ng_fec and cisco 2931

David Gilbert dgilbert at
Mon Feb 28 16:11:28 GMT 2005

>>>>> "lister" == lister  <lister at> writes:

lister>  I have setup ng_fec on a machine with a quad ethernet NIC :

lister> de0: <Digital 21140A Fast Ethernet> port 0xd000-0xd07f mem

Our own testing with this card (not using fec ... just traffic on the
4 ports) has determined that it appears to have a 100 megabit limit to
the total of 4 ports on the card.  Now... this could be a FreeBSD
driver issue ... or a PCI bus issue, but in all our tests with several
motherboards and many versions of FreeBSD (from 3.2 or so through
about 4.5) we were never able to achieve more than 100 megabit on the
card in total.

Our application was an NFS server that had 100's of diskless nodes
running from it.  We suspected that this could be some interaction
between the speed of the disks (and their pci cost) and the card, so
we isolated the card by doing straight packet tests (no meaningful
data) and still found the card maxxing out at 100 megabit total over
the 4 ports.


|David Gilbert, Independent Contractor.       | Two things can only be     |
|Mail:       dave at                    |  equal if and only if they |
|                              |   are precisely opposite.  |

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