Utilizing Comcast's Powerboost in conjunction with QOS...

Discussion in 'Tomato Firmware' started by bripab007, Apr 6, 2008.

  1. bripab007

    bripab007 Network Guru Member

    Long-time DD-WRT user, finally took the plunge to Tomato 1.17 just the other day and love it so far!

    The QOS is definitely better than DD-WRT's implementation, however, truth be told, DD-WRT v24 RC7 seemed to be quite stable and QOS worked well, for the little that I had defined (just FTP and Bitttorent class rules).

    Anywho, I've basically set up Tomato's QOS much like I had DD-WRT's configured, and this means I've defined my outgoing/uplink/upstream bandwidth to be ~90% of Comcast's advertised, non-Powerboost speed of 384kbs.

    Downside to this is, of course, I'm missing out on that, oh, extra ~1,000kbps of uplink bandwidth they give you for the first ~5-7MB of file transfer.

    Does anyone have any ideas on how Tomato could be configured to take advantage of this Powerboost / Speedboost?

    The only references I could really find to this problem are here: http://www.linksysinfo.org/forums/showthread.php?t=52905
    and here:

  2. szfong

    szfong Network Guru Member

    not possible with Tomato
  3. bripab007

    bripab007 Network Guru Member

    Well, that's just depressing :-(

    So, there's no way to program a script that would tell Tomato to use one set of QOS rules for the first ~5MB of throughput, then switch to another after that?

    So, do you have any experience with this and other firmwares?
  4. szfong

    szfong Network Guru Member

    It's just a set value, only way is to disable QoS on router and just dial down upload bandwidth on the applications you use. and allow Comcast to do their powerboosting stuff. All router firmware functions in manner because powerboost is erratic depending on time of day, level of network conjestion in the neighborhood.
  5. pharma

    pharma Network Guru Member

    You will still get the benefits of Powerboost without making any changes to QOS. Powerboost applies for any download throughput streams you have, and is variable throughout your sessions. With my comcast cable I have no problems downloading large ftp transfers (1 gig+) and bittorrenting at the same time -- I get the powerboost benefit even with the default Tomato QOS settings. There is a large thread at the Comcast HSI forum at DSLReports regarding Comcast's Powerboost feature and what to expect.

    I could be wrong, but I don't think you'll find this feature in Tomato as Jon indicated in the past limiting download QOS bandwidth streams is somewhat self-defeating in terms of maximizing overall download throughput.
  6. bripab007

    bripab007 Network Guru Member

    Yes, I understand that, and it's why I'm not trying to limit my downstream bandwidth whatsoever (I have not defined it in Tomato's QOS...well, I have merely defined an artificially high value in the Inbound Limit Max Bandwidth box). But I'm concerned that, by having to define my max outbound bandwidth as a percentage of my steady-state, non-Powerboosted number, I'm missing out on the Powerboost during outbound transfers.

    To be clear, yes, I'm seeing my Inbound speeds spike with Powerboost from my advertised 6mbps to ~15-20+mbps for short periods of time, but it's the outbound spike to ~1.5mbps instead of my advertised/steady-state 384kbs that I'm missing out on :frown:

    Perhaps I should also let you all know that the specific problem I'm trying to avoid is slow web browsing etc. from internal clients when an external client is downloading something from my FTP server (chomping down all my outbound bandwidth). I'm using a Linksys NSLU2 that has no way of limiting outbound bandwidth, that I'm aware of.
  7. pharma

    pharma Network Guru Member

    This happened to me under XP and also under Vista, but now slow web-browsing is a thing of the past when torrenting, streaming music, and web-browsing simultaneously. It is more related to the number of half-open connections allowed under these operating systems. When this happens your Windows Event log will display '4226', which indicates the tcpip max connection limit has been reached. The fix under both was to increase the number of half-open connections allowed by the operating system. Fortunately there is a fix for 32-bit XP and 32-bit Vista systems and can be found using google. Note the fixes are different for XP and Vista.

    There have been past threads in this forum on the topic ... if you do a forum search on you should find some excellent threads that present solutions to the issue.

  8. bripab007

    bripab007 Network Guru Member

    I actually already did that hack to increase the number of open connection in XP's TCP stack :biggrin:

    This issue, I believe, is specifically due to my FTP server allowing full bandwidth at any give time.

    To be sure, just using the default QOS settings in Tomato fixes that, let alone the minor tweaks and additions I put in there to add the outbound FTP classification, however, to use QOS, I must define a max outbound bandwidth. This is where I'm hampered by not being able to utilize Comcast's variable speed pipe. If I were to set my max outbound bandwidth to Comcast's peak Powerboost speed, I'd start dropping packets left and right once it got back down to the advertised, steady-state speed.
  9. szfong

    szfong Network Guru Member

    max outbound bandwidth limit is not a user configurable variable value that reset itself based on amount of "powerboost" your allocatted. inbound throttling, we all know is inefficient. outbound traffic is usually queued. trying to predict outbound "powerboost" is extremely difficult. For me at least, whats so hard in temporarily disabling your QoS when you need it and re-enabling QoS when you don't. It's best to base max outbound on actual rates and not the momentary bursts. Why not automate your uploads / remotely control your sessions if being in front of computer is inconvenient. outbound powerboost has little value in regular browsing, in my opinion.

    Also tcpip patching on vista is ill advised! The home basic edition is 2 half open, too little, but the ultimate edition are 25 per second, which is plenty. Just use linux or vista ultimate.
  10. bripab007

    bripab007 Network Guru Member

    Because I'd like to "set 'n forget" my QOS settings, silly :)

    I'd rather not have to wait until my internet connection slows down to find out that someone's downloading from my FTP at which point I would need to go turn off QOS. Which wouldn't really help anyway, because, again, my FTP is going to give them as much bandwidth as it can.

    Should I then call that person to tell them to cap their connection speed from me during the duration of their transfer? :biggrin:

    I'm just trying to tailor my network to operate the best it can with as little input as possible. Isn't that what any good IT person strives for? :biggrin:
  11. szfong

    szfong Network Guru Member

    just taylor the upload speed to about 90-95% of sustained speeds. and you'll be fine and shaping outbound traffic to your particular needs.
  12. bripab007

    bripab007 Network Guru Member

    I hate to sound repetitive, but I've already described in my previous posts that this is exactly what I've done (and had been doing for years on DD-WRT's QOS, as well), but I was looking for a way to take advantage of Comcast's variable outbound speed.
  13. pharma

    pharma Network Guru Member

    Actually 25 is still too little for Vista Ultimate - and you can tell by the '4226' Event log errors. The current Vista hack increases the amount to 250 per second which resolves any performance issues related to simultaneous torrenting, ftp, or web-browsing activities. The main reason MS set these limits is due to a possible increase in virus/malware on PC, but I have had no "new problems" in this regard compared to the pre-hack implementation.
  14. pharma

    pharma Network Guru Member

    You can not shape the bandwidth amount to apply PowerBoost configurations to specific outbound streams in Tomato . If that is something you did with DD-WRT and find added value from using it, you should definitely switch back.

    I'd give Tomato a week to really see if it makes any difference. My experience is it won't if you make the necessary changes to the OS to account for the half-open connections issue.

  15. szfong

    szfong Network Guru Member

    actually the # of half open conn should settle down in a few minutes. I set my torrent app to 80% of windows's max for net.max.halfopen. these are half-open connections, i don't mind taking a few min. longer to reach ~1500 simultaneously tracked connections. creating too many conn. too quickly can cause RED flags to go up on your isp's routers :-(
  16. bripab007

    bripab007 Network Guru Member

    I didn't say I had been able to take advantage of Powerboost via DD-WRT's QOS. I said that I've been using DD-WRT's QOS for a while, using my sustained speed as max outbound value, just as I'm now doing with Tomato. Tomato's QOS works at least as well as DD-WRT's, FWIW.

    Thanks for your help, guys.
  17. netprince

    netprince LI Guru Member

    I'm not sure how motivated you are at making your QOS work with powerboost, but it can be done in openwrt with some patches. If your familiar with the linux command line and dont mind skipping the web-interface, and even dont mind applying patches, here's a link:


    Specifically, you want to use the bursttime patch.
  18. bripab007

    bripab007 Network Guru Member

    Well, hell, now we're talkin' :)

    Thank-you, sir! I've kinda fallen in love with Tomato's web gui, and am not as accustomed to Linux CLI as I am, say DOS :)

    However, I may give it a whirl.
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