[c-nsp] NetFlow for Bandwidth Billing

[TCIS List Acct]

Adrian Chadd wrote:
> On Wed, May 02, 2007, TCIS List Acct wrote:
> 
>>> There is no netflow solution that's perfect for every network, so you'll 
>>> want to do some legwork. Despite my experience, I can't personally 
>>> recommend any particular toolset, since I've always rolled my own. (No, I 
>>> don't currently have a flow analyzer that I can release.)
>> Our main concern is bytes in/out for billing purposes.  Nothing fancy, but we 
>> will be sending NetFlow streams from 3-4 different core routers which the 
>> NetFlow Analyzer must aggregate and consolidate into a single report per-IP or 
>> per-subnet, depending on the customer.
> 
> Its probably not going to be a big deal for a single-POP colocation provider,
> but consider your network topology when deploying Netflow. You don't want to
> double/triple account flows and you have to assume some traffic will be asymmetric
> and thus show up as two flows - each router seeing one direction of the traffic.

Yes, we will have that situation (asymmetric flows) where data comes in one link 
and out another, which is why we want to use a NetFlow analyzer that is smart 
enough to deal with such a situation/aggregate the data in an intelligent way. 
We are willing to buy a commercial product if that is what it takes, provided 
the pricing is reasonable.  Several open source products have been suggested as 
well, such as http://www.pmacct.net/

My main concern is to understand the implications of using NetFlow for bandwidth 
billing, and if there are any major reasons "not" to do it this way.

--Mike