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3Com's "Gamer" Modem Pings Faster?
An anonymous reader pointed us to 3Coms Gamer Modem:
they claim faster ping times and better online play. I'm more than a little skeptical here, does anyone have more info?
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The problem is that it doesn't always work. For some reason when my school recently upgraded half of their modems, I stopped getting connect speed messages from the modem (CONNECT instead of CONNECT ) about half of the time (go figure). I don't know what causes this, but I suspect there is some sort of communication that used to go on between the modems that doesn't anymore.
And no my modem isn't broken, my roommate has the exact same problem with his modem.
I read the internet for the articles.
I know that my modem (A Diamond SupraExpress 56i Voice) works in Linux with no hassle. Put it in, echo ata > /dev/ttyS0, it works.
couldn't be simpler...
If you ask me, those 'winmodems' are just sound cards with phone jacks. I would want a hardware modem even if I was using only windows...
These days a modem decodes the incoming analog signal (carrier tone(s) modulated into jumps within a 2D constellation in an IQ phase space) with complex DSP algorithms that funnel ultimately into a decision algorithm that spits out ones and zeros.
Maybe 3COM has come up with a new way of implementing the DSP RX recovery algorithm that reduces latency (for example not using as many delayed sampling taps, sampling the incoming signal at a higher rate etc). I doubt they could do much with the transmit side.
All in all, they might be able to reduce your modems contribution to ping latency by a small amount (ms's, 10's of ms?) but it is likely swamped by normal variability in the quality of service in the rest of the net.
Conclusion: maybe not a lie but still mostly marketing nonsense.
In a 1998 survey of various ISPs, it was noted that 57.9% of computers ping to stay online. Problem was, it was wasting too much processing time on the server, causing some ISPs to have special servers just to respond to pings. That was all dandy until some kids decided to play "ping-pong" with the servers in a synchronized attack, and brought the ISP to its knees.
Well, one Admin decided it was time to get back. He logged three days worth of pings from the most used accounts, and started responding to pings that didn't exist. The hack that the guys wrote to ping the computer in the first place was not ready for it, and took down the computer.
The Admin spread the news, and it caught like wildfire. Soon there were many variations of the program and each added it's own flavor.
Then it hit. One guy realized that the amount of time responding to valid pings was double what it should be. But if the ping response was sent at the same time as the ping, it would cut the time down to half.
Working on this theory, and collecting average ping reports. Mike Roe Chip, Network Administrator for ISP Communications, designed a protocol in which the ping responses are sent out at the same time as the ping itself. It's is correct 99.99999 percent of the time, according to his Pentium(TM) based calculations. To make up for any incorrect responses, it sends out a Ping Response Cancel Packet. The new protocol is called DCPP (Detect and Correct Ping Protocol), based on APT (Advanced Pinged Technology), and is coming soon to servers in your area.
Have you read my journal today?
Actually, it is much more sophisticated then simply detectecting dead frequencies, and moving the signal around, and in fact it was thought of sooner, and has been done for a long time.
Think of the signal coming in as a spectrum (like winamp shows you in it's default mode). This is basically a bar graph, with frequency along the bottom axis and power on the side axis. When somebody starts jamming on their bass guitar, you get bumps in the low frequency end. When they start playing the flute, you get bumps in the high frequency end.
As a side note, I believe mp3 encoding takes advantage of this concept to achieve it's high compression rates. It (metaphorically) saves the height of the bands, and reproduces those on playback. The higher the number of (more narrow) bands, and the more accurately you measure their height, the better your sound reproduction.
Any transmission medium will distort this spectrum to some degree. If you look at the spectrum on the sending end, and the spectrum on the receiving end, you will see it changed.
Your average phone line has a pretty narrow spectrum that it can transmit. I think it ranges from about 500hz at the low end, to 3500 hz at the top end. A normal CD reproduces sounds from 20 hz to 20000 hz. Unless you are a pre-pubescent female, you likely can't hear much above 15000 hz. ( hz=Hertz, cycles per second).
