DMT vs CAP Encoding / DSL Upgrade Downside?

cmark asks: "I recently 'upgraded' my Qwest DSL from 640/272 to 640/640 to increase the bandwidth of my Counter-Strike server. When I got this upgrade, Qwest sent me new a new router (a Cisco 678 to replace my Cisco 675) and changed the encoding from CAP to DMT. In this process I do not have greater bandwidth and thus less lag on the server but I have increased latentcy (higher pings). My ISP says that it is the encoding, something about the interlacing that they cannot explain. Qwest says that it is not the encoding but must be some routing that my ISP is doing. What is causing the increased latentcy and what can I do about it?"

"A traceroute looks normal to me... If I was hosting a website or using it for some other business purposes I probably would not care but in gaming a low ping is crucial, I have lost the regular players that I had and the server sits empty most times all the while costing me more money! Qwest also says that I cannot go back to CAP even if I downgraded, since they are migrating off of CAP."

interleave

[meanmachine]

DMT makes use of interleave to minimize the change of errors (they can recreate the original data as onlyy a portion gets corrupt in case of a disturbance)

This mechanism de creases the error bitrate from 1 in 10^3 down to 1 10^6
However, it increaese delays due to the interleaving.

ALSO the TCP/IP will take care of the retransmissions in case of a problem. Ping times can be as high as 160mS one way and as low as 20mS with interleaving turned of.

Re:interleave

[complex]

i concur with this information. (note: i used to work for verizon dsl)

meanmachine is right, the bit error rate isn't critical for you. the latency is.

the solution, for you, luckily, is nearby. the cisco line of dsl routers has changable interleaving settings! all the info i can find now is at dslreports [dslreports.com].

if this doesn't work, then the solution is to get your provider to turn off interleaving. this will be difficult. repeat: this will be difficult. you'll probably have to beg, beg some more, beg to 20 different people, and then they still won't do it. ask to talk to a dsl tech, supervisor, whatvever. but if your cisco can't do it, then getting them to change it at the far end is the only way.

good luck.

i'll try to post more if i can find it.

complex

Re:interleave

[complex]

hope this isn't considered karma whoring, but the cisco 678 documentation will be useful in the course attempting the interleaving change. fully searchable, unlike your dead tree version! (if you even have one, dsl providers typically get the modems sans box, packaging and docs)

complex

That is: 160mS with interleave 20mS without it

[meanmachine]

oops see subject. 160mS is with interleave on max.

DMT has advantages, disadvantages

[isdnip]

CAP is basically obsolete. It was the first ADSL technology, and has worked okay in some cases. But it has one big disadvantage. CAP causes crosstalk. It puts a lot of energy into some narrow spectra, and it leaks into adjacent wire pairs. The FCC is cracking down on this and CAP might not pass future standards. If a telco deploys one DSL line out of a hundred subscribers, CAP will work, but as the subscsriber density rises, CAP causes trouble

DMT spreads the signal differently, and thus has less crosstalk. It is thus the "standard". It doesn't always perform as well and is more latent though.

ADSL or SDSL

[lordkiwi]

Did they specificly say you where using ADSL or SDSL. ADSL Is slowed by two way trafic.

read http://www.dslreports.com to stay up to date

Re:ADSL or SDSL

[cmark]

adsl is what I have.

More info and thanks

[cmark]

I have asked Cisco if there is a way to turn off the interleaving from my side and they have informed me that it must be done on the provider side (great service from cisco btw!). I will contact qwest tomorrow when the business office is open and post their response to my request to turn interleaving off or down since their techs tell me that the line quality is great.
I am not hopeful though, everything else I have asked of them has been no or yes but then they screw it up so why should this be any different.

Qwest sucks!

[cmark]

I made my request and sent them as much supporting info as I could find.
The tech did not know what I was talking about but, said they would look into it.
Then came the responses.
First they said they did not understand the request but that there is not problem with my line (duh!)
Then after I re-explained it, they told me that all such requests must come from my ISP (vector internet services inc. in this case. Qwest supplies the line, VISI the IP etc.) So I called VISI who has already told me that they have been though this before and that Qwest will not budge. They reiterated that Qwest is not going to do it and would not even reattempt the request because they had been through it so many times. I then called qwest back and asked why they sent me on a goose chase in the first place knowing that they do not fullfill such requests.
The customer service rep said that she would take it to the third tier support (developers as we all know), they denied all knowledge that it was even possible.
When I countered that Cisco (who made the DSLAM) had informed me that it was possible and offered to bring them in on a three way call, the rep refused and said that they must not have bought in on that 'option' from Cisco.

I guess I wil give up and find some other way to get my CS server on the internet. poo poo on qwest they should allow this kind of flexibility to their customers! Must be that old monopoly mentality.