As the integrated netflow feature only supports up to 8 interfaces simultaneously, we decided to set up an external server to collect netflow data for further processing. Since our hardware is quite capable (we thought), we activated netflow on all ~200 interfaces (mostly VLAN) at once which basically crashed the whole system. Of course the primary lesson of this is, to never ever and under no circumstances do anything on more than 10 interfaces at once, unless you're begging for trouble and feel a really strong urge to bring in cake on the following day which is how we usually deal with colleagues accidentally breaking something. ;-)
But seriously, how much load is there to be expected per interface sending netflow data to an external server? Does it depend on the amount of traffic on that interface or is that irrelevant? Is activating netflow on literally hundreds of interfaces something that a well-equipped system should be able to handle or is it way beyond of what any powerful system can do?
At the moment this is not about identifying problems and finding tuning options to solve them - it's about making sure that what we want to do is something that actually can be done.
Thanks
Thomas