So anyway, if you want to get more bandwidth (lower lows and higher highs getting crammed through a phone line), there is a neat trick to doing it (which is also used by Bose on several lines of their speakers with great results).
1) Send a known signal through your transmission medium.
2) Receive that signal, and compare it to what you sent.
3) Before you send your next signal, pre-distort it, so that when your transmission medium reshapes it, it ends up at exactly the shape you wanted in the first place.
It's kind of like buying jeans that are not pre-shrunk... by them long, so that when they shrink after being washed they end up the size you wanted.
Simple, huh?
The reason this is becomming more and more common, and that data rates are so amazingly high for such lousy transmission mediums like phone lines, is that heavy duty signal processors are just now becomming affordable enough to embed in consumer devices. It's been around for quite a while, you just could not afford it.
Signal processors (DSP = Digital Signal Processors) are simple computers that have very limited functionality but do their job blindingly fast. This functionality is now to the point where it can be embedded in a single chip, and sold for a few bucks, but the engineering that goes into these things is staggering.
There are other methods of error correction that were necessary to get data rates up the 56k speeds we now see, but they are pretty complicated.
Bill Kilgallon
Mathematically impossible requirements are technically not against policy.
I'd imagine a heavy-duty pr0n session would be just as demanding; why just concentrate on gamers?
I suppose it's so they can market an Internet Gaming Modem rather than... well, my first few thoughts on what they could call it are pretty tasteless. I'll spare you all. This time.
3Com's website talks about how great this will be for gamers, but I think any Internet user would like more reliable uptime, faster connections, and faster pings. Why is this limited to gaming... it sounds to me like a scam to sucker all those high school gamers into buying a new modem, while real techies ignore it.
It'd be my assumption that these feats are achieved by being a hardware based modem rather than the all to standard software based modems. Anyone know if that is anywhere near true?
At what price learning? At what cost wisdom? The price is a man's peace of mind, and the cost is his life.
It was a joke! =)
The second part of my message actually details the way they could improve, not the speed of the connection, but the reliability of the communication between modem and ISP.
No matter what they do, though, 56K is the maximum that the FCC (and, AFAIK, the rules of physics) allows on a normal analog line.
So: faster speed is not possible, unless you switch to a digital (ISDN for instance) line. But better reliability may be possible -- again, we won't know unless 3Com gives away more info.
The right to offend is far more important than the right not to be offended. (Rowan Atkinson)
By disabling compression and error checking, it may decrease the latency of the modem.
Thus for reasonably phone line quality, ping packet and game synchronization packet may be delivered faster.
however, i doubt it if the phone line is very noisy, which increase packet drop (cause game stop for a moment or laggy)
So the 3com article says that an independent testing laboratory found that the game modem was 43% faster than other modems when connected to a 3com Total Control server. Here is the independent testing lab, and it's documents describing their test setup/testing methodology:
Henderson Labs
I have submitted a request to henderson labs to make the 3com test results publicly available. Please don't spam these people, I will post the results if/when I get them.
Can a modem be made better for gamers? You bet. Same way a protocol can be made better for gamers. It's all about LATENCY...
Why do we use UDP instead of TCP for gaming connections? Because we don't care about checksumming (checking for correct data) or compression (more data faster on average, but higher LATENCY), or RETRANSMISSION. That's the big one folks, retransmission. In a game, if you've lost a packet, you don't want it retransmitted anyway, because it probably is carrying the co-ordinates of a guy who's already killed you 10 seconds ago anyway. If you're tranferring a file, you definitely want that packet. (:
Real-time applications (read: games) need low-latency connections above all else, even an unreliable connection. Normal I/O needs reliable SAR (segmentation and reassembly). Those are very different goals.
Here's the REAL question: Does this modem do anything you can't reconfigure a normal modem to do using the hayes command set? Does it turn off some retransmission features that we can't normally turn off ourselves?
Or is it just a different set of default flags bundled with some lame games for l33t hax0rs in time for christmas?
