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Home > Archive > Voice Over IP in UK > April 2006 > skype broadband usage?
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skype broadband usage?
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| My brother has just joined up to Skype and I might consider joining myself.
Am wondering about what sort of bandwidth voip uses generally?
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| hairydog@despammed.com 2006-04-24, 7:56 am |
| On Sat, 22 Apr 2006 15:06:12 +0100, "Beck" <beck@photoscene.invalid>
wrote:
>My brother has just joined up to Skype and I might consider joining myself.
>Am wondering about what sort of bandwidth voip uses generally?
Two different questions.
VOIP uses around 80kb/sec each way when in a call, and almost none the
rest of the time.
Skype is a peer-peer application, and if you have an always-on
connection it can use, it may well pass other people's calls via your
connection to get through firewalls and NAT routers. So it may pass
traffic when you are not making calls. That means there is no way to
know how much data will be transferred.
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| Alan J. Flavell 2006-04-24, 7:56 am |
| On Sat, 22 Apr 2006, hairydog@despammed.com wrote:
> Skype is a peer-peer application, and if you have an always-on
> connection it can use, it may well pass other people's calls via your
> connection to get through firewalls and NAT routers.
I don't use Skype, but I have read the protocol study at
http://www.cs.columbia.edu/techreports/cucs-039-04.pdf
> So it may pass traffic when you are not making calls.
yes, if you're selected as a supernode, apparently.
In section 1 it says that "Any node with a public IP address[...]
is a candidate to become a super node".
I had read that as implying that if you were behind a NAT router, you
wouldn't be elegible to become a supernode.
However, in 2.6 it says [...]a Skype client cannot prevent itself
from becoming a super node.
> That means there is no way to know how much data will be
> transferred.
Indeed this would be a risk for anyone who pays for data volume, or
gets capped if they exceed some limit. Maybe(?) what the sentence in
section 2.6 means is that the S/C software itself has no option to
disable becoming a supernode. But if one can manipulate one's network
situation - by NAT gateway or firewall - maybe it's possible to defeat
this from happening?
I don't really know - just putting it up for discussion...
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| Paul Cupis 2006-04-24, 7:56 am |
| hairydog@despammed.com wrote:
> VOIP uses around 80kb/sec each way when in a call, and almost none the
> rest of the time.
I think that the bandwidth usage is dependant at least partly on the
codec being used.
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| Ivor Jones 2006-04-24, 7:56 am |
|
"Paul Cupis" <paul@cupis.co.uk> wrote in message
news:e2egi4$1bl2$1@custnews.inweb.co.uk
> hairydog@despammed.com wrote:
>
> I think that the bandwidth usage is dependant at least
> partly on the codec being used.
True, but that figure assumes the use of G711 which is probably the most
commonly used one.
Ivor
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| Paul Cupis 2006-04-24, 7:56 am |
| Ivor Jones wrote:
> [G711] is probably the most commonly used [VoIP protocol]
Do you have any data to back this up, please?
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| Nho Whei 2006-04-24, 7:56 am |
| On Sat, 22 Apr 2006 18:45:29 +0100, "Alan J. Flavell"
<flavell@physics.gla.ac.uk> wrote:
>On Sat, 22 Apr 2006, hairydog@despammed.com wrote:
>
>
>I don't use Skype, but I have read the protocol study at
>http://www.cs.columbia.edu/techreports/cucs-039-04.pdf
>
>
>yes, if you're selected as a supernode, apparently.
>
>In section 1 it says that "Any node with a public IP address[...]
>is a candidate to become a super node".
>
>I had read that as implying that if you were behind a NAT router, you
>wouldn't be elegible to become a supernode.
>
>However, in 2.6 it says [...]a Skype client cannot prevent itself
>from becoming a super node.
>
>
>Indeed this would be a risk for anyone who pays for data volume, or
>gets capped if they exceed some limit. Maybe(?) what the sentence in
>section 2.6 means is that the S/C software itself has no option to
>disable becoming a supernode. But if one can manipulate one's network
>situation - by NAT gateway or firewall - maybe it's possible to defeat
>this from happening?
