[LARTC] problem in speeds [Message from superlinux]

[Rani Ahmed]

i am assigned a network to  replace its "Windows server with ISA caching 
proxy" with another "debian linux with squid proxy" with both  "linux" 
and "ISA" are completely differnet boxes. i am using  linux 2.6 kernel 
since the linux server has SATA hard disks .

the network has downlink with a penta at net DVB card for down-link ; then 
it's connected to the ISA server which   distributes the connections to 
3 other networks. the UP-Link is routed thru a cisco router which is 
connected with an ISP selling the network owners  the bandwith of 
512Kbit/sec DownLink and 128kbps UPLink. this is a sketch  which might  
can help:


                                                                         
                                                downlink          LAN1 
                                                                         
                                                 ----->                 
/\   
Internet  >>> PENTA at NET on Windows server ] >>> [ISA proxy server on 
Windows] ======>>LAN2
                                                                        
                        ||                                               
   \/  
                                                                         
                       ||                                              
LAN3        
               Internet <<<<ISP<<<UPlink <<<<Cisco router||
                                                                         
                          
what i have done on linux is just a simple NAT and a redirect to Squid 
to force transparent cache so the user does not have to configure his 
browser.

The Problem:
==========

I did not do any shaping, even on squid no shaping, and all i get using 
the NETSPEED GNOME plugin on the Internet side is 16 Kbytes per sec up 
and 32Kbytes/sec on the Local side as total speed of the whole 3 
networks.  and as you should have noticed, my Linux box should work as a 
water hause or pipe and has no real effect on the bandwidth.

if i returned back the windows ISA box the speed goes normally at its 
52kbyte/sec.

so what is happening FOR GOD'S SAKE!!???

in addition , after all that,  i thought it was slow because of the RCV 
and SEND buffers settings in the kernel an the TTL=64. so set RCV and 
SEND as twice the kernel's default on /etc/sysctl.conf as:

net.core.rmem_default = 262140
net.core.wmem_default = 262140
net.core.rmem_max = 262140
net.core.wmem_max = 262140

the RESULT IS THE SAME!!!

so what is happening FOR GOD'S SAKE!!???