Hi,

We are using NDIS MUX IM sample for our testing.

In that we are creating and sending some packet in ioctl
handling.

But we observed that, after sending that packet, we are
receiving same packet back in PtReceive call.
(some kind of LoopBack) . The packet is going on network
also..


What will cause of this???


Thanks in Advance,
nimeesh

Nmeesh,

What is your current packet filter set to?

Bryan S. Burgin
bburgin@microsoft.com

This posting is provided "AS IS" with no warranties, and confers no rights.

hi Bryan,

no filter as such ...

i'm receiving all packets in PtReceive().

But now checking for mac address and drop loopback packets.

This is the only way or there is some standard way to do
this..

nimeesh

To rephrase, what is your OID_GEN_CURRENT_PACKET_FILTER set to?

Bryan S. Burgin
bburgin@microsoft.com

This posting is provided "AS IS" with no warranties, and confers no rights.

[Re-posting my followup from "kernel-mode"]

IIRC, this is different in W2K and XP. In W2K you will receive the
send packet even if you set the NDIS_FLAGS_DONT_LOOPBACK flag in the
packet.

However, it all depends on the destination address in the packet's MAC
header. If the I/G (Individual/Group) bit is set (i.e. a multicast or
a broadcast), you are likely to see the same packet received. If the
I/G bit is clear then NDIS will still loop back the packet if the
destination address matches your OID_xxx_CURRENT_ADDRESS.

In order to suppress loopback on W2K set the undocumented
NDIS_FLAGS_SKIP_LOOPBACK flag. But do *not* set this flag in any other
environment, e.g. XP. This could lead to unpredicatble results. Check
the "NdisVersion" to be exactly 5.0 *and* the "Environment" to be
'NdisEnvironmentWindowsNt'. See the description of
NdisReadConfiguration() for details.

Stephan
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On Mon, 14 Jul 2003 21:42:05 -0700, "nimeesh"
<nimeesh@divinetaccess.com> wrote: