[j-nsp] Interface Index(ifIndex) changes when router is rebooted

[Chris Adams]

Once upon a time, Paul Stewart <paul at paulstewart.org> said:
> I have to agree here - having the monitoring software "rediscover" where the
> ifindex for an interface is after a reboot isn't ideal in my opinion.....

It is a case you have to handle anyway.  What if you upgrade REs, or you
have REs die and you have to replace them?  The index values will change
then anyway.  How do you handle that?  Do you manually update your
monitoring configs?

All the information is provided in SNMP, you just need to use it.  My
monitoring and management scripts walk and cache ifDescr to find the
desired interface and then use the ifIndex.  Every time they fetch
something for an interface, they include the ifDescr.  If the ifDescr
still matches, that's all it takes.  If it is different, the scripts
discards the ifDescr cache and re-walks the ifDescr tree.

This is one of the reasons I switched from MRTG to Cricket 10+ years
ago; I configure Cricket to graph "so-0/2/1", not "17".  Who knows what
"17" is; "so-0/2/1" is pretty obvious.

-- 
Chris Adams <cmadams at hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.