Filter
Top Products
Cajun P550/P880 /P882 Switch User Guide
Analyzing Network Performance Using RMON and Ethernet Statistics
19-5
Multicasts Normal during network
operation. For example,
multicast packets are to send
target video streams to selected
stations on the network, and are
part of the operation of the
Spanning Tree Protocol.
Possible causes:
• Too many multicast frames
can consume valuable
network bandwidth.
Possible actions:
• Using Intelligent
Multicasting can
significantly reduce
multicast traffic on
individual ports.
• Segmenting the network
into smaller VLANs and
routing between them can
also help control
proliferation of multicasts.
CRC (Cyclic
Redundancy
Check) or
Alignment
Errors
Counts of the number of times
that the number of bits in a
frame cannot be divided by 8
(that is, cannot be broken into
legal octets), and that contain a
Frame Check Sequence
validation error. Typically caused
by turning equipment on or off,
and by noise on twisted pair
segments. These errors can also
result from configuring a
network that does not comply
with 802.3 standards. In a
standards-compliant Ethernet
network, CRC or alignment
errors represent transit and
receive bit errors.
The Ethernet standard allows 1
in 10
8
bit error rate, but you
should expect performance to be
less than 1 in 10
12
packets. Rates
in excess of one error per one
thousand packets indicate a
serious problem.
Possible causes:
• Defect at the transmitting
station.
• Turning equipment on or
off. This should cause only a
few errors.
• Damaged cables.
• Interference on network
cabling.
Possible actions (respectively):
• Use port error statistics to
isolate the problem. Check
the transceiver or adapter
card connected to the port
where the problem seems to
originate. Also check the
cable and cable connections
for damage.
• Normal operation, no action
required.
• Check cables for damage.
• Inspect cable runs to see if
they are too close to noisy
devices, and check for
problems with network
devices.
Table 19-1. Ethernet Interface Statistics Dialog Box Fields continued
Statistic Indicates Actions