problem with internet speed due to packet drops in gateway/proxy

[anilonet]

Recently we are facing a problem with internet speed. During daytime speed will be very slow as low as 100kbps(as shown in speedtest.net).

We have 1Mbps Internet Leased Line (ILP).

When I use ping from a client machine or server itself it shows regular packet drops 10% normally and 20% worst.

We are using Fedora 7 as gateway which runs Iptables with NAT and Squid proxy.Another Linux machine runs a Samba server as domain controller.All the clients in are Windows XP Pro but laptops running XP Home,Vista are ther connecting thru a Wireless.
I made a settings change in gShield.conf and Squid.conf file so that now everybody has to use the proxy settings in browser.This is for http traffic only and other traffic(POP,SMTP,FTP,Torrent,HTTPS) is not affected by this proxy.

Same server runs a DNS service(named) also


Also we made some policy to regulate usage such as download,torrents etc

These measures improved the performance very well but still I can see 1-3% packet drops.This happens when internet traffic is more like active torrent download.Maximum simultaneous users will be <50.
This packet drop causes slow browsing speed as well as breakup Skype call,web conference etc

When there is 0% packet drops speed will be near 1MBps at any time independent of the no.of clients on network.


1)Is server is responsible for the packet loss .It is sure that no problem with ISP as I tested direct connection using laptop.Server uses 1GB RAM and FREE shows total 1025K used-1015K free-10K . This is always similar even when there is no packet drops
2)Is high data transfer makes the packet drops at server
3)Is WLAN Vista/XP Home clients causing disturbance

[johnwill]

If it's not the ISP, the other logical failure point is the server, since it handles all the traffic.

[anilonet]

Thanks for the support.

It is sure that ISP or the line have a problem as we changed the line also.

If we zeroing on the server what are the possible reasons or solutions to this problem.
I am upgrading the RAM to 4GB because free memory shown very low.
No configuration change was done in the recently before the problem started.
Server runs Apache,dhcpd,named,mysql,openvpn,knowledgetree services also other than Squid and Iptables/NAT but they are not resource intensive(not used much).
Thanks

[johnwill]

If it's the server, there could be any number of causes, it's virtually impossible to speculate from afar. You have a laundry list of stuff you're running that could cause problems.

[anilonet]

I tried pinging the default gateway of internet port 'eth0' for one minute as :
#ping -f xxx.xxx.xxx.xxx
13450 packets transmitted,13383 received,0% packet loss,time 60291ms

I disabled the LAN port 'eth1' and again pinged the default gateway for one minute:
#ping -f xxx.xxx.xxx.xxx
15263 packets transmitted,15262 packets received,0% loss, time 60660ms

Similar results got when same test is repeated .This is done when all the laundry services are still running.This matches with experience that when users on LAN are idle packet drops are few.
Is this infers that some client/setup on the LAN interfere with the packet drops on server?
Or the server cannot handle the traffic when both NIC are active ?

I connected another internet connection to a Netgear Wireless router and made as the default gateway.When I pinged ISP's DNS server using ping xxx.xxx.xxx.xxx -t option there is not a single packet drop observed eventhough both Wireless router and the clients are in the same network which contains Linux gateway server which had the reported problem