Skype consumptions, can anyone HELP?!?

[Twister]

Hi there,

I'm new to this all voip thing and am currently using Skype to talk to family overseas from Jhb, SA on a daily basis. I am absolutely shocked with the consumption I'm getting, a 30min call to a pc in Portugal chomped the best part of 150Mb (around 60Mb for upload and around 90Mb for download) , is this normal?

Can anyone help or maybe advise on other Voip providers that don't swallow your Mb at such a rate?

Would aprreciate any help ASAP!!!!

Thanks!

 

[Toitjie]

well i spoke 3 hours locally, and with vid streaming and it ddnt take as much

 

[bwana]

Hi there,

I'm new to this all voip thing and am currently using Skype to talk to family overseas from Jhb, SA on a daily basis. I am absolutely shocked with the consumption I'm getting, a 30min call to a pc in Portugal chomped the best part of 150Mb (around 60Mb for upload and around 90Mb for download) , is this normal?

No - are you using video?

 

[HavocXphere]

Should be 20 megs max for 30 mins....possibly more if your on a fat unshaped line.

I suspect you've become a supernode on skype. Did you fidget with the port forwarding/firewalling on your router?

 

[gmza]

That works out to 409kbit/s in the download direction which is much greater than the consumption required for a single Skype call. As somebody else mentioned, you may be trafficing other calls aside for just your own. That is the joy of using a peer-to-peer network like Skype rather then a client-server network! The idea is that everyone shares is making a much more scalable network, but it doesn't work so well in places where bandwidth is expensive!

A standard SIP provider using SIP with G.729 codec will use 10.5MB for a 30 minute call (about 5.25MB upload, 5.25MB download).

Swith Telecom's rate to Portugal (land-line) is 30c/min and they offer such a service. See: http://www.switchtel.co.za/index.php?nav=call_rates
Other local companies using similar technology include Vox Telecom. There are also various international companies offering SIP termination. Just ensure the codec in use is G.729 or similar low bit-rate codec.

 

[Yotch]

How much bandwidth does Skype use while I'm in a call?
Skype automatically selects the best codec depending on the connection between yourself and the person you are calling. On average, Skype uses between 3-16 kilobytes/sec depending on bandwidth available for other party, network conditions in between, callers CPU performance, etc.
Skype also uses "0-0.5 kilobytes/sec while idle".

http://mybroadband.co.za/vb/showthread.php?t=76304&highlight=Skype+bandwidth

Here are some bandwidth figures for the different codecs in use. BR = bit rate, NEB = nominal ethernet bandwidth. These figures are only for one direction. A value of twice the NEB would probably be a reasonable estimate. The type of ADSL encapsulation being used (PPPoE LLC) also introduces additional overheads of as much as 15-20%. Silence suppression should reduce the overall figure slightly.

Codec BR NEB
===== ====== =======
G.711 64 Kbps 87.2 Kbps
G.729 8 Kbps 31.2 Kbps
G.723.1 6.4 Kbps 21.9 Kbps
G.723.1 5.3 Kbps 20.8 Kbps
G.726 32 Kbps 55.2 Kbps
G.726 24 Kbps 47.2 Kbps
G.728 16 Kbps 31.5 Kbps
iLBC 15 Kbps 27.7 Kbps

A figure of 8 kilobytes per second is probably a reasonable estimate for the G.729 codec which is consistent with the figures mentioned above i.e. ~14 megabytes for a 30 minute call.

 

[.Froot.]

http://mybroadband.co.za/vb/showthread.php?t=76304&highlight=Skype+bandwidth

Here are some bandwidth figures for the different codecs in use. BR = bit rate, NEB = nominal ethernet bandwidth. These figures are only for one direction. A value of twice the NEB would probably be a reasonable estimate. The type of ADSL encapsulation being used (PPPoE LLC) also introduces additional overheads of as much as 15-20%. Silence suppression should reduce the overall figure slightly.

Codec BR NEB
===== ====== =======
G.711 64 Kbps 87.2 Kbps
G.729 8 Kbps 31.2 Kbps
G.723.1 6.4 Kbps 21.9 Kbps
G.723.1 5.3 Kbps 20.8 Kbps
G.726 32 Kbps 55.2 Kbps
G.726 24 Kbps 47.2 Kbps
G.728 16 Kbps 31.5 Kbps
iLBC 15 Kbps 27.7 Kbps

A figure of 8 kilobytes per second is probably a reasonable estimate for the G.729 codec which is consistent with the figures mentioned above i.e. ~14 megabytes for a 30 minute call.

