Transcript Research Methods

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
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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)
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
– 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’
Nines
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
Questions?
Thank you