Version

Argent for SNMP 3.1A-1501-C and earlier

Date

Thursday, 26 March 2015

Summary

The bandwidth usage (Mbps) collected by DeviceMagic may show negative number occasionally

It is more likely to happen for very busy switches

The issue has been addressed in Argent for SNMP 3.1A-1501-T4

Technical Background

DeviceMagic calculates switch bandwidth usage by calculating the Delta value of IN/OUT octets of switch ports

The IN/OUT octets are stored in switch as 32-bit counter

As a result, the number is reset after 2³²

If the number happens to be reset between two consecutive poll, the Delta value will be negative as well as the calculated Mbps

The number should be adjusted by adding 2³²

Resolution

Upgrade to Argent AT 3.1A-1501-T4 or later