Kbps is KILOBITS PER SECOND. not KiloBytes. Skype averages at ~8down+~3up (kilobytes per second)==64Kbps downstream and 24Kbps upstream. This makes 19.3Megs per 30min.

 

[gmza]

Further to the last post, for billing purposes, bandwidth will be monitored at the IP level. Most codecs use 50 packets per second and the IP/UDP headers are 40 bytes. That works out to 16kbit/s. G.723.1 and iLBC use 33.3 packets per second, meaning headers will take 10.7kbit/s (over and above the voip payload).

The figures quoted for nominal ethernet bandwidth are slightly high for BILLING purposes as they include ethernet overhead.

They are also slightly low for calculating the capacity used on ADSL as ADSL uses ATM on its back-end. ATM encapsulated data in lots of small frames. VoIP packets are small, but not that small, so you get huge inefficiency carrying VoIP over IP over ATM.

Eg. Let's look at a SIP/G.729 call:

VoIP payload: 8kbit/s (this is the actual voice)
IP headers: 16kbit/s (eish, tripling the bandwidth usage already)
Now, since each packet is 60 bytes and an ATM cell payload is 48 bytes, you need two ATM cells per packet. Yup, 96-60 = 36 bytes wasted. Not to mention the cell headers, 5 bytes each, making that 46 wasted bytes. This means that at ATM level, the usage is a whopping 42.4kbit/s!

People quote ~13% as the typical ATM (ADSL) overhead that you can strip off for IP. When encapsulating average or large size IP packets, this is correct. Theoretically, the most efficient you'll get is to use the entire ATM payload (48 bytes) for each ATM cell (53 bytes) and lose only the 5 bytes to headers. 5/53 = 9.4%, so that's the MINIMUM overhead.

A typical IP packet is around 500 bytes which means that it will fit in 12 ATM cells with an average of 50% of the last cell wasted. That works out to 13.2% overhead.

By comparison, a SIP/G.729 VoIP call would incur (42.4-24)/24 = 76.7% overhead when carried over ATM. Nasty!!!

The important thing to remember here is that the rate including ATM headers will give you an indication of how much of the capacity of your ADSL is consumped by a VoIP call (measured against the ADSL sync rate).

The IP rate, however, excluding ATM headers, will give you an indication of the amount of traffic you will be billed for.

 

[Tunasashimi]

Howsit guys... Didnt care much to read the technical verbal diahorrea above..

As a rule of thumb, Skype calls use 5KB/s: that is 300KB per minute, or 18MB per hour. (Double to ten-times that for Video, depending on the quality and framerate set). (PS That's 5 Kilobytes per second, multiply by ~10 to get Kilobits per second)

BUT... .. .. .. . . . .

The Skype protocol is quite interesting, and uses Peer-to-peer and clustering. If your internet connection is the fastest in your vicinity, it may select you to be a supernode - and then ROUTE OTHER PEOPLE's CALL INFO AND FILE TRANSFERS THROUGH YOUR INTERNET CONNECTION!!!!

So, how do you avoid that? Don't keep Skype running in the background. Only fire it up when you need to make calls.

Although, if you want to keep it running so you can have people calling you, get a fancy router that can do L7 Traffic Shaping and limit Skype to 64-256kbps.

But! What is really cool about Skype is the fact that it doesn't use any bandwidth when you talk to people on a LAN (or a suitably configured WAN - think WUGs or Wi-Fi networks)...

Some more sources of technical diahorrea of the cut-and-spam-a-thread variety:
http://www.guha.cc/saikat/pub/iptps06-skype/
http://forum.skype.com/index.php?showtopic=16251
http://forum.skype.com/index.php?showtopic=108446 - technical call details supposedly shows bandwidth use
http://forum.skype.com/index.php?showtopic=102128 - video call quality ranges use up to 500kbits/s or >30KB/s!!
http://forum.skype.com/index.php?showtopic=27132 - Network Administrator's guide to Skype - download it, read it, and correct my quacktic knowledge as recklessly divulged above.

