On 4/1/15 6:50 PM, William Waites wrote:
I run a small network composed of even smaller networks each
encapsulated in an autonomous system. I'd like to do traffic
accounting using netflow aggregated by ASN. My border routers run
FreeBSD and BIRD.

Right now, and this is mentioned in ng_netflow(4), we do not fill in
the source and destination ASN because there is no information to get
this from the routing daemon's RIB. Probably if we come up with such a
way it should be generic so it could be used by Quagga, BIRD or
OpenBGPD.

I've done a little bit of thinking about how this could be done, and
come up with two main strategies:

   1. A new kind of netgraph node inserted before ng_netflow knows how
      to query the routing daemon and decorates the packet with the
      result, which ng_netflow then puts into the flow packet if
      present. This entails either a copy (tee) or putting the lookup
      in the data path which may be suboptimal.

   2. A new hook added to the ng_netflow node that allows it to query
      the routing daemon through a different new kind of netgraph
      node. This is probably better but may be slightly more
      complicated to implement.

Is anyone working on this or has given this though? I wasn't able to
find much by searching the list archives. It may be that I will soon
have some students that I can set on this task but would not like to
unnecessarily duplicate effort.

there is no reason the netflow node could not be modified to make external requests.. it could certainly spawn off a worker thread that could do those sorts of things.

Cheers,
-w

--
William Waites <wwai...@tardis.ed.ac.uk>  |  School of Informatics
    http://tardis.ed.ac.uk/~wwaites/       | University of Edinburgh
        http://www.hubs.net.uk/            |      HUBS AS60241

The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

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