Non-volatile feature of ifAlias

RFC 2233 specifies that if an SNMP agent supports the ifAlias OID variable, then its value must not change during a router reboot:

... the ifAlias name is non-volatile, and thus an interface must retain its assigned ifAlias value across reboots, even if an agent chooses a new ifIndex value for the interface.

Thus, if the router supports ifAlias, PI SNMP can be configured so that it will collect correct data even after a router reboot. To find out whether the router supports ifAlias, run a command such as the following:

C:> snmpwalk -M .\mibs 10.8.10.1 public .1.3.6.1.2.1.31.1.1.1.18

For the above commands, use the IP address of the router and the correct community string. If the above command results in items similar to

ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.1 = to ISP
ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.2 = to LAN
ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias.3 = remote office

then the router supports ifAlias. If the results do not contain

ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifAlias

then the router does not support ifAlias.