What the difference between ifIndex and persistentifIndex?

[evens]

In the agents_all_view table in NFA, there are 2 fields: ifIndex and persistentifIndex.   The ifIndex sometimes changes in the Cisco router when the "snmp-server ifIndex persists" statement is missing at a time when changes occur in the cisco router.   NFA keeps track of the ifIndex which is used to assign licenses to interfaces and so when an ifIndex changes, the new ifIndex may not point to a license and so causes the interface to go inactive.  I am tracking all interfaces that become inactive daily and need to track the ifIndex also.  But I need explanation about the relationship between the ifIndex and persistentifIndex in NFA.

[Melanie_Giuliani]

Hi evens,

 

I've moved this question into the CA Infrastructure Management community under the NFA category where it's more likely that product experts will see it and respond.

 

Thanks!

Melanie

[Anon Anon]

Hi Evens,

The persistentIfIndex is the key that NFA will always use to point to the same interface.

ifIndex is the index key that the router knows the interface by at the current point in time. It is possible for an interface to change ifIndex, sometimes in an OS upgrade - sometimes in a reboot, but NFA needs to know it is in fact the same interface.

Thanks,
Marc

[evens]

Thanks.   That’s great.

 

Regards

 

 

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Marc-Evens Gracieux (Evens)

Sr. Network Engineer| Operations System Support (OSS)

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