3com, here is your chance to speak up. Engineering btw, not "product management".
-I am Jack's identity crisis, in full gear.
--
What happens when you outlaw guns
1) Compression in most modern modems is done using the V.42 specification. V.42 is actually very complex protocol which specifies frames that can be compressed. So you have to buffer data before compressing and sending. Error correction is done at the 'frame' level. There is a minimum latency to fill up the buffers before transmitting data.
Bottom line: If you disable V.42 you can subtract some milisseconds of your typical latency time. The connection is less reliable and have less bandwidth available, but its better for games.
2) The old fashioned UART interface is very slow. Even a 16550 uses a very small buffer for today's standards. This is one of the reasons to use a USB modem for better gaming experience. If this is a Winmodem, thay may have opted for a faster interface to transfer bytes from the CPU to the modem. Maybe they are using something like an ethernet interface, with larger packet buffers.
Bottom line: its possible to have a faster modem by using a faster interface instead of a plain UART.
Hi!
I'm an engineer in the 3Com modems group. The Game Modem is optimized for small packet sizes. Most games use tiny packets to indicate stuff like rudder position and etc, so this works better. Of course, short-packet pings fall into this category, too. Also, we ship it with some quite nice games in the box.
And, yes, it works just fine for the traditional things you use a modem for.
Happy Halloween!
Dog is my co-pilot.
Now, disabling modem compression is a well known tactic for decreasing ping time, and tools have been out to reconfigure Windows to do thus for years. That doesn't necessarily mean, however, that all these modems have different is a new driver disk.
Heck, new drivers shouldn't even be necessary. If I remember my AT command set, a simple AT&Q0 should kill both error correction and data compression.
You can't assume PCI == WinModem. What about those Actiontec call-waiting modem thingies? Those are PCI, and no, they are not WinModems.
Heck, new drivers shouldn't even be necessary. If I remember my AT command set, a simple AT&Q0 should kill both error correction and data compression.
If I remember right, there are even lower layers of error handling built into the analog signal handling.
Of course, now we're completely outside the range where I have a technical fucking clue, so we'll have to wait for someone with more knowledge of V.90 to step in.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
>Makes you wonder why the hell something like this wasn't invented years ago.
It was. Telebit was doing this 15 years ago, and I most sincerely doubt they were anywhere near the first.
Slashdot - News for Herds. Stuff that Splatters.
... and make sure that the One True Ping is still there.
Regardless of whether they can actually do some trick to reduce latency, it sounds an awful lot to me like another marketing scheme to differentiate their product and create demand.
Analog modem technology has run its course, and most people who would buy a modem already own one or would buy a no-name for less money. Creating a trick modem gives 3Com the chance to make their product different than the sea of other identical 56k modems.
Then there's the ISP effect. If they should prove popular enough, they may create enough pressure on ISPs to adopt this new "technology", enabling them to sell firmware options to ISPs with digital modem pools.
http://www.tidbits.com/netbits/nb-issues/netbits-0 15.html#lnk2
-- Support Ometz le-Serev.
Santa Clara, CA -
Sparked by the success of 3COM's new "gamer modem", modem manufacturers are racing to provide specialized modems to target audiences. Some recent offerings hitting the market this week:
AOLmodem - Internet giant AOL is offering a new modem this week that requires no phone line and boasts connection speeds of up to 1.7Mbps/sec. The modem is based on AOL's revolutionary "digitized FM noise" technology and will stream random bits into the users' computer at near LAN speeds. Andrew Taylor of AOL product management had this to say: "Like they'll be able to tell the difference. Ya right."
l33t-m0d3m: - Designed for the experienced script kiddie, this offering from L33t Designs Ltd. is a standard 56k V2 modem with the addition of quote "a whole bunch of blinking LED's that look cool". The modem also features a black metallic paint job and a leather hip holster, and comes bundled with "S.A.T.A.N".
