SNMP relies on "ifIndex", which is determined by the Linux kernel.
When several types of NICs are installed, which use different NIC drivers, Linux kernel 2.6 loads the NIC drivers in random order (can be seen in '
/var/log/dmesg' file, in output of '
ip link', in output of '
This adversely affects SNMP monitoring by "IfIndex", since "IfIndex" will be different each time.
According to RFC 2863 - Section 3.1.5 the interface numbering may change at a reinitialization of the snmp agent (for example during a reboot) and the management station has to accommodate the interface table whenever the value of "sysUpTime" is reset to zero.