|This MIB module describes, stores, and reports outage
related information generated by individual hardware
and software components comprising a router. They includes
physical interfaces, logical interfaces, physical
entities such as chassis, slots, modules, ports,
power supplies, and fan, software processes
running on each card, and logical entity, which can be
defined by outage monitoring program,
which are IOS software for each LC and RP,
router device, and CPU utilization.
The outage related information comprises entity or
interface up and down, process start and abnormal
or normal termination, unusually high CPU utilization
caused, for example, by Denial of Service (DoS) attack,
The outage related event can be collected by means of
Cisco's fault manager, Cisco's event manager, and
syslog messages, etc.
An outage manager maintains the following outage data
for each component.
1) Accumulated Outage Time (AOT): total outage
time of a component from the beginning of
2) Number of Accumulated Failure (NAF): total
number of failure instance from the
beginning of the measurement.
3) Recording Start Time (RST): the date-time
that the measurement process began against the object.
Using aforementioned outage data, users can calculate
and correlate to derive availability information as
1) Component Availability: the probability
that a component will operate when needed.
= (1 - (Outage Time / Duration))
2) DPM (Defects per Million): measure(s) of the
defects of the system that have an immediate
impact on the end-user.
= ([AOTi / (Measurement Interval)] x 10**6)
3) MTTR(Mean Time To Recovery): expected average
time to restore a failed component.
= (AOTi / NAFi)
4) MTBF (Mean Time Between Failure): expected
average time between failures of a component.
= (T2 - RSTi) / NAFi
5) MTTF (Mean Time To Failure): the mean time to
failure once the device starts working.
= (MTBFi - MTTRi = (T2 - RSTi - AOTi) / NAFi)
System Up @------|-------------------|----> Time
At the beginning RSTi:
tmp_AOT = AOTi (from the MIB polling);
At the end T2:
Duration = Current Time(T2) - RSTi;
Outage Time = AOTj - tmp_AOT;