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Cable Modem Primetime Slowdown - Myth or Reality?
The Llama King asks: "SBC (SWBell, Pacbell, etc.) is whacking away at Time Warner cable in our area, running DSL ads that make fun of prime-time cable modem slowdown. And Time Warner-Houston/RoadRunner does seem to be having a problem in the past month with nasty ping times between 8 pm - midnight Central time (traces submitted to internal RoadRunner news groups show the problem appears to be a pair of routers at the gateway to one of several backbones). While this problem is recent, it begs the question - are prime-time cable slowdowns real or a myth? Can a well-configured cable modem network avoid the congestion SBC pokes fun at in their commercials, or is it inevitable? What are Slashdot users seeing?"
My ISP is Telenet/Pandora in Belgium. In primetime, net use seems to be slower compared to less busy times, but the bottle neck doesn't seem to be on the ISP's cable network. Downloads from the ISP's mirrors are always fast, even in primetime.
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FWIW, I have not noticed slow "times" of the day in my area. However, Planetcable was forced to stop accepting subscribers until Comcast had upgraded their infrastructure to support the additional traffic, so this could be an atypical situation.
In general though, I have noticed a substantial variation in the quality of service from day to day, and month to month. Some days or weeks at a time it's fine, and other times it's horrible (high ping/high packet loss) for months.
If liberty means anything at all, it means the right to tell people what they do not want to hear. -- George Orwell
Ameritech is running the same types of ads here in Ohio as well. What the ads don't say clearly is that you need to live next door to the central office if you want the maximum DSL bandwidth. For me, where I live nearly 3 miles from the CO, the best they claim for me is 128Mbps either direction. All that for $50 a month.
By contrast, the cable can handle huge amounts of bandwidth down and I'm pretty much assured a minimum of 128Kbps up. But, the cable bandwidth is shared among all my neighbors. It's important to realize, though, that all my neighbors aren't sharing 1.5Mbps down and 128Kbps up. It's more like 10.5Mbps down and 512Kpbs up. Business customers can get a dedicated line that gives them the entire bandwidth. Heck, Road Runner Columbus even offers what they call a "direct connection" to the internet at up to 45Mbps symetric.
Back to this topic, have I ever experienced a slow-down during peak hours? Nope. But I now live in a subdivision that I am certain isn't abusing the cable network. When I lived near Ohio State, however, I did find at times I was limited in bandwidth and Time Warner had troubles with their DHCP server getting overloaded. The worst data rate I ever was able to receive was somewhere near 500Kbps. That's many times better than most DSL lines. And at $45 a month (new price "adjustment"), it's easily the better choice.
Long, cute, or funny Sigs are just another form of over compensation, used by geeks, nerdz, etc.
Charter Cable here in Auburn Worcester Area has "ever changing pings". For sometime now I have never been able to get anything even resembling a consistent ping time or download rate. Somedays the connection flys the next its barely faster than a 56K modem. During the whole "Code Red" thing it was just sad, the light on my linksys router, for activity was just solid didn't blink at all. I called them several times and asked them to look into the reasons why their network was in such a state. I telecomute into my compant from time to time so this period was esspecially annoying. I am still monitoring several Code Red, Nimda, and related virus'es a day knowcking on the door. I guess in the end the moral of this story, the network only as good as those who run it, and even less good if they never listen to the users of the network who try to tell them whats wrong.
Power Corrupts,Absolute Power Corrupts Absolutely, leaving one person(group)in charge is absolutely corrupt.
I'm on a pretty idle cable node on a fiber loop with 512/512 service. Unfortunately, the connection appears very bursty, and actually never seems to get the rated speed. It appears that it transfers in a very quick burst for about 1/10th of a second, and then just sleeps/idles for about a second, then another burst. Problem is - overall, those delays really add up.
Well, mine stays the same most of the time and lately it's been better. Yes, during the evenings it's slower, but not that slow. My slowdown is usually caused by the DNS being a bit on the slow side. Once the address is resolved, it pops up fairly quick. That's most of it. A few times I can definitely say it was excess traffic in our neighborhood. New Years Eve was one where the network slowed to a crawl if it worked at all and this weekend, after the attacks happened, it seemed to be VERY slow and not fast until sometime Monday Morning. I get INCESSANT hits on the firewall since Code Red and Nimda. For a while, my activity light was lit solid for DAYS on end. I used to get 100-200 hits on the firewall per hour. Now, I still get too many hits and they are all coming from local IP's, but only about 10-20 an hour. I get VERY few hits on the firewall from IP's outside of road runner. It's all local traffic. Some of it seems to be pings from the provider as well. I think most of the hits seem to be Road Runner scanning the network looking for unpatched IIS boxes or unauthorized servers (it is in the agreement(no servers)folks and they have every right to do it no matter how stupid we think it is....).
