NS3000/iX Operations and Maintenance Reference Manual (36922-90042)

206 AppendixA
LINKCONTROL Command
NS 3000/iX 100VG-AnyLAN Link Statistics
PROBE. This does not include multicast frames received but dropped
for any reason. Upper layer protocols register desired multicast
addresses with the link driver during initialization. The maximum
printable value of this 64-bit field is 17 digits, or about 99 million billion
frames. In the previous example, 1.30 million multicast frames were
received at normal priority and forwarded to upper layers.
Recv multicast hipri — Total number of frames addressed to a
multicast address which were successfully received over the medium at
high (demand) priority and forwarded to an upper layer protocol such
as PROBE. This includes multicast frames for which normal priority
was originally requested by the sender, but which were later
automatically priority-boosted by the 100VG-AnyLAN network. It does
not include multicast frames received but dropped for any reason.
Upper layer protocols register desired multicast addresses with the link
driver during initialization. The maximum printable value of this 64-bit
field is 17 digits, or about 99 million billion frames. In the previous
example, no frames have been received at high priority.
Receives no error — Total number of frames the adapter card reports
it successfully received over the medium. These adapter card statistics
are periodically read, and are accumulated by the link driver. This
includes both normal and high (demand) priority frames. It does not
include any frames the adapter card detected errors against. The total
should approximate the sum of all frames forwarded to upper layer
protocols, plus all frames dropped for any reason. The maximum
printable value of this 64-bit field is 17 digits, or about 99 million billion
frames. In the previous example, 6.64 million frames were received
successfully by the adapter card, then either forwarded or dropped.
Recv dropped: addr — Total number of frames received by the
adapter card, but dropped because no upper layer protocol had
requested future reception of those frames, or because that protocol
unbound itself from the link while the received frame was still in
motion. Older, intelligent adapter cards can invisibly receive and drop
these frames, often without ever reporting them as statistics. But
today’s adapters are not intelligent, and require link driver
involvement. For users unfamiliar with seeing it, this statistic may
seem excessive. But it is important because it gives an indication of the
amount of unnecessary traffic present on the network segment to which
the adapter card is connected. High values may indicate a need to
resegment the network, since systems and their adapters are spending
a large amount of time and resources recognizing and dropping frames
they do not care to see. High volumes of such traffic can also limit
network bandwidth. The maximum printable value of this 64-bit field is
17 digits, or about 99 million billion frames. In the previous example,
out of 66.4 million frames received, 16.0 million have been dropped
based on address: about 24% of all frames received are then being
dropped. This level would be considered typical or perhaps a little high.