Lucent Technologies P550 279

Analyzing Network Performance Using RMON and Ethernet Statistics (Layer 2 & Layer 3)

Table 17-1.Interpreting Ethernet Interface Statistics (Continued)

Statistic	Indicates	Actions

Multicasts	Normal during network operation.	Possible causes:
	For example, multicast packets are	•	Too many multicast frames can
	to send target video streams to	•	Too many multicast frames can
	to send target video streams to		consume valuable network
	selected stations on the network,		consume valuable network
	selected stations on the network,		bandwidth.
	and are part of the operation of the		bandwidth.
	and are part of the operation of the	Possible actions:
	Spanning Tree Protocol.	•	Using Intelligent Multicasting
		•	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	Counts of the number of times that	Possible causes:
Redundancy	the number of bits in a frame	•	Defect at the transmitting
Check) or	cannot be divided by 8 (that is,	•	Defect at the transmitting
Check) or	cannot be divided by 8 (that is,		station.
Alignment	cannot be broken into legal octets),		station.
Alignment	cannot be broken into legal octets),	•	Turning equipment on or off.
Errors	and that contain a Frame Check	•	Turning equipment on or off.
Errors	and that contain a Frame Check		This should cause only a few
	Sequence validation error. Typically		This should cause only a few
	Sequence validation error. Typically		errors.
	caused by turning equipment on or		errors.
	caused by turning equipment on or	•	Damaged cables.
	off, and by noise on twisted pair	•	Damaged cables.
	off, and by noise on twisted pair
	segments. These errors can also	•	Interference on network
	result from configuring a network		cabling.
	that does not comply with 802.3	Possible actions (respectively):
	standards. In a standards-compliant	Possible actions (respectively):
	standards. In a standards-compliant	•	Use port error statistics to
	Ethernet network, CRC or	•	Use port error statistics to
	Ethernet network, CRC or		isolate the problem. Check the
	alignment errors represent transit		isolate the problem. Check the
	alignment errors represent transit		transceiver or adapter card
	and receive bit errors.		transceiver or adapter card
	and receive bit errors.		connected to the port where
	The Ethernet standard allows 1 in		connected to the port where
	The Ethernet standard allows 1 in		the problem seems to
	108 bit error rate, but you should		the problem seems to
	108 bit error rate, but you should		originate. Also check the cable
	expect performance to be less than		originate. Also check the cable
	expect performance to be less than		and cable connections for
	1 in 1012 packets. Rates in excess of		and cable connections for
	1 in 1012 packets. Rates in excess of		damage.
	one error per one thousand packets		damage.
	one error per one thousand packets	•	Normal operation, no action
	indicate a serious problem.	•	Normal operation, no action
	indicate a serious problem.		required.
			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.

Cajun P550/P220 Switch Operation Guide

17-3