I agree with the other person about the DSL ads and the fact that you have to be practically ontop of the CO to get the high speeds. I am only 1 mile away and I couldn't even get 128 K a while ago. Now I can get it, but it's all slower then and more expensive then my cable modem. Lately, Road Runner has been REAL attentavie to outages even. I remember one time I was out for a whole day and I didn't even call techsup and I had a credit on my bill the next month. That's cool. They KNOW when these outages happen. You should not have to call and bitch to get a credit. I do know that they are starting to be more attentive to customers, although their network issue page is usually out of date. At least they are updating the equipment gradually. I used to have a legacy modem, but after one REAL long outage, they gave me a new DOCSIS modem. Plus I think that some cable providers are loosening the IP restricitons and not hassling people who want to share their connection with other machines. Cable Modems are getting better. They have to or they are going to really loose it when the local phone companies get a clue about DSL and reduce price and make it competitive and make it so you don't have to live over the CO to get a high speed connection.
Gorkman
I've got Adelphia Powerlink here in South Florida. I run an infinite ping and a looped traceroute process from my home machine to my counter-strike server at the office. The mid-day 80ms xport times jump to a whopping 400-1200ms at 6:30pm on the nose every weeknight and stay there until well after midnight.
With a cable modem, the only difference is that the very first hop might also be oversubscribed.
A cable has a lot of bandwidth. That bandwidth is divided up into channels (on an NTSC analog system, channels are all 6Mhz wide, your channels may vary). Each internet cable box is assigned a channel (or set of channels, if channels only come in one size). Your next door neighbor's cable box might use a different channel, and thus not be in the same neighborhood.
Logically, a cable system is a tree, or set of trees, with the root of each tree at the cable company office, and the customers are the leaves. The thicker branches may run on fiber, they support more channels, and therefore more neighborhoods.
A wee tiny cable company may have a single T1 (1.5Mbps) line connecting to the greater internet, a large company might have several OC48 (2.5Gbps). The same is true for DSL providers.
ISP's either charge premium rates or they oversubscribe the service, or both. I don't see a primetime slowdown on my $180/month, 384K DSL line.
I have RoadRunner in Raleigh, NC and never see slowdowns. I always get the full 2Mb/sec when downloading with DAP. It's been this way for a long time since I first got it. They seem to do a very good job of subnetting people up.
But, all bandwidth can be oversold, not just cable. My friend had DSL in Texas and the telco oversold the local bandwidth and his pings went to 500ms just to his first hop at the ISP. At some point ALL bandwidth is shared, it just happens that DSL users have a piece of wire to the CO...but at the CO it all comes together, just like a loop on a cable modem.\
Marketing hype....
i wouldn't use just any dns server...
#1, even if it works now, they may update their configuration to exclude people who are not users of their network from running queries on the internet at large with their servers. Its not that hard to configure it that way, and its an easy way to reduce network usage.
#2, if there is any problem with that server, it may be difficult to resolve
an easier/more reliable step to take is make your own caching server that will go ahead and hit the root-servers for pointers if your isp's aren't working
Need a Catering Connection
Go into your preferences and enable the "Ask Slashdot" box. A lot of interesting "Ask Slashdot" stories never make it to the main page.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
I work from home as much as possible to enjoy a stable, fast Internet connection. At the office, we experience service outages every day (when you're ssh'ed into a remote server, you notice EVERY interruption, dammit) and frequent unexplainable slowdowns (can't blame Napster!).
DSL doesn't share between the CO and the home/office, but it does share SOMEWHERE. Today, for example, I downloaded StarOffice for Windows and Linux from Sun. The first Windows download was corrupted (?) and I had to download it again. Then, stupid me, I realized I downloaded 5.2, so I wen back and downloaded 6.0beta of Windows and Linux. These are ~100 each. So, in less than two hours, while working in the foreground, I downloaded over 400MB from Sun. My sustained transfer rate was over 180Kbps. I would never, ever, attempt such a thing during working hours at the office (on the DSL line). Ever. Downloading Windows patches is painfull enough, believe me.
Ping times are incredible on my cable modem. When I had home DSL I was happy to be able to ping 'nearby' IP addresses in 75ms. Same sites for cable are 10ms usually.
At home I run a linux server and have set up an emergency backup of our production and demo sites incase our dedi-hosted sites go down. I would never have thought of trying that with the office PacBell DSL.
I was a subscriber of Metricom's Ricochet until it died. I used my Ricochet modem at the office, rather than subject myself to the horrors of PacBell DSL.
It could be that my older neighboors don't stress the cable system as a younger demographic would. That could explain why I have NEVER detected a "slow time". And I'm on my connection constantly (ask my poor wife!).
Given the choice, I'll choose cable everytime.
-- @rjamestaylor on Ello
I don't know much about how to diagnose the problem, but my net connection at work is fine, and I don't notice anything funny when I list connections with netstat or watch total traffic with /proc/net/dev. So I assume it's just overloading of my provider's network.
My situation may be anomalous because I care more about outbound traffic, which is more limited with cable. I've never noticed any problem at home--but then again, I don't usually use my computer at home in the evening, and when I do it's web browsing rather than interactive remote logins.
My service is AT&T Broadband (formerly MediaOne) in 02140.
The evaluation of an action as 'practical' . . . depends on what it is that one wishes to practice.