On 2012-09-24 14:48 , Joe Loiacono wrote:
Peter Phaal <peter.phaal@gmail.com> wrote on 09/23/2012 12:23:57 PM:
Exporting packet oriented measurements doesn't mean that you have to loose ingress/egress interface data.
Note that you get these in NetFlow too. Depends on which version you pick or how you combine your template and of course if the hard and software allows it, but it is there.
In the specific example being
discussed (sFlow export), detailed forwarding information from the router forwarding plane is exported with each sampled packet header (full AS-path if you are using BGP).
Wrt AS-path, I don't get how this happens. Since this is important to this community, could you explain?
As sFlow runs on the same box that knows the BGP tables the packets sflow packets get that information too. No magic there. This can also be done with NetFlow/IPFIX though, as shown in: http://www.pmacct.net/building_traffic_matrices_n49.pdf thus by combining a BGP feed with the NetFlow/IPFIX feed. There is of course a small chance in such a setup that the tables mismatch and is not the same as the router would have made it. Then again with sFlow you typically sample and thus you have windows of loss anyway... Note that there are IPFIX/NetFlow enabled boxes which also include BGP details if one is worried about that, though if your path changes mid-flow you have a slight error there too again. Greets, Jeroen