I can help out with some guidelines and experience.
1. How much bandwidth does Netflow use to collect data from remote routers/switches? Netflow admin guide does not give much detail on how much bandwidth and min/max bandwidth recommandation.
I believe Cisco says that v9 and v5 exporters will use about 1.5% to 3% of the monitored interfaces bandwidth. The exporter traffic at any point is proportional to the number of active conversations and the interface bandwidth, so it varies on any given interface at any time.
2. Does my server orion enough horse power or I need more ram or better processor? Do I need a better server?
3600 exporters is a lot to monitor. I would get the best hardware you can. The SQL server cannot be on a VM, this will cause huge performance issues.
3. Sql server(the same spec with Orion server) capable handle the data collecting workload for 3600?
Again, the bigger the better. See the tips posts about using dedicated storage for the SQL server. The specified item was not found.
The specified item was not found.
4. What're some of the way to optimize Netflow bandwidth over on wan Cisco routers/switches?
Not sure exactly what you are asking here. You could deploy sampled netflow on the routers and switches to minimize the load on all the systems.
Hope this helps
Netflow bandwidth is pretty nil. The only issue you might have is how much bandwidth would be used at the head end where the collector is considering your large number of exporters.
Also that is A LOT of netflow. You will need a VERY beefy SQL and Orion server (basically as much as they will let you spend) not to mention your DB will be huge. SolarWinds has a post on this board on ways to tweak netflow for performance I would institute them all in your situation.
You might also want to purchase an additional netflow license so you can put netflow on a box of its own so you do not swamp your Orion box.
That will work if you get an additional NPM license and run the two independently of the other NPM instance. The additional NetFlow receiver alone only helps for source reachability issues as it still writes to the NPM database.