2. developing service metrics
๏ Service metrics:
๏ To measure and how to improve
customer interactions and satisfaction.
๏ To help analyze trends and overall
performance of Services and Service
Management processes.
๏ Performance thresholds and limits and
performance characteristics are
measured.
3. developing service metrics
๏ Service metrics are either actual
measurable quantities or measured
quantities in the network.
๏ Performance characteristics must be
configurable, measurable and verifiable
within the network.
๏ The types of service metrics you use will
depend on your design and the types of
equipment.
4. developing service metrics
๏ Service metrics for RMA include:
๏ Reliability: in terms of Mean Time Between
Failures (MTBF) and Mean Time Between
Mission-Critical Failures (MTBCF)
๏ Maintainability: in terms of Mean Time To
Repair (MTTR)
๏ Availability: in terms of MTBF, MTBCF,
MTTR.
๏ Optionally Uptime and Downtime (as a
percent of total time).
5. developing service metrics
๏ MTBF: Mean Time Between Failure.
๏ A basic measure of reliability.
๏ It is the predicted elapsed time(period of time)
between inherent failures of a system during
operation.
๏ it can be calculated as the arithmetic
mean (average) time between failures of a system.
๏ where all failures that occur over an operating period
are counted.
๏ It is sometimes referred to as logistics reliability
because it determines the number of spares that you
will need to replace items (e.g., parts, assemblies,
etc.) that fail.
6. developing service metrics
๏ MTBCF : Mean Time Between Critical
Failure.
๏ It is sometimes referred to as "mission reliability"
๏ It is a subset of MTBF because it only counts
those failures that result in a mission abort or
mission failure.
๏ It is a term used when redundancy exists in a
system.
๏ It is often used to differentiate system reliability
from series mean time between failure (MTBF).
7. developing service metrics
๏ Service metrics for capacity include:
๏ Data rates, Peak Data Rate(PDR)
๏ Sustained Data Rate(SDR)
๏ Minimum Data Rate(MDR)
๏ Data sizes:
๏ Burst sizes and durations.
8. developing service metrics
๏ Service metrics for delay include:
๏ End to end or
๏ Round-trip delay
๏ Latency
๏ Delay variation
๏ Service metrics can be described in
terms of variables in network devices:
๏ Simple network management protocol(SNMP)
๏ Common management information protocol(CMIP)
9. ๏ Examples of variables used as service
metrics include:
๏ Bytes in/out (per interface)
๏ IP Packets in/out (per interface)
๏ Dropped Internet control message
protocol(ICMP)
๏ Service Level agreement (SLA) metrics(per
user)
โ Capacity limit.
โ Burst tolerance.
โ Delay.
โ Downtime.
10. Important terms for definition
๏ FRAME RELAY:
๏ Standardized WAN specifies physical and
logical of digital telecommunication channels
using packet switch methodology.
๏ Designed for transport across Integrated
Service Digital Network(ISDN) Infrastructure.
11. Important terms for definition
๏ UP-TIME :
๏ Time during the computer is operational.
๏ DOWN-TIME :
๏ Time during the computer is NOT
operational.
๏ CELL LOSS RATIO :
๏ Field of ATM (Asynchronous transfer mode),
cell header, indicate the ratio of discarded
cells to that are transmitted successfully.
12. Important terms for definition
๏ CMR:
๏ Cells received at the end point that was not
originally transmitted by source end,
associated with given traffic load and
destination.
๏ PACKET LOSS RATIO:
๏ Rate at which packet of data travelling
across a network failed to reach destination.
โ ACTIVE โ specify link information of packet of
priority
โ PASSIVE โ know only source and destination.
13. Important terms for definition
๏ PACKET ERROR RATE:
๏ Number of incorrectly received data packets/
total no of received packets.
๏ BIT ERROR RATE:
๏ The number of bit errors is the number of
received bits of data stream over a
communication channel has been altered
due to noise interference, distortion or bit
synchronization errors.
14. Important terms for definition
๏ BURST TOLERANCE:
๏ Parameter defined by ATM FORUM (ATM in
Telecommunication network) for ATM traffic
management.
โ Ex: VBR determines the size of the maximum
burst of contiguous cells that can be
transmitted.
15. MEASUREMENT TOOLS
๏ Various tools to help measure service
metrics:
๏ Utility ping(TCP/IP)
๏ Roughly measures round-trip delays
between selected sources and destinations
in the network.
๏ Trace-route:
โ path traces.
๏ TCP dump:
โ Tool to analyze TCP traffic.
16. WHERE TO APPLY SERVICE METRICS
๏ It is useful when trying to isolate and
track problems in the network.
๏ Especially when there are multiple
groups responsible for the network.
๏ Used to separate responsibilities
between
๏ An End โto-End provider,
๏ A WAN service provider, and other
immediate providers.