[Click] FromDAG

[Marco Canini]

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Hi,

endace cards are indeed very expensive.

It is possible to use FromDevice and a DAG enabled version of libpcap to
read packets from the card. All that you need to do is to compile
libpcap with support for DAG:
./configure --with-dag=/path/to/dag/sdk --prefix=/path/to/libpcap-dag
make && make install

And then configure Click with the right libpcap:
export CPPFLAGS=-I/path/to/libpcap-dag/include
export LDFLAGS=-L/path/to/libpcap-dag/lib
./configure ...

Of course it is possible to write a new element that calls the DAG api
directly. However, is this going to make a substantial difference for
this application?
For the original application (dumping packets to disk), it is clear to
see the advantage of having the card using DMA transfer to transfer
groups of packets into memory and having the software to copying big
chunks of memory at a time into disk.
Instead, an hypothetical FromDAG element will read a group of packets
with DAG api and then push each packet individually.
So it apperas to me that you just avoid a couple of function calls into
libpcap which is already doing the above.

cheers


Beyers Cronje wrote:
> I do remember someone from Endace once posted on this list
> https://pdos.csail.mit.edu/pipermail/click/2004-November/003343.html so
> maybe that person can comment if he's still on th list ?
> 
> Now if only these types of cards were more affordable I'd happily write
> such an element.
> 
> The PCAP Express cards also look interesting and should be able to use
> FromDevice with PCAPX directly.
> http://www.pcapexpress.com/index.php/products
> 
> 
> 
> On Fri, Oct 31, 2008 at 9:23 PM, Eddie Kohler <kohler at cs.ucla.edu
> <mailto:kohler at cs.ucla.edu>> wrote:
> 
>     Hi Marco,
> 
>     As far as I know there is no element that speaks directly to Endace
>     cards.  We
>     do have elements that speak the DAG/CAP file format generated by
>     Endace cards
>     -- I'm guessing one could generalize those elements to speak to the
>     cards
>     directly.  I'd love to see such elements in the distribution.
> 
>     Any takers?
> 
>     Eddie
> 
> 
>     Marco Canini wrote:
> Hi Eddie,
> 
> are you aware of any FromDAG element?
> 
> I've a box that captures traffic with a DAG card. I can use libpcap to
> sniff packets but eventually it would be nice to have an element that
> uses the DAG api directly.
> 
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- --
Marco Canini
Ph.D. Candidate
Department of Communication, Computer and System Sciences
University of Genoa
Via all'Opera Pia 13
16145 Genoa Italy
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