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Hello,<BR>
<BR>
I have a linux box (2.6.19) with two NICs (eth0 and eth1), setup as a bridge.<BR>
<BR>
The bridge sits between a server machine and a client machine (via cross-over cables).<BR>
<BR>
The server machine is connected to eth0 NIC.<BR>
<BR>
The client machine is connected to eth1 NIC.<BR>
<BR>
I am sending raw TCP data to the client machine from the server machine. This means data enters the bridge via eth0, and is bridged through to eth1, where it leaves the linux box and arrives at the client machine.<BR>
<BR>
The forward channel is therefore all packets travelling from the server to the client. The reverse channel is obviously all the acknowledgements flowing back to the server.<BR>
<BR>
I am using Netem to add loss rates to eth0 and eth1, either together or independently.<BR>
<BR>
I have noticed something very interesting.<BR>
<BR>
When adding a very high packet loss rate to eth0 (i.e. tc qdisc add dev eth0 root netem loss 40%) and then running my raw TCP data throughput tests, i get full throughput results, exactly as i do for when there are is no qdisc attached to eth0. In fact, for loss rates ranging from 0% to 50% my results are unchanged. Basically, i do not think Netem is dropping packets in the forward channel direction, which is what I am trying to emulate.<BR>
<BR>
Looking at the structure of how netem is implemented, by attaching a qdisc to eth0, all packets entering eth0 from the server should be subjected to any rule applied to eth0.<BR>
<BR>
Is anybody able to explain what is happening here?<BR>
<BR>
Thanks in advance.<BR>
<BR>
Ritesh<BR>
<BR>
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<TT><FONT COLOR="#0000ff">Adaptive Communications Networks Research Group</FONT></TT><BR>
<TT><FONT COLOR="#0000ff">Electronic Engineering Dept.</FONT></TT><BR>
<TT><FONT COLOR="#0000ff">Aston University</FONT></TT><BR>
<TT><FONT COLOR="#0000ff">Birmingham</FONT></TT><BR>
<TT><FONT COLOR="#0000ff">B7 4ET</FONT></TT><BR>
<BR>
<TT><FONT COLOR="#0000ff">t: +44</FONT></TT><TT><FONT COLOR="#0000ff"><FONT SIZE="1"> </FONT></FONT></TT><TT><FONT COLOR="#0000ff">(0)7732 069 667</FONT></TT><BR>
<TT><FONT COLOR="#0000ff">e: taankr@aston.ac.uk</FONT></TT><BR>
<TT><FONT COLOR="#0000ff">w: <A HREF="http://www-users.aston.ac.uk/~taankr/">www-users.aston.ac.uk/~taankr</A></FONT></TT>
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