"Shaping" Conspiracy theories

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jake

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What if Telkom's shaping is also intended to make VOIP applications perform badly ?

Here are some tests I have performed, maybe others could do the same & we discuss the results.

1/listen to radio 702

http://www.antfarm.co.za/clients/702/702_16.asx
(cut & past into MS Media File>Open URL)

in MS Media player 9.0 open view->statistics->advanced

look at the protocol field, behind my fire wall I see "MMS TCP", however Media player's 1st choice is "MMS UDP" which is what I also see if I dial in OR use my router's DMZ IP address OR PPPOE.

In TCP mode it works perfectly, In UDP mode it stalls every other second. (you can force MSMP to to use TCP in options).

This indicates some form of shaping between TCP & UDP on Identical routes to the same server(antfarm is related to IS). UDP is the perferred carrier protocol for realtime stuff like streaming media & VOIP but is more problematic with fire walls.

2/ Using the www.skype.com VOIP system, which is the best VOIP system for traversing firewalls etc (everyone raves about its quality).

If I talk to a guy on a Telkom satelite Internet link it is perfect. If I talk to someone in Durban on a NON Telkom ADSL ISP, it is unusable, my overseas tests have been limited & results poor.
 
I don't agree with you on number one, it is probably more a result of the inherent behaviour of the respective protocols. TCP ensures that all packets are received whereas UDP is "fire and forget", so it's very possible that packets are getting lost or dropped.

I can't comment on your specific setup using Skype however I use Skype over ISDN to talk to friends in the UK and it works perfectly most times. At the moment there is also no such thing as a "non-Telkom ADSL ISP" (apart from DataPro) as all ISPs merely resell Telkom ADSL packages.
 
Are you saying you tested it & do not see what I'm seeing (as far as I'm aware there is no shaping on ISDN) ? - that was the intention of the post, not to start some techie mumbo jumbo debate.

If you are saying that TCP is a better protocol than UDP - you are wrong, this is not a file download, if I lose a packet, I certainly do no want to hear it out of time sync ! I want the player to play the next packet asap. That is why MSMP perfers UDP. It is more difficult for a NAT gateway (firewall) to match an incoming UDP packet to a internally originated connection.

It has been stated many times on this forum that ISDN connections seem to perform better than ADSL for latency sensitive applications like VOIP, If they are shaping it the latencies could be very random. That is the topic of this discussion, anyone care to do some tests to concur / or flame me ? on both ISDN & ADSL & ADSL UNSHAPED
 
I didn't say TCP was better, just commented on the behaviour of each protocol and why UDP may not be working correctly. In most instances UDP is a "better" protocol for streaming as it has less overhead and it doesn't matter (in theory) if some packets are dropped.

With TCP you will not hear a stream "out of time sync" unless it stops to buffer information and this only happens when you have insufficient bandwidth, in which case UDP will suffer too. I don't think shaping on ADSL would affect a local audio stream that much be it UDP or TCP.

btw the above address works 100% for me.
 
I haven't had any problems with VoIP but I know that if Telkom decides to make it fail, they could... It would be detrimental to their business as it would irritate customers already on the fringe who would easily drop the service when it becomes too much effort...

Regards
Antowan

### What we need in South Africa is cheap 24/7, always on Internet for under R300 a month. ###
 
i don't think they can realy shape VoIP. i know that you can shape a port, but i don't think you can shape a *packet type*. they will have to inspect each packet to figure out what the 0's and 1's most likely is and then shape... don't think that with today's processing power that will be possible (yet).

i haven't used VoIP in the last couple of years, but I would think that you could choose a port to communicate on... like P2P. btw, you can get incredible speeds on P2P if you use port 80,20 or 25 (web, ftp, smtp).
 
You can shape packets based on protocol, however Telkom merely employs "poor man's" bandwidth management (i.e. shape ports) knowing that the majority of people don't know how to circumvent it. They also have no need to prevent the few people that do get around this from doing so as there is the 3 gig cap... those people just reach their cap faster [;)]
 
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