Time IP Network Redundancy in Connection to Mobile Media Gateway Sanna Santajärvi S-38.310 Tietoverkkotekniikan diplomityöseminaari 18.05.2004

Basic Information Thesis written at Oy L M Ericsson Ab Supervisor: Heikki Hämmäinen, Professor Instructor: Juha Eloranta, M.Sc.

Contents Background Research Description Research Methods Basic Concepts

Background Heavy investments are being made by the Mobile Network Operators (MNO) to the mobile networks Certain Service Level has to be maintained even in special situations (e.g. link failure, congestion)

Relationship between the Service Level and costs Research Description Around Media Gateway node IP network redundancy Redundant network possible but costly Relationship between the Service Level and costs

Research Methods Literature Survey Interviews Technical Specifications by 3GPP Researches, studies, and white papers from different acedemic and comercial sources Interviews Assisting method Ericsson experts in different fields

Basic Concepts (1) REDUNDANCY Systems or elements of a system are backed up with secondary resources Tradeoff between higher investments and costs caused by the system downtime

Basic Concepts (2) Fault Error Failure FAULT – a physical defect in some component ERROR – deviation from the required operation FAILURE – system’s inability to perform its function

Basic Concepts (3) RELIABILITY – probability that the system functions correctly over a period of a time Mean time-to-failure (MTTF) Mean time-to-repair (MTTR) AVAILABILITY – probablity that the system is functioning correctly at a given time = MTTF / (MTTF + MTTR)

The ’nines’ 1 nine 90.0% 36 days 12 hours 50 000 minutes Availability Downtime/year Downtime/year Examples 1 nine 90.0% 36 days 12 hours 50 000 minutes Personal Clients 2 nines 99.0% 87 hours 36 minutes 5000 minutes Entry-level Businesses 3 nines 99.9% 8 hours 46 minutes 500 minutes Internet Service Providers, Mainstream Businesses 4 nines 99.99% 52 minutes 33 s 50 minutes Data centers 5 nines 99.999% 5 minutes 15 s 5 minutes Carrier-grade Telco, Medical, Banking 6 nines 99.9999% 31,5 s 0,5 minutes Military Defense System, Carrier-grade Goal

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