J-pegger Plus: - Playboy's first venture into the consumer electronics market is this sleek velvet-covered modem. Optimized for what Playboy calls "maximum Internet suction", this modem includes software for automated binary attachment reassembly and hardware-optimized UUdecoding. A nozzle on the side of the modem acts as a plentiful "personal lubricant" dispenser, and the product comes bundled with a product Playboy calls the "Monitor Splashguard(tm)".
-mmm 0:flamebait.
(I'sa plead guilty, yo honor)
--
What happens when you outlaw guns
Some people have called bullshit on all of this, claiming that nothing can be done.
Smarter people have suggested that there is room to improve ping times by better buffer management and shorter latencies in the transmission pipeline.
One thing I don't think has been mentioned (but I may have missed it) is that one way to acheive better buffer management is to make the modem smart enough to look for an end of frame signature. If it detects one, it should imediately compress the data in its buffer and forward it over the line, rather than waiting for the buffer to fill if data is still coming in or a timer to expire if it is not.
Notice your use of the word "faster". What exactly does that mean? For a real world example, let's say you have a choice between an SR-71 (hypersonic spy plane), a 747 (jumbo jet), and the Exxon Valdez (supertanker) travelling from New York to London. Which vehicle would be "faster" to move:
Web surfing, file downloads, and online gaming all have different speed needs. Most people focus on bandwidth -- getting a 10Mb video in the least time, and who cares about a 2 second delay at the beginning. But for games, you want small blips of data sent without delay, every millisecond counts, and who cares if the overall data rate is lower.
Stuart Cheshire wrote an excellent lecture about this problem years ago. Click here .
A real shame it's taken so long for anyone in the modem business to pay attention. Also, it sounds like 3Com's solution is proprietary on both the user and server ends, meaning you can't just buy a new modem and run.
3COM cards in general are faster because of the way they handle things at the packet level. Instead of waiting for an entire packet to come across before accepting it, they look at only the first few bytes of the header and if they're good then pass it through. ie - if you have a bunch of 3COMs on a hub with a large collision domain then you're performace may suck because there are *lots* more short-rounds (short packets 64 bytes). a 3COM won't always catch these. Other than that, there aren't all that many settings to really change in software. So, 3COM may have started doing this in their modems now as well, not only their NICs.
Brent Deterding Data Network Planning and Support University of Missouri @ Columbia
It may be that this modem is "spoofing" some protocols, that is, looking at the data contents and doing something smart with it. This was originally done, I think, by Telebit 9600 baud modems, which did UUCP spoofing, and is also done by current fax modems, which may spoof certain handshaking. This typically requires pairs of modems that act as a black box, looking normal on the outside, and spoofing on the inside.
So is this just a buffer / latency issue where they reduce the total protocol layers between the modem and the (PCI) bus? It seems that you should be able to do some nifty optimizations that you wouldn't necessarily need for browsing/downloading (aside from streaming video), and these would help cut the time. Of course, real modems use less CPU than the winmodems, and that never hurts either, since things have to go much further into the system before they get returned... I always got better d/l speeds with my old USRs than any others at the time - but presently I'm on a cable modem 8^) which gives me an even better ping ;o)
"It's tough to be bilingual when you get hit in the head."
I know a few (well actually quite alot) of gamers that would buy one of these immediatly. I really don't think the question with the 3com people is: "is this modem better for games than others" but:"will we be able to sell all our stocked-up modems if we slap a "for gamers" sticker on them"
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Killroy Woz Here
In fact, Henderson Communications Laboratories, an independent testing lab, concluded that the 3Com Internet Gaming modem achieved up to 43 percent faster weighted average ping times than five other competitor modems tested this October when calling to 3Com Total Control® or Ascend Max server equipment.
As with all 3Com U.S. Robotics V.90 56K modems, the Internet Gaming modem includes x2(TM) technology to ensure backward compatibility with x2-capable modems and server equipment.
So it only works with their hardware on both ends, but is backward compatible. Naturally. Also:
The Internet Gaming modem also takes advantage of 3Com's exclusive line probing technology. This feature allows 3Com modems to dynamically create a signal pattern that optimizes throughput for that particular line, ultimately leading to higher levels of performance than other V.90 designs.
