This article contains information about cyclic redundancy check (CRC) error on a NetScaler interface.

Cyclic Redundancy Check Error on a NetScaler Interface

CRC value is created by the sending device and is recalculated by the receiving device to check for damage that might have occurred to the frame in transit. The nic_err_rx_crc counter tracks the number of received packets with CRC errors received on the specified interface.

An increment in the nic_err_rx_crc counter generally indicates noise or transmission problems on the LAN interface or the LAN bus. A high number of CRC errors are usually the result of collisions or a station transmitting bad data or malfunctioning Ethernet device.

The issue might be with the NetScaler interface or the interface on the Switch or the Router connected to the NetScaler appliance.

Run the following command to check the interface errors on Cisco Switch or Router:

show interfaces ethernet [slot | port]

If there is no error count on upstream Switch or Router, run the following command to verify if the nic_err_rx_crc counter is increasing on the appliance:

1. Go to shell prompt (Type "shell" in CLI, Example: >shell )
2. Navigate to directory /var/nslog (Command: # cd /var/nslog)
3. Run the following command: "nsconmsg -K newnslog -g nic_err_rx_crc -s disptime=1 -d current"

Example:
> shell
root@ns# cd /var/nslog
root@ns# nsconmsg -K newnslog -g nic_err_rx_crc -s disptime=1 -d current
Displaying performance information
NetScaler V20 Performance Data
NetScaler NS12.1: Build 57.18.nc, Date: Jun  9 2020, 11:36:40   (64-bit)
 

Complete the following steps to troubleshoot NetScaler 0/1 interface flapping issue:

1. Look for any interface getting muted or L2 MAC moves errors in newnslog on NetScaler.
2. Look for any CRC errors in newnslog files as mentioned in this article  http://support.citrix.com/article/CTX135215.
3. If the errors are RECEIVE errors then this means they are (usually) caused by something outside of the NetScaler (cables, switch port, SFPs). Being these are receive errors, very rarely are they caused by NetScaler hardware being bad, especially considering these are on different NICs (built-in on motherboard for 0/1, and a card for 1/3).
4. Troubleshoot the CRC errors by swapping cables, SFPs (if used), and switch ports, in that order, to see if the problem moves/goes away, in order to identify the cause.