On Tue, Apr 19, 2011 at 7:55 AM, Girish Venkatachalam <[email protected]> wrote: > On Mon, Apr 18, 2011 at 7:41 PM, Preetish <[email protected]> wrote: >> Hello Everybody >> >> I am not sure if this is the correct forum to discuss this so kindly >> ignore this email if you find the topic irrelevant for this forum. > > Such long mails are a bore. It is like a novel. ;) > > Please write short sweet mails. > >> Recently we have started facing issue in our network where in if we >> initiate a Video Conference ( we use Video Nation Life Size VC >> equipment ) we see packet loss which goes upto 40% and jitters which >> goes upto 100ms . This packet loss is only on incoming packets. So the >> voice and video quality is very bad at our end however the person at >> the other end is able to see and hear us very clearly. If we look at >> the VC statistics, we can see that we are uploading at around 1 mbps >> however the download starts at 1 mbps but then drops down to 100kbps >> within seconds . Same is the case with skype calls . > > Good. ;) > > Normally download speeds are higher. > >> Now one of the reasons I am posting over here is that all our network >> traffic goes via a debian box ( 5.0.4 ) which acts as the firewall. >> The cpu utilization on the firewall is not high at all. This debian >> box also acts as a vpn server and we have two VPN tunnel to connect to >> our office in the UK . Also we use quagga ( ofpfd ) to route traffic >> over the tunnels. Also I have checked statistics ( ethtool -S eth1 ) >> of eth1 ( which is our internet link ) and it shows no error either on >> rx or tx . All our internal network are on various vlans on eth2 and >> there are no errors on it too. > > Good. > >> We have reported this issue to our ISP and they changed our route a >> couple of times ( even the reverse route was changed ) however it did >> not resolve the issue. Finally we bypassed our firewall and put the VC >> equipment on a public IP ( its on a different subnet than our firewall >> ) and we are not facing the issue any more ( I still have to check >> which route it follows to the Video Nation gateway and compare it with >> the route our firewall follows ) . > > Okay. > >> Now I know that there has been no change in our network which could >> have caused this issue. However now the ISP says that the issue might >> be because of our firewall . > > Quite possible. > >> Can someone let me know if there are any tools which can help me >> troubleshoot this issue. Something that can let me know the point at >> which there are packet loss. Also please let me know if I should be >> looking at . > > There is not enough information in this mail albeit long. > > And this is a complex issue. > > Some ways to attack this are: > > 1) Try turning off connection tracking and other stuff in the Debian > box and see > how the network performs
Sorry couldn't provide much information. Was trying to keep the email short ( I guess failed in that too :( ) . Well, we basically shut down all the services which this box runs ( except VPN, quagga, iptables ) however it did not resolve the issue. I have enabled sysstat on the system and will be monitoring it . > > 2) Try a simple command line wget or something and find out what is > happening. > We do not have any issue with downloads, the problem is with the incoming UDP packets ( voice and video ). I downloaded f14 iso yesterday and was getting a speed of 1 mbps . > 3) Monitor the bandwidth in the Debian box and afterwards. Find out if > something >goes wrong in between > Have installed ntop to monitor eth1 . > There are 100 other ideas I can give. > > But you have to do it. Any number ideas are most welcome . > -Girish > > > -- > G3 Tech > Networking appliance company > web: http://g3tech.in mail: [email protected] > _______________________________________________ > ILUGC Mailing List: > http://www.ae.iitm.ac.in/mailman/listinfo/ilugc > _______________________________________________ ILUGC Mailing List: http://www.ae.iitm.ac.in/mailman/listinfo/ilugc