Line Probing? Heheheheh good one Beavis...
It probably just shifts frequencies and so on to test which signals are least likely to have interference due to line static. Then it uses those.
Which is a bit interesting.. Makes you wonder why the hell something like this wasn't invented years ago. I mean, if the modems can sort out speeds and so forth between them, why not freq. as well? Would saved me a hell of a lot of redials and restarted downloads...
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- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
Because your ISP uses a digital line (T1 or ISDN BRI) to serve your internet connection. They do not have banks of modems, unless it is a very old or very clueless ISP.
I'd rather see them concentrate on making affordable ADSL based modems. That is where the real speed and stability is at. Isn't G.Lite supposed to make it so we can use the same modem on any standard supplier and works by just plugging it into the wall as with a standard modem? *sighs* I miss my T1 when I go home. :)
At what price learning? At what cost wisdom? The price is a man's peace of mind, and the cost is his life.
..is the compression used to stuff more data down that dinky analog pipe! Anyone who played games over the modem in the 14.4 days will remember that turning off compression etc would speed things up.
This is due to the fact that for it to compress, it first has to get X amount of data or give up waiting and throw in a bunch of junk filler. Now, I'm sure the timeout is quite small - but it's not small enough to not affect gameplay.
This might be what it does, turns off the modem's compression. Might also disable MS's PPP compression stuff, as this would have some of the same effect..
There are some things they can do to increase their latency. Faster DSPs with shorter pipelines, streamline the drivers, ect. Unless they're comparing their new modem against someone's Winmodem with crappy drivers I'm not sure there will be a noticable difference. I don't know much about the technologies they use in modems.
As for digital vs. analog, digital signals don't propogate any faster down copper wire than analog signals. There are some advantages to going digital, but I don't think latency is among them. Unless you increase the bandwidth with the digital modem, then you can improve the latency (depending on how you measure latency).
With a traditional modem, there are three main sources of latency.
First, usually PPP is used for dialup IP connections. Unlike sync ppp over ISDN (or leased lines), it has to run asynchronous because it has no way of sending packets with the traditional command set. It can only send bytes. SyncPPP, on the other hand, sends whole packets delivered directly to the HDLC link layer. I know of no Hayes command extension that allows direct access to individual V.42 packets.
Second, with external modems, the data needs to get converted to serial and back to parallel. This adds less latency with higher port speeds, but even at 115200 bps, a byte still takes ~0.1ms to even get to the modem. This is less of a problem with newer internal modems, which just look like a 16550 to the software, but have no serial data path because what's looking like a 16550 is a clever interface for the modem chip itself.
Third, the modem needs to do error correction, which involves receiving a whole block (of 256 bytes usually) before it can be sent on to the computer. Anything without error correction could sometimes deliver low latency, but the first need for retransmission would ruin average latency, because the need for retransmission is not detected by the modem, but by the PPP layer above. (Imagine a 1500 byte packet that needs to be retransmitted because of a transmission error. Could take a whole second with older modems, at least 250ms with decent ones)
The real key to low latency modems would be implementing a direct packet access scheme for the PPP driver, or implementing PPP on the modem itself (ideally with some kind of link level compression). Then, with the other side properly tuned as well, a packet could be transferred with no more latency than is needed for the transmission itself, because PPP would eliminate the need for V.42 and CCP would eliminate the need for V.42bis. And - implemented either in hardware or in software with a broad data path to the actual line interface - these would be pretty fast.
There is some work on Linux-Softmodems underway. These should excel in latency, when finished and properly supported by pppd, because they implement most of the ideas above. They still need help, but there is source code already available here.
Holger
Hang on -- how can you get a faster ping if the pinged server is down, if there is some Internet congestion or if there is a backhoe (snip!) between you and the machine? =)
That does not make sense to me!
On the other hand, 3Com may have improved the connection reliability and line noise with clever hardware -- but if that's the case, I'd like to have more detailed technical info on how they did it...
