[c-nsp] SNMP descrepancy

j.vaningenschenau at utwente.nl j.vaningenschenau at utwente.nl
Wed Jun 23 11:54:53 EDT 2010


> Actually, the 'public at 643' community he has there gives the table for
> VLAN 643.

True, he's using community based indexing, so it's related to VLAN 643.
But Phil is correct about polling the wrong OID: TS is looking at
BRIDGE-MIB::dot1dTpFdbAddress, not ipNetToMedia.
 
> And I've seen that sort of thing before, and it seems to be random
> (there's probably some rhyme or reason, but I've learned that if I get
> the table via SNMP multiple times, at different times of day, it
> eventually catches it all).

Please note that aging time in MAC forwarding table is often not the
same as the age timer in ARP tables. Which, by the way, can lead to nice
unicast flooding effects. But that's a different story.

IIRC, default age time for MAC forwarding table is 300 seconds (IEEE
spec?).


Regards,

Jeroen van Ingen
ICT Service Centre
University of Twente, P.O.Box 217, 7500 AE Enschede, The Netherlands



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