The type of the IP SLA entry.
echo(1) - Specifies that the IP SLA entry collect the
round-trip-time data for a destination host. The IP
SLA entry MUST use a probe of type 'icmpTs'.
jitter(2) - Specifies that the IP SLA entry collect the packet
delay variation (jitter) and round-trip-time data
for a destination host. The IP SLA entry MUST use
a probe of type 'icmpTs'. Both the source and
destination hosts MUST have clock synchorinzation
enabled for accurate packet delay variation data.