 

[Twister]

Thanks for the reply! my apologies for taking this long to get back to you guys!

Only I have a webcam and I did use video in one occasion but that particular call I only switched the webcam on for about 5 minutes.

I'm not to clued up with this stuff so I'll try to explain how I'm using the net untill I get my own.

I'm running a cable from my mate's Telkom router who has a 384Kb ADSL line and a 2GB cap with m-web @ R219.00 (which we assume is unshaped). I didn't install any software, passwords, etc. I just ran the cable from the router to the back of my pc, went to "Network connections" - "LAN or High speed Internet" and switched on my "Local area connection" which shows the Firewall to be on and connects using the "NVIDIA nForce Networking Controller".

No idea if I'm making any sense at all but as thankfull as I am for the replies and information supplied I don't understand most of the lingo that is going on in the posts. i do understand that as I suspected the consumption is high but that's that.

Can anyone help me with settings or whatever to get normal consumptions?

One last thing, as I'm going to be getting my own line and provider, to run Skype you need an unshaped or does a shaped line do the job (I do not no the difference between the two) all I can say is that i use the net for web browsing, updating software, messenger, e-mails, the odd download and Voip services.

Excuse my ignorance but any help would be greatly appreciated!!!

Cheers guys!

 

[.Froot.]

Howsit guys... Didnt care much to read the technical verbal diahorrea above..

As a rule of thumb, Skype calls use 5KB/s: that is 300KB per minute, or 18MB per hour. (Double to ten-times that for Video, depending on the quality and framerate set). (PS That's 5 Kilobytes per second, multiply by ~10 to get Kilobits per second)

BUT... .. .. .. . . . .

The Skype protocol is quite interesting, and uses Peer-to-peer and clustering. If your internet connection is the fastest in your vicinity, it may select you to be a supernode - and then ROUTE OTHER PEOPLE's CALL INFO AND FILE TRANSFERS THROUGH YOUR INTERNET CONNECTION!!!!

So, how do you avoid that? Don't keep Skype running in the background. Only fire it up when you need to make calls.

Although, if you want to keep it running so you can have people calling you, get a fancy router that can do L7 Traffic Shaping and limit Skype to 64-256kbps.

But! What is really cool about Skype is the fact that it doesn't use any bandwidth when you talk to people on a LAN (or a suitably configured WAN - think WUGs or Wi-Fi networks)...


I have never managed to get Skype under 5KBps. Seriously. Because it isn't. It runs at 7-8KBPs downstream and 2-3 upstream-- >~10KB total per second-->35MByte per hour.

The reason that Skype doesn't use bandwidth across the network is because that is how it gets routed (A switch/ hub/ router will do this).

I've never found my Skype to use my network (ie transfer other's calls). It's not because I use a firewall either. I do have a very fast connection but this still does not happen...

 

[warwickw]

Hi there,

I'm new to this all voip thing and am currently using Skype to talk to family overseas from Jhb, SA on a daily basis. I am absolutely shocked with the consumption I'm getting, a 30min call to a pc in Portugal chomped the best part of 150Mb (around 60Mb for upload and around 90Mb for download) , is this normal?

Can anyone help or maybe advise on other Voip providers that don't swallow your Mb at such a rate?

Would aprreciate any help ASAP!!!!

Thanks!

Are you sure your PC wasn't doing a Windows Update at the same time.

The rates look horribly high.

 

[Syndyre]

If you want to block Skype from becoming a supernode, go here, its just a registry setting.

 

[Twister]

If you want to block Skype from becoming a supernode, go here, its just a registry setting.

Thanks for that link Syndyre! I downloaded it into the Skype folder in my programs and double clicked on it, it asked if I was sure and said yes, restarted the pc, did i do it right?

Ok so here's what I got out of a 29 minute call with about 3 minutes of video streaming from my side only on 320x240 resolution at 30fps: the Skype info box that comes on if you place the mouse over the contact your calling reads- for "OUT-UDP 69000 packets" and the "IN-UDP 102000 packets". But when I check the "Activity" on "Local area connection state" box I read "Sent packets 82.561" and "Received packets 122.231".

Can anyone from this bit of info tell me what's my actual consumption in Mb?

Thanks to you all for your input and my apologies for my pc illiteracy!!!

Good week to you all! CHEERS!