On 2009-12-09, at 18:28:29, Lewis G Rosenthal wrote:
>On 12/09/09 05:35 pm, Doug Bissett thus wrote :
>> On 2009-12-09, at 14:01:33, Lewis G Rosenthal wrote:
>>> I'll have to fashion myself a CAT-6 crossover to eliminate the
>>> switch from the equation.)
>> Most modern switches, and NICs, will automatically reverse the wiring,
>> if they think you might be using the wrong cable. Just try a normal
>Indeed, I thought of the auto-sensing circuitry, but don't know if the
>T43 or the new Intel chip (still trying to get GenMAC to work with it) -
>an 82567LF-2 - do auto-sense. The switch surely does, which is why I no
>longer stock crossover cables. :-)
I did my tests with a standard cable (probably CAT5) that is about 5
feet long. No trouble with not using a crossover cable.
>>> Has anyone else seen this type of performance hit cuased by the TAP driver?
>> No, but my switch, and router, only run at 100 Mbs, so I may not have
>> noticed a speed reduction. I will see if I can hook it direct from my
>> desktop to my T43, and see what happens (may be tomorrow, before I get
>> a chance).
>Thanks. I'm going to test on a couple other networks and systems
>available to me, as well. I, too, am normally sitting behind a 100Mbps
>secondary switch on this segment of the LAN or going wireless. However,
>the native B57 NDIS2 driver dropped off to under 500bps (that's bits,
>not Bytes!) vs GenMAC running the NDIS5 driver (without IJFW and IPX on
>While this thread doesn't necessarily deal with virtualization per se,
>it is surely of impact to those of us using VBox as host, as it is a
>major pain to have to reboot just to get networking going in the guest
Okay, first some information:
Asus M3A78-EM motherboard, using GENMAC with a Realtek 8168 NIC
IBM ThinkPad T43 (1871-W8M), using GENMAC with a Broadcom NIC
14E4:167D. This machine also has an Intel wireless 8086:4224, which
was radio off for the testing.
Both systems are running eCS 2.0 Silver, using NETBIOS over TCP/IP. The
T43 doesn't have the TAP driver installed. The M3A78-EM did not have
VBOX installed when I started, and the T43 has never had it installed.
Both systems also have Virtual PC installed, with the bridge driver. I
never actually ran VBOX on the M3A78-EM, before doing the tests. I am
PROTOCOL.INI on the M3A78-EM, after adding the TAP driver (I forgot to
copy it before adding it, but that is probably not relevant):
For some reason, UDP seems to have a problem, so I think you can
discount what that test says, in both cases.
The really interesting numbers are in TCP, and NETBIOS, with and
without the TAP driver installed. Sending seems to be limited to what I
see with my 100 Mbs hub in the network. With a direct connection, and
no TAP driver, send and receive seem to be about the same. The
interesting thing is that receiving doesn't seem to be affected by
whatever is slowing down sending.
As an aside, I discovered that the MPTS in eCS 2.0 Silver has added a
feature to install LLAeCS.EXE into \MPTN\BIN\MPTSTART.CMD, every time
it runs (even if you don't change anything). This took me on a wild
goose chase for a while, since LLAeCS.EXE hangs at boot, unless I start
it much later than in MPTSTART.CMD.
This is somewhat limited testing, but I think that it shows that the
TAP driver does limit send speed to something near 100 Mbs, even when
using a gigabit NIC. In different configurations, the results could be
I never tried wireless, but I will do that, when I find some time to
play with it again.
From the eComStation of Doug Bissett
dougb007 at telus.net
... See the Future; See eComStation. Be the Future; Run eComStation.