Just my $0.02...
The right to offend is far more important than the right not to be offended. (Rowan Atkinson)
Consider for a moment that compression has a time delay factor intrinsic within it--the longer one waits, the more redundant data can be filtered out of a transmission block.
Modems, by default, execute Run Length Encoding(RLE) algorithms, which if I remember correctly are statements along the lines of "Here's a string of 64 0's" instead of literally sending the stream of 0's.
Of course, to *know* one is sending 64 0's, one has to operate on a 64 byte delay. So a key strategy for reducing lag is actually sending those 64 0's live rather than waiting the delay period.
This isn't really a bad idea--waiting for the delay period when highly tuned networking applications which would *never* send such a "low entropy"(translation: almost devoid of unique information content) string is foolish.
Now, disabling modem compression is a well known tactic for decreasing ping time, and tools have been out to reconfigure Windows to do thus for years. That doesn't necessarily mean, however, that all these modems have different is a new driver disk.
56K modem technology has been described as the biggest technical hack the industry has ever seen, and I'm inclined to agree. That it works at all is near-miraculous(although actually it doesn't really go as fast as advertised, thus 3Com's upcoming $5 coupon slap on the wrists for claiming net connections would be twice as fast).
Intrinisic in the protocol are error-checking codes. Error checking *also* introduces delays, as you need to wait for the data to come in before you can sum it. Reduce your error checking, or decrease the check interval, or tweak in any number of hacks, and lag can decrease.
Also intrinsic is connection recovery--by speeding this up, making this more effective, or both, 3Com gets an edge. That there appears to be specific functionality reserved for specific ISP hardware leads me to suspect there's off-standard code being put into use.
This isn't necessarily bad.
I'd be interested in more technical documentation as to what they've done--anyone from 3Com got a real link for the rest of us?
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
I recall Carmack making a .plan update or two while he he was talking about latency while creating the first version of Quakeworld. He stated a few changes which could be done in order to decrease latency.
:)
What your modem does, by default, is collect all data into a buffer, and then send it out all at once. The larger the buffer, the more efficiently compression can be performed upon it. All of the old Doom init strings that came with the game turned off your compression... and your error correction for that matter. (Wasn't it ATL0&M0&N0&B0 for a US Robotics?)
A common misconception is that some of the new midspeed connects such as ADSL or Cable give low pings because they have a lot of bandwidth. Rather, it's the lack of PPP. PPP adds about 140ms onto the ping time, because of the way it's designed: SLIP looks like it was written on the back of a paper napkin. PPP was.
Having strikingly low bandwidth causes for dropped packets, which is a very high possibility, especially since most (not all) packets in Quake games are UDP. However, other than this exception, bandwidth is secondary to latency when playing Quake.
That's why there isn't a notable latency difference between 28.8 and 56k. It's still PPP with error correction.
Probably the biggest killer in response time, even with a v90 connection, is going to be the compression. **NOT** the CPU time that it takes to compress and decompress a stream, but rather, the time for the stream to be transmitted. Remember that modems actually send data back and forth in groups of compressed data. One perhaps could make this faster by sending to the host the results of a stream before it is entirely decoded. But one could probably make it faster by turning compression off altogether. You'll have less *BANDWIDTH* that way, but a faster *RESPONSE TIME*.
That equipment is not so "weird"... It's actually a pretty common setup. 3Com Total Control and Ascend Max boxes are heavily used throughout the dialup world.
"You can never have too many elephants on your team."
Most modems have alot of extra processing to handle error correction, compression, and other things. I can imagine that a "Gamer's Modem" would cut out the non-essential steps such as V.42bis compression. It might also bypass some of the other bandwidth-enhancing tricks they do, trading bandwidth for latency.
Also, depending on how fancy they are, they might be doing some IP-level tricks, although I'd hope they're not. (This is reminiscent of the XModem-accelerating modems of several years ago that would fake an XModem ACK to speed up downloads, since XModem didn't stream.)
--Joe--
Program Intellivision!
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)