Network Interface Errors

SUMMARY

Network Interface Errors

ISSUE

Symptoms / Description

If you suspect network connection issues caused by overburdening of the Unitrends Network Adapter from high throughput, you may run the command “ethtool -S ethX | egrep 'errors|failed|collisions' | grep '[1-9]'” where ethX is the active port on the Unitrends device and it returns alloc_rx_buff_failed issues then you have a buffer overflow.

Cause

This is caused by too many requests flooding the Unitrends appliance all at once and can be resolved by allocating more memory to the buffer process.  This is a rare issue typically seen if openVPN is used on a very fast connection (approaching or exceeding gigabit speed). 

Resolution / Workaround / Execution Process

See what the max value of the interface is, using eth0 as an example:

# ethtool -g eth0

The following is a sample output:

Ring parameters for eth0:

 

Pre-set maximums:

RX: 1024

RX Mini: 0

RX Jumbo: 0

TX: 1024

Current hardware settings:

RX: 256

RX Mini: 0

RX Jumbo: 0

TX: 256

In this example, 1024 is the maximum RX and TX buffer size for this particular driver, and the current buffer size is 256.



Run this command to make the change on the fly, then monitor for some time to see if the issue is resolved:

# ethtool -G eth0 rx 1024 tx 1024

To make the change permanent, add the following entry to the bottom of /etc/rc.d/rc.local start-up script:

# ethtool -G eth0 rx 1024 tx 1024

 

Third-Party Sources

http://firewalltipss.blogspot.com/2011/06/how-to-increase-sizes-of-buffer-ring.html

 

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