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Author Topic: Nedi x ifindexes.  (Read 2594 times)

dirtyal

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Nedi x ifindexes.
« on: August 25, 2009, 04:15:09 PM »
Hello, does someone know how Nedi deals with interfaces that have their index changed, like when you plug a new module on a router or even maybe for virtual interfaces? Does is update the database on a new discover?
   Tks a lot.

rufer

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Re: Nedi x ifindexes.
« Reply #1 on: August 25, 2009, 04:43:26 PM »
It will rediscover the hosts that are online at the next discover. But offline hosts will probably be wrong after that.

With cisco IOS, you can configure "snmp ifmib ifindex persist", and IfIndex won't change any more. I would highly suggest to do so.

Greetings
rufer

shadowcaster

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Re: Nedi x ifindexes.
« Reply #2 on: August 27, 2009, 01:02:15 PM »
This is a bad idea. According to rfc, key for interface must be it's name, not index. indexes are dynamic and may (and probably will) change after reboot/reconfiguration. The outstanding example can be hp switch 1800-8G, that have ifindex like 1 for ip virtual interface, and 101-108 for ether, but in lldp branch have indexes like 1-8 for ports.

rufer

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Re: Nedi x ifindexes.
« Reply #3 on: August 27, 2009, 03:52:37 PM »
I can't see whats wrong with persistent ifindex as long as the interface names stay constant. The ifIndex can be completely random.
For instance we have tools that rely on ifindex and that's why we use ifindex persistence.

Greetings
Rufer
« Last Edit: August 27, 2009, 03:54:22 PM by rufer »

rickli

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Re: Nedi x ifindexes.
« Reply #4 on: August 27, 2009, 04:56:10 PM »
That's why I designed NeDi to use the actual names. Indexes are only for internal reference during the discovery and should not really affect nodes and graphs. However some devices use poorly implemented mibs, which require some "fumbling" with indexes...
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