METRODATA NetTESTER FAMILY USER MANUAL
76-02-107 Rev.A
Page 43 of 133
FTD/IFDV
Percentile
In order to comply with the SLA, FTD and
IFDV parameters must be satisfied by a
portion of packets specified by this percentile
value.
MTU
Maximum
Transmission Unit
Performance parameters apply only to
packets up to the size specified. Larger
packets may be passed at the provider's
discretion, with no performance assurances.
Colour-
Marking
The SLA may include the option for the
customer to colour-mark traffic, such that
'green' traffic gets priority use of CIR/CBS
bandwidth. In this case, a colour-marking
system must be agreed.
9.2 SLA Definition and Use
Up to 16 SLAs may be defined on the unit. These can then be used in two different
places:
1. By attaching to a service activation test peer (see section 10), the SLA is used to
set test parameters and mark results as pass or fail;
2. By attaching to an in-service performance monitoring session (see section 12), the
SLA can be used to generate warnings when the performance ceases to comply with
the agreement.
9.3 One-Way vs Two-Way Delay Measurements
In accordance with MEF, SLA delay and delay-variation (FTD and IFDV) values refer
to the travel of a packet over the service in one direction or the other.
The unit does not support clock-synchronisation systems that would make
measurement of one-directional delays possible.
In the case of one-directional delay variation measurements, these can be made in
the case of performance monitoring, but not for service activation testing.
This means that the one-way performance statistics required to monitor SLA
compliance must, in some cases, be estimated from two-way ('round-trip') figures.
