On Tue, 2006-08-29 at 10:54 +1000, Markus Buchhorn wrote: > Hi Chris > > At 09:55 AM 29/08/2006 +1000, Chris Kendrick wrote: > >How do I check if it is the local machine having packet loss rather than > >network packet loss? > > Rough rule of thumb - if you're seeing packet loss and if you're not using > more than 30% of the available bandwidth to your interface (just add all the > streams together), I'd be suspicious it was local. Check the CPU, if it's > more than 30% say, I'd be even more suspicious. Of course, if you have a 1G > interface to your machine and a 10M feed into your building I'd look into > that a bit more :-) > > Are your audio and video process running on the same machine?
Yes, at the moment I have my audio service running on my display machine, apparently audio doesn't use up much system resources. > > Ideally you want to get stats from your network switch and your network > interface, possibly via snmp, to see the true rates and compare them to what > the apps are saying. > > >I did try a different Virtual Venue, but upon looking at the bridge that > >is available for selection when on unicast at each VV I have since > >noticed that they both use the same bridge AGSC/Manchester. If it > >happens again I will try to set up a testing session with the AG Admin > >at the other end to try another bridge, unfortunately the people running > >the AG at 8am there time are not technicians so I couldn't check this > >straight away. > > Fair enough. It's certainly worth testing - some bridges seem to misbehave > after some period of uptime, or just for the fun of it <sigh>. > > >> I'd start with monitoring the traffic very carefully. Did vic show > >similar drops? You can watch its traffic graphs and generate a nice > >picture to take to your network folks. You can run things like iperf if > >you're really keen. > >> > > > >aahh, ok, I'll take that as, "Use iperf to take a look at network goings > >on" > > Not quite - it'll give you an idea of the end-to-end performance between an > iperf client and an iperf server. If you're running close to the iperf > suggested peak (for UDP) then I'd expect loss somewhere. The reasons for loss > though can be very diverse, from congestion to errors (dodgy cables) to > routing flaps to ... etc. Without a probe point at almost every hop it can be > very hard to diagnose. > > >Yes sorry, I forgot to mention that the picture when very blocky and > >choppy as well, when the audio suffered packet loss. > > Ok, so that is consistent. > > >VIC has traffic graphs? how do you view them? > > On the thumbnail view, pick a site and click on 'info' - that gives you a set > of metrics about that stream from that site. Click on one of the words to > get a strip chart of that metric (e.g. 'kilobits' can be good, though subject > to changes in the video content, but it gives you a good long-term view of > the rate. Loss shows up quite sharply, but it doesn't tell you where the loss > is). Ahh, thats nice, another diagnostic to go in my toolbox =) > > >Our bridge is on the same subnet as our AG Nodes. So if the AG node > >can't to multicast to the Bristol VV neither can our bridge. We are not > >on AARNET. We are on Grangenet. I don't know if Grangenet peers to > >JANET. But when I go to the Bristol VV I don't get any audio/video > >feeds if I don't switch to unicast. > > GrangeNet peers with with the international networks via AARNet (in Sydney), > which includes the international multicast feed. So I'm not totally sure why > you're having an issue. However, I've had similar problems with Oxford. > Interestingly very few problems with US sites, who should be on the same > path. I wonder if the new western route from AU to EU is causing us grief... > > Cheers, > Markus Thanks Markus, and others who have replied. The e-mails have given me a heap of great new Insight/Tools to be able to further diagnose AG connectivity issues with. Chris Kendrick VPAC > > > Markus Buchhorn, ANU Internet Futures |Ph: +61 2 61258810 > markus.buchh...@anu.edu.au |Fx: +61 2 61259805 > The Australian National University, Canberra 0200 |Mob: 0417 281429 >
