[rtg] Fwd: Results with RTG

[John Von Essen]

Netflow is not good at all for bandwidth billing or accurately  
gauging bandwidth usage (clients, upstream, etc.,.)

Its great for troubleshooting and design, but for total bandwidth  
stats, depending on the environment and sampling, it can be WAY off.  
I had a customer who pushes a solid 20Mbps a day, but his Netflow  
graphs were only showing 4Mbps.

Also, depending on your Cisco, there is a performance hit, and you  
may have to bump up the sampling considerably. I use FlowViewer and  
flow-tools, and when I need to investigate something, I turn it on  
and collect, then turn it off when I am done.

-John

On Mar 9, 2009, at 1:07 PM, Brent Imhoff wrote:

> Harry Marcson wrote:
>> Is netflow actually more accurate? Our cisco gear does support  
>> netflow, but we have never tested it, I could not find an  
>> opensource solution to try, but will do some more searching.
> I wouldn't say more accurate but it can give you some interesting  
> insights depending on what you're looking for.  If you wanted to  
> know how much of your traffic was destined for a particular AS or  
> if you wanted to see how much of your data matched particular port  
> numbers (to attempt to predict application usage), those would be  
> great applications for netflow.
>
> Since most netflow implementations are sampled, meaning you're only  
> collecting 1 of every 100-1000 packets, I wouldn't recommend it for  
> billing.  Of course, YMMV depending on the size of the network..   
> The smaller it is, the easier it is for the router to generate flow  
> stats.
>
> cflowd is a decent linux opensource collector.  You'd be on your  
> own to generate useful information out of it.  http:// 
> www.paessler.com has a windows based product.  No idea if it's good  
> or not.  Linux based product: http://neye.unsupported.info/ but  
> again, no idea if it works well or not.  One that I have  
> implemented at previous employers is from Arbor Networks (I'm not  
> affliated with them).  That product is really great, but you'll pay  
> dearly for it.
>
> -brent
>> --------------------------------------------------------------------- 
>> ---
>>
>> _______________________________________________
>> RTG mailing list
>> RTG at lists.grdata.com
>> http://lists.grdata.com/mailman/listinfo/rtg
>>
>
> _______________________________________________
> RTG mailing list
> RTG at lists.grdata.com
> http://lists.grdata.com/mailman/listinfo/rtg