Understanding Bit Error Thresholds - Cisco Nexus 5000 Series Configuration Manual

Configuring Fibre Channel Interfaces
DETAILED STEPS
Command or Action
Step 1
switch# configuration terminal
Step 2
switch(config)# interface fc slot/port
Step 3 switch(config-if)# switchport fcrxbufsize 2000

Understanding Bit Error Thresholds

The bit error rate threshold is used by the switch to detect an increased error rate before performance degradation
seriously affects traffic.
The bit errors can occur for the following reasons:
• Faulty or bad cable.
• Faulty or bad GBIC or SFP.
• GBIC or SFP is specified to operate at 1 Gbps but is used at 2 Gbps.
• GBIC or SFP is specified to operate at 2 Gbps but is used at 4 Gbps.
• Short haul cable is used for long haul or long haul cable is used for short haul.
• Momentary synchronization loss.
• Loose cable connection at one or both ends.
• Improper GBIC or SFP connection at one or both ends.
A bit error rate threshold is detected when 15 error bursts occur in a 5-minute period. By default, the switch
disables the interface when the threshold is reached.
You can enter the shutdown/no shutdown command sequence to reenable the interface.
You can configure the switch to not disable an interface when the threshold is crossed.
The switch generates a syslog message when bit error threshold events are detected, even if the interface
Note
is configured not to be disabled by bit-error threshold events.
To disable the bit error threshold for an interface, perform this task:
Cisco Nexus 5000 Series NX-OS SAN Switching Configuration Guide, Release 5.2(1)N1(1)
22
Purpose
Enters configuration mode.
Selects a Fibre Channel interface and enters interface
configuration mode.
Reduces the data field size for the selected interface to 2000
bytes. The default is 2112 bytes and the range is from 256 to
2112 bytes.
Configuring Fibre Channel Interfaces
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