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)
○ Capacity limit.
○ Burst tolerance.
○ Delay.
○ 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.
○ ACTIVE – specify link information of packet of
priority
○ PASSIVE – 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.
○ 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:
○ path traces.
TCP dump:
○ 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 –to-End provider,
A WAN service provider, and other
immediate providers.