>
>I don't really know - just putting it up for discussion...
Hmmm ... a tad disconcerting, this aspect of Skype. In the hope of
limiting such usage, I've unticked Options/Connection/Use port 80 &
443. Not sure if it really helps though. The other measures I take are
probably more certain of success. I don't auto start Skype. I fire it
up only when I need to use it, quitting it when done, and since I tend
to only use Skypeout, not being online at other times isn't a problem
for me.
I do this only cause I regularly burst my monthly datacap. Otherwise I
wouldn't bother.
| |
| Andrew Gabriel 2006-04-24, 7:56 am |
| In article <Pine.LNX.4.62.0604221826450.12517@ppepc70.ph.gla.ac.uk>,
"Alan J. Flavell" <flavell@physics.gla.ac.uk> writes:
> On Sat, 22 Apr 2006, hairydog@despammed.com wrote:
>
>
> I don't use Skype, but I have read the protocol study at
> http://www.cs.columbia.edu/techreports/cucs-039-04.pdf
>
>
> yes, if you're selected as a supernode, apparently.
>
> In section 1 it says that "Any node with a public IP address[...]
> is a candidate to become a super node".
IME, you become a supernode in well under a minute of going online.
In my observing, you _always_ become a supernode.
> I had read that as implying that if you were behind a NAT router, you
> wouldn't be elegible to become a supernode.
>
>
> Indeed this would be a risk for anyone who pays for data volume, or
> gets capped if they exceed some limit. Maybe(?) what the sentence in
> section 2.6 means is that the S/C software itself has no option to
> disable becoming a supernode. But if one can manipulate one's network
> situation - by NAT gateway or firewall - maybe it's possible to defeat
> this from happening?
>
> I don't really know - just putting it up for discussion...
I setup my parents' home network. They have real IP addresses
(the family's SIP and STUN servers are on their line). When a
visitor with Skype turned up, their laptop (with Skype installed
but not being used) rapidly started burning up the ADSL bandwidth
(I suspect it was using all the upstream bandwidth). Initially
I thought it was a virus -- I could see the laptop making TCP
connections all around the world, and firing off lots of UDP.
I changed the DHCP server to hand out private network addresses
and the problem was solved. Then I realised it was Skype.
--
Andrew Gabriel
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| Ivor Jones 2006-04-24, 7:56 am |
|
"Paul Cupis" <paul@cupis.co.uk> wrote in message
news:e2egrm$1bl2$3@custnews.inweb.co.uk
> Ivor Jones wrote:
>
> Do you have any data to back this up, please?
Other than it's been the default setting in every ATA I've ever used, no.
But I'd guess it's true, I'd guess most novice users wouldn't tinker. I
did say "probably" ;-)
Ivor
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|
| hairydog@despammed.com wrote:
> On Sat, 22 Apr 2006 15:06:12 +0100, "Beck" <beck@photoscene.invalid>
> wrote:
>
>
> Two different questions.
>
> VOIP uses around 80kb/sec each way when in a call, and almost none the
> rest of the time.
>
> Skype is a peer-peer application, and if you have an always-on
> connection it can use, it may well pass other people's calls via your
> connection to get through firewalls and NAT routers. So it may pass
> traffic when you are not making calls. That means there is no way to
> know how much data will be transferred.
Thanks for the information.
Taking a particular company out of the equation like Skype, is VOIP free
between VOIP users generally?
| |
|
| Andrew Gabriel wrote:
> In article <Pine.LNX.4.62.0604221826450.12517@ppepc70.ph.gla.ac.uk>,
> "Alan J. Flavell" <flavell@physics.gla.ac.uk> writes:
>
> IME, you become a supernode in well under a minute of going online.
> In my observing, you _always_ become a supernode.
>
>
> I setup my parents' home network. They have real IP addresses
> (the family's SIP and STUN servers are on their line). When a
> visitor with Skype turned up, their laptop (with Skype installed
> but not being used) rapidly started burning up the ADSL bandwidth
> (I suspect it was using all the upstream bandwidth). Initially
> I thought it was a virus -- I could see the laptop making TCP
> connections all around the world, and firing off lots of UDP.
> I changed the DHCP server to hand out private network addresses
> and the problem was solved. Then I realised it was Skype.
I don't see how this could have helped. Your visitor should still have been
able to use the Internet of course and Skype would still have been useable.
From what I've read it's (by design) very difficult to prevent Skype
working, except locally, I think I've read someone that it's possible by
blocking an initial call to a particular ip address but AFAICT the only way
is by packet inspection on the firewall.
| |
| Andrew Gabriel 2006-04-24, 7:56 am |
| In article <4b0insFv36edU1@individual.net>,
"J C" <jasee@btinternet.com> writes:
>
> I don't see how this could have helped. Your visitor should still have been
> able to use the Internet of course and Skype would still have been useable.
It was. The only difference was that buy giving him a NAT'ed
private network address, the PC stopped becoming a Skype
supernode, and relaying other peoples' calls (and using up
a large chunk of the ADSL bandwidth).
> From what I've read it's (by design) very difficult to prevent Skype
> working, except locally, I think I've read someone that it's possible by
> blocking an initial call to a particular ip address but AFAICT the only way
> is by packet inspection on the firewall.
I wasn't trying to stop Skype working -- some visitors need
to use it to keep in touch with relatives abroad. I was just
trying to stop it being used by other people too. That ADSL
line has a low cap on it, reflecting my parents' low usage,
but if it sat there for a few days running as a Skype
supernode, this would have exhausted the usage on it, and
it could have easily happened without me noticing.
--
Andrew Gabriel
| |
|
| Andrew Gabriel wrote:
> In article <4b0insFv36edU1@individual.net>,
> "J C" <jasee@btinternet.com> writes:
> I wasn't trying to stop Skype working -- some visitors need
> to use it to keep in touch with relatives abroad. I was just
> trying to stop it being used by other people too. That ADSL
> line has a low cap on it, reflecting my parents' low usage,
> but if it sat there for a few days running as a Skype
> supernode, this would have exhausted the usage on it, and
> it could have easily happened without me noticing.
I didn't know it was possible to stop it working in supernode mode, not an
expert on skype but I understand it (as well) it can and often does work in
that way whether you want it to or not. I can't see the difference between
manually handing out ip addresses and letting dhcp hand them out (from
Skypes point of view).
| |
| Andrew Gabriel 2006-04-24, 7:56 am |
| In article <4b18vhFtvoo9U1@individual.net>,
"J C" <jasee@btinternet.com> writes:
>
> I didn't know it was possible to stop it working in supernode mode, not an
> expert on skype but I understand it (as well) it can and often does work in
> that way whether you want it to or not. I can't see the difference between
> manually handing out ip addresses and letting dhcp hand them out (from
> Skypes point of view).
Sorry, nothing to do with DHCP -- that was being use in both cases.
However, it was originally handing out real IP addresses, and I
changed it so it was handing out private network addresses, and
that stopped the laptop becoming a supernode.
--
Andrew Gabriel
| |
| hairydog@despammed.com 2006-04-24, 7:56 am |
| On Sun, 23 Apr 2006 04:38:58 +0100, "Beck" <beck@photoscene.invalid>
wrote:
>Taking a particular company out of the equation like Skype, is VOIP free
>between VOIP users generally?
Yes, it can be, but no it usually isn't. I know a few people who use
VOIP and I could call them free by "dialling" their VOIP address or
IP, but I can't be bothered, and I dial their normal VOIP phone
number.
In theory that would cost money, but I use voip.co.uk so the call is
2p weekday peak time, and free at all other times. Not worth faffing
to save tuppence.
If there is someone you call regularly over VOIP it might be
worthwhile to do it the free way.
| |
| Ivor Jones 2006-04-24, 7:56 am |
|
"Beck" <beck@photoscene.invalid> wrote in message
news:444af6d5$0$2532$ed2619ec@ptn-nntp-reader02.plus.net
[snip]
> Thanks for the information.
> Taking a particular company out of the equation like
> Skype, is VOIP free between VOIP users generally?
As long as they are using the same provider or there is a peering
agreement in place between the relevant providers, yes. Or if you can dial
using IP addresses or the full SIP address (1234567@sipprovider.com or
whatever) then it should also work.
If you dial on a normal phone using an assigned PSTN number then if there
is no peering agreement it will (probably) be charged.
Ivor
| |
| datemas 2006-04-24, 7:56 am |
| Hi Beck
On calls about 1mb per minute- I have satellite capped at 128mb upload per
month and had to stop using it- try a google search for Netmeter- install
and check out for yourself.
"Beck" <beck@photoscene.invalid> wrote in message
news:444a3865$0$2527$ed2619ec@ptn-nntp-reader02.plus.net...
> My brother has just joined up to Skype and I might consider joining
> myself.
> Am wondering about what sort of bandwidth voip uses generally?
>
| |
| Andy Furniss 2006-04-24, 7:56 am |
| hairydog@despammed.com wrote:
>
> VOIP uses around 80kb/sec each way when in a call, and almost none the
> rest of the time.
Assuming that's at IP level and 50 pps then it will use 106kbit on a dsl
line. I am not saying you will be charged at that rate - I don't know
what level ISPs bill at, but it will use that much out of your
288/448kbit showtime rate.
Andy.
| |
| Andy Furniss 2006-04-27, 6:46 am |
| Peter Corlett wrote:
> Andy Furniss <firstname.lastname@dsl.pipex.com> wrote:
> [...]
>
>
>
> Metering of Internet traffic is normally done at the IP layer because that's
> what networking hardware tends to count.
>
Maybe, maybe not with dsl, and it may vary from ISP to ISP depending on
what sort of BT central they have. I'll be on a metered max soon so will
have more of a clue for my future ISP. I have read posts from plusnet
support that said it wasn't just IP.
Andy.
| |
|
| Beck wrote:
> My brother has just joined up to Skype and I might consider joining myself.
> Am wondering about what sort of bandwidth voip uses generally?
>
>
Skype uses about 5kbytes/sec.
| |
|
| JW wrote:
> Beck wrote:
>
> Skype uses about 5kbytes/sec.
Surely Skype useage depends on whether it becomes a Supernode, if it does
and the router (of instance) allows it, from what I've read of the ports it
uses, it's almost impossible to stop with a coventional adsl router, spi
won't help (quite the reverse), without totally closing the network for
other applications.
If it does then useage could be up to the full bandwidth? (Apparently it's
'selfish' in that way)
| |
|
| J C wrote:
> JW wrote:
>
>
>
> Surely Skype useage depends on whether it becomes a Supernode, if it does
> and the router (of instance) allows it, from what I've read of the ports it
> uses, it's almost impossible to stop with a coventional adsl router, spi
> won't help (quite the reverse), without totally closing the network for
> other applications.
>
> If it does then useage could be up to the full bandwidth? (Apparently it's
> 'selfish' in that way)
>
>
That's the figure I measured from my PAYG stats and Skype
call durations. That figure was also obtained in the
Columbia tests. I expect it would increase if you used the
optional video component or of course file transfer (though
I have found that desperately slow). I would have noticed
any excessive use, but then I don't usually leave the client
running when not in use.
It seems to me there's a lot of FUD surrounding this
Supernode aspect, put out by the many vested interests
opposing Skype and aimed at network managers who naturally
suspect any application they can't easily control.
According to a Skype staff member, "A supernode will use
approximately a tenth of the bandwidth of a user listening
to radio on the internet." I found another source which had
measured supernode bandwidth and found it was very low most
of the time.
I would guess that your probably need a lot of bandwidth to
begin with for Supernode status, as well as IP addresses
visible to the world (not behind a NAT Router). Is it
really likely to be a problem for a typical home user?
| |
|
| JW wrote:
> J C wrote:
>
> It seems to me there's a lot of FUD surrounding this
> Supernode aspect, put out by the many vested interests
> opposing Skype and aimed at network managers who naturally
> suspect any application they can't easily control.
It seems sensible, if you can't control it, because you can't simply block a
few ports (because those ports are used by other applications as well) and
so you can't, without detailed packet inspection, determine how much
bandwidth it _is_ actually using.
Those whose vested interest is to support Skype would naturally downplay
ordinary users possibilty of being supernoded (a relay host). Don't forget
the developers of Skype first developed Kazaa. where no such distinction is
made between users
> I would guess that your probably need a lot of bandwidth to
> begin with for Supernode status, as well as IP addresses
> visible to the world (not behind a NAT Router). Is it
> really likely to be a problem for a typical home user?
Don't know, don't use Skype, but I don't see why it should matter if the
Skype machine is natted, from the internet side he looks as if he has the
isps asigned ip address, just as if you go anywhere with any machine behind
a nat router for instance www.grc.com it will see the same ip address for
all machines. So it's irrelevant, surely.
| |
|
| Andy Furniss wrote:
> Peter Corlett wrote:
[vbcol=seagreen]
> Maybe, maybe not with dsl, and it may vary from ISP to ISP depending on
> what sort of BT central they have. I'll be on a metered max soon so will
> have more of a clue for my future ISP. I have read posts from plusnet
> support that said it wasn't just IP.
So if it wasn't just IP, what was it? ATM cells?
--
<http://ale.cx/> (AIM:troffasky) (gebssnfxl@ubgznvy.pbz)
22:52:31 up 2 days, 23:33, 3 users, load average: 0.01, 0.00, 0.00
This is my BOOOOOOOOOOOOOOOOOOOOOMSTICK
| |
|
| J C wrote:
> JW wrote:
>
>
>
> It seems sensible, if you can't control it, because you can't simply block a
> few ports (because those ports are used by other applications as well) and
> so you can't, without detailed packet inspection, determine how much
> bandwidth it _is_ actually using.
> Those whose vested interest is to support Skype would naturally downplay
> ordinary users possibilty of being supernoded (a relay host). Don't forget
> the developers of Skype first developed Kazaa. where no such distinction is
> made between users
>
>
>
>
> Don't know, don't use Skype, but I don't see why it should matter if the
> Skype machine is natted, from the internet side he looks as if he has the
> isps asigned ip address, just as if you go anywhere with any machine behind
> a nat router for instance www.grc.com it will see the same ip address for
> all machines. So it's irrelevant, surely.
>
>
Here's what Skype has to say about it:
".. a Skype client that is unable to receive inbound network
connections (such as a user behind a NAT or firewall) will
never become eligible to become a supernode nor will it
ever be asked to relay a third party’s traffic."
[Guide for Network Admins]
Contrary to my guess above, I read that the typical ADSL
upstream bandwidth may be enough for supernode operation.
However, the client need to be online over a long period, so
a machine that is switched off frequently will never become
a supernode. It doesn't seem difficult for home users to
avoid this, if they want to. Corporate networks may be a
different matter.
| |
| Andy Furniss 2006-04-27, 6:46 am |
| alexd wrote:
> Andy Furniss wrote:
>
>
>
>
>
>
>
>
> So if it wasn't just IP, what was it? ATM cells?
>
He didn't specify IIRC - just said there were more overheads.
I don't think it will be at ATM level for an ipstream ISP.
Looking at sin 412 which you can get from www.sinet.bt.com, it seems
that for a 622 meg L2TP central (and there are other sorts) the minimum
MTU the ISP can run on their interface to BT is 1542.
I think it's your IP in PPP in L2TP in IP/UDP - but whatever the detail,
if they do account for traffic size as sent through the central, then it
looks worse for voip than bulk in % terms. 1500 + 42 isn't that much
on bulk (ATM would be 1696) but at 50pps another 42 on IP makes
16.8kbit. So it's possible (but I don't know) that you are charged for
96.8kbit/s when using an 80kbit 50pps protocol.
Andy.
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