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CPU muscle vs. new wireless protocols?

Discussion in 'Tomato Firmware' started by jsmiddleton4, Nov 21, 2013.

  1. jsmiddleton4

    jsmiddleton4 Network Guru Member

    Good morning,

    Yes I know, this is a barely about Tomato firmware question. I simply don't know where else to find a group of folks with the expertise represented on this forum to ask.

    I'm having network bog down issues. I have an Asus RT-N66U currently using the latest .2 variant from Toastman.

    We have, as others have as well, seen an significant increase in wireless devices, iPads, iPhones, Laptops, stereo equipment, bluray players, etc. In terms of regular wired LAN traffic same thing, NAS storage with media files being watched via LAN attached media playback devices, streaming internet radio stations, etc.

    In other words the CPU even in the N66U is getting pushed past its ability to deliver.

    In my researching almost everything is focused on wireless protocols. Which is great and glad to see the information BUT without the cpu muscle to back it up faster wireless connectivity washes out after a few clients connect let alone a handful of demanding lan clients.

    I have searched the Tomato forum for "Will Tomato support ______________" be it Netgear R7000, Asus 68, etc. And at that point my post is remotely connected to Tomato.

    I do want to try and stay with a router that is supported by the folks who are behind