Point taken, but as a game player myself, I can see where Charismo is coming
from. The real ping time (as opposed to the displayed ping in the game) in
a game pretty much dictates the playability of the game. To an avid player,
this is just as important as a business's VPN or WAN connection. Gamers pay
for ADSL because they want as low a ping as possible. If there is ANYTHING
that can be done to get a lower ping, then they want it done. Thats the way
every dedicated gamer will feel, and there are a heck of a lot of gamers out
there using DSL. The ISP that comes out first with the option to disable
interleaving (even if only temporarily) will be attracting a LOT of new
customers (especially when flat rate becomes available).

Back to the original Question: Can interleaving be disabled to stop the
data being spread out over a higher number of packets? Do you need a
specific telepermitted router to disable it, or does it *have* to be done
from the ISP side? (and will Telecom allow it?) Anyone out there that knows
what to do with this one?

-----Original Message-----
From: Stephen Betts
To: adsl@unixathome.org
Sent: 11/24/00 11:49 AM
Subject: RE: ADSL and interleaving (Ping times)

I think that you will find ping times are largely irrelavant, most sites
block them and they have a low priority on the network / routers. I'm
sure that this has been mentioned here several times in the past
 
I cannot ping anything (game site or host ) from the LAN here, yet all
the games show ping times !!
This is because the games ping times are acutually calculated from
sending mostly UDP (or TCP) packets across the internet. Again typically
UDP is a not guaranteed for delivery and requires the application to
re-transmit the data. TCP is slightly better in that the Network Layer
will re-transmit the data and re-order the packets and if necessary
request re-transmission or missing packets.
 
Anyway, I get actual ping times to xtra, paradise and jetstream-games of
50 - 80 ms from my external adapter. I wouldn't complain about that.
International sites are typically nearer 200 ms so your gaming will
never be as good as local
 
The corporate networks I have supported are lucky to get less than
100-125 ms AKL - WGL, and the international links are 400-500ms they
also pay 2-5 times what ADSL costs for the privilage. (OK its not a fair
comparison but you get the picture)
 
I guess running a business is not as important as killing people as fast
as you can

-----Original Message-----
From: Charismo [mailto:charismo@xtra.co.nz]
Sent: Friday, 24 November 2000 02:44
To: adsl@unixathome.org
Subject: ADSL and interleaving

After a lot of research I discovered that what I wanted to do apparently
has to be done at the DSLAM which is a pity, here's an article which I
think many people may find interesting. If for example, I were to ask
telecom nicely, would they do as other ISP's have done around the world
and remove interleaving for just myself? Or at least reduce it to a much
lower level, as I understand it Telecom New Zealand set it to 30 ms but
I could be wrong. For a very prolific quake player I can tell you that
30 milliseconds makes all the difference. Ping is the *sole* reason why
we have ADSL, there are no other solutions for where we live that are
within our budget (Palmerston North) that come close, although I suppose
if I was in Wellington I could simply get cable which sports 30 ms like
pings... in any case I hope some lovely person from Telecom reads this
and considers my request. If we had to sign something to get it done
then we wouldnt' mind doing that ;). The URL is here:
http://www.dslreports.com/shownews/205
<http://www.dslreports.com/shownews/205> , sorry for posting the whole
thing here but I thought it would be more convenient.
 
In addition... this URL here leads me to believe that this can be done
on a per customer basis, in which case if the customer is happy with the
change, should it not be doable? http://www.dslreports.com/shownews/439
<http://www.dslreports.com/shownews/439>
 
Latency and Interleaving
For internet telephony or interactive applications such as remote
administration over a telnet session, latency is a key (and much
discussed) attribute of the connection.

At the moment, the class of users most obsessed with latency would have
to be the online gaming community. They are often buy entry level
residential ADSL lines, with high download speeds, and are dismayed to
read that friends on slower SDSL or IDSL lines are getting better ping
times!

The first reaction of a disappointed gamer is to blame the ISP for
routing inefficiencies or congestion, and although that is often the
root cause, there is more to latency than just many hops and/or long
distances.

ADSL modems commonly employ data Interleaving, which is a technique to
increase resistance to noise bursts on a line. Interleaving "smears" out
micro bits of data (interleaves them over time) so that a short burst of
signal destroying noise can only remove part of any given larger block.
Data blocks reserve some space for error-correction data.. which can
salvage a partially damaged block. Interleaving increases the chance
that noise on the line will only cause partial damage, not complete
loss. Thats the good news.

The down-side of Interleaving is that it increases latency! this is
because your little (say) quake movement packet is smeared out over
several packets before it can be fully sent or fully received.

ADSL modems with typical Interleaving defaults can be 10-30ms behind in
latency over equivalent speed SDSL modems... this means latency to any
point for some ADSL modems can be at best 50ms! On the same setup, the
aforementioned SDSL modems that typically add only 10ms. So for use of a
nearby server, ADSL Interleaving can be the biggest single source of
latency that you have.

Unfortunately, there is little clear information supplied with, or
available online, about what latency a given DSL modem or ISP connection
has built-in.

Some ADSL modems allow the user to turn off Interleaving, or turn it
down to a narrow range, at the expense of possible data-loss on noisy
lines. The Cisco 675, for example, has a full operating system inside
it, and one of the attributes of the ether interface is Interleaving.
See Randy Lutton's
<http://www.users.uswest.net/~rlutton/ADSL/Misc.html> US West page).
Some ISPs may be delivering this unit with Interleaving on, and some
off. In other cases, it is the DSLAM (central office equipment) that has
the Interleaving set, and this cannot be changed.

Regards,
Anton Smith
Silicon Dreams Hardware News and Reviews,
 <http://www.challenge-nz.com/silicon-dreams>
http://www.challenge-nz.com/silicon-dreams
 
 

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Received on Fri Nov 24 12:39:21 2000