Router Latency When Using P2P

I'm interested in using a voice-over-IP service, but have noticed that the
latency on my router increases to about 600 ms when my connection is max-ing
out under p2p traffic. It shouldn't do: I've only got a 512 connection, but
the router is specified up to 8 Mbits/s. A 600 ms latency would make VoIP
call unbearable!

Is this a specific problem to my router, which has a Connexant chipset, or
is this common to all low-end routers?

Thanks,


Richard

"Harry Broomhall" <(E-Mail Removed)> wrote

> What on earth makes you think "It shouldn't do"? If you are maxing
> out a connection then any attempt at getting performance out of a line
> will not happen!

Perhaps I'm mistaken, but my understanding is that bandwidth and latency are
different things. Just because the pipe is full doesn't mean that data
should take longer to get into the pipe.

Yes, on the uplink, the router needs to make a decision about which packets
to drop, but why should that decision take a whopping 600 ms?

Perhaps I shouldn't have used the term "maxing". This effect occurs even
when the connection is far from full. It's such a problem with KaZaA that I
don't use that app any more.

If my router was only specified for 512/256 connections, then that might
imply that it was designed for less heavy users than myself and its
performance not being as good as other routers. But it isn't, so I'm still
confused...


Richard

Richard Sacks wrote:
> "Harry Broomhall" <(E-Mail Removed)> wrote
>
>> What on earth makes you think "It shouldn't do"? If you are
>> maxing out a connection then any attempt at getting performance out
>> of a line will not happen!
>
> Perhaps I'm mistaken, but my understanding is that bandwidth and
> latency are different things. Just because the pipe is full doesn't
> mean that data should take longer to get into the pipe.
>
> Yes, on the uplink, the router needs to make a decision about which
> packets to drop, but why should that decision take a whopping 600 ms?
>
> Perhaps I shouldn't have used the term "maxing". This effect occurs
> even when the connection is far from full. It's such a problem with
> KaZaA that I don't use that app any more.


This is a budget router you are talking about, what makes you think it can
prioritise traffic? One packet might look just the same as the other to it.
Spend more if you want something capable of deciding what to drop. Look for
one hat supports Layer 3 switching,
http://www.synetrix.co.uk/products/voice_data/index.cfm for an overview.
http://makeashorterlink.com/?K28A45C75 for more Google links.

S. Althaf

"Clueless" <(E-Mail Removed)> wrote

> This is a budget router you are talking about, what makes you think it can
> prioritise traffic?

I don't!
If I had traffic shaping, then I wouldn't need to post here
This router is so budget that I bet it just dumps every Xth packet. Still,
that requires numbers to be crunched.

> One packet might look just the same as the other to it.

Likely so, in this case. Only if the router had some intelligence, such as a
relatively simple weighted round robin scheme, would pay attention to packet
parameters.


Regardless, none of this answers my question! Is this a common problem? Is
600 ms typical?

Thanks, chaps.


Richard

On Mon, 4 Aug 2003 18:37:23 +0100 and in article <UKwXa.54120
$(E-Mail Removed)>, Richard Sacks said...
: Regardless, none of this answers my question! Is this a common problem? Is
: 600 ms typical?

I have a conexant based chipset router as well and do not experience
this. *however* I do not upload at all when using P2P applications and
am using Routed IP (ie, non NAT).

I think what you are finding is inherent a problem on TCP/IP - see here:

http://homepage.ntlworld.com/robin.d...ps/downup.html

--
CB

On Mon, 4 Aug 2003 17:19:52 +0100 and in article <bgm13r$fg4$1
@news8.svr.pol.co.uk>, Morgan said...
: > It shouldn't do
:
: Could you explain as I would have thought, regardless of the specification of
: the router that you have, as all of your bandwidth is being used for P2P
: wouldn't that account for the issue rather than a fault with the router as you
: suggest...?
:
It's a fault in TCP/IP:

http://homepage.ntlworld.com/robin.d...ps/downup.html
--
CB

I think you're missing the point Richard . Think of the router as a bridge
with cars going over it - latency being the transit time of a car over the
bridge, plus the roundabout before it..

All the cars enter the bridge via the roundabout. Once they clear the
roundabout, they pass across the bridge.

If there is a constant flow of traffic across the bridge, such that the
density of traffic is quite low, then the transit time is constantly low.

If however you pump so much traffic onto the roundabout (P2P traffic) that
new traffic joining simply cannot get onto the roundabout, transit times
increase. The time to cross the bridge is constant, but there is a delay at
the roundabout.

You simply cannot exceed the capacity of the bridge, and that¹s what you are
expecting.

As to the 600ms - it could be any number at all, or not at all if the
bridge is full. If I set up an FTP server and access it at full capacity, I
cannot browse the internet at the same time - requests go out but nothing
comes back. The lag is therefore much more than 600ms - virtually infinite
in fact.

Stop downloading porn long enough to make the call imho


On 4/8/03 5:04 pm, in article jnvXa.54095$(E-Mail Removed),
"Richard Sacks" <(E-Mail Removed)> wrote:

> I'm interested in using a voice-over-IP service, but have noticed that the
> latency on my router increases to about 600 ms when my connection is max-ing
> out under p2p traffic. It shouldn't do: I've only got a 512 connection, but
> the router is specified up to 8 Mbits/s. A 600 ms latency would make VoIP
> call unbearable!
>
> Is this a specific problem to my router, which has a Connexant chipset, or
> is this common to all low-end routers?
>
> Thanks,
>
>
> Richard
>
>

"CB" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ...
> I have a conexant based chipset router as well and do not experience
> this. *however* I do not upload at all when using P2P applications

Share some files you stingy bastard.

K

On Mon, 4 Aug 2003 18:55:19 +0100 and in article <1060018771.89778.0
@despina.uk.clara.net>, K said...
:
: "CB" <(E-Mail Removed)> wrote in message
: news:(E-Mail Removed) ...
: > I have a conexant based chipset router as well and do not experience
: > this. *however* I do not upload at all when using P2P applications
:
: Share some files you stingy bastard.

And have the RIAA and it's co-horts onto me? No thankyou very much.
Uploading on my connection is hit and miss anyway, my download rate
slows when I start to upload and the whole connection just goes sloooww.

--
CB

Richard Sacks wrote:
> "Harry Broomhall" <(E-Mail Removed)> wrote
>
>
>> What on earth makes you think "It shouldn't do"? If you are maxing
>>out a connection then any attempt at getting performance out of a line
>>will not happen!
>
>
> Perhaps I'm mistaken, but my understanding is that bandwidth and latency are
> different things. Just because the pipe is full doesn't mean that data
> should take longer to get into the pipe.
>
> Yes, on the uplink, the router needs to make a decision about which packets
> to drop, but why should that decision take a whopping 600 ms?

Because it has buffers - that is how it works. I am surprised it is only
600ms.

> Perhaps I shouldn't have used the term "maxing". This effect occurs even
> when the connection is far from full. It's such a problem with KaZaA that I
> don't use that app any more.

If you send more data than can go out then it is buffered. Buffers are
often many K in size and 600ms is not bad. This has nothing much to do
with the speed of the link at all.

> If my router was only specified for 512/256 connections, then that might
> imply that it was designed for less heavy users than myself and its
> performance not being as good as other routers. But it isn't, so I'm still
> confused...

Nothing to do with it. The only impact is that most routers have a fixed
size buffer and so a faster link is inherently lower max latency.

--
_ Rev. Adrian Kennard, Andrews & Arnold Ltd / AAISP
(_) _| _ . _ _ ADSL, fixed IP, monthly contract http://adsl.ms/
( )(_|( |(_|| ) SpliceCom VoIP based PABXs http://aa.gg/
~~~~~~~~~~~~~~~~ Bond two ADSL lines? http://www.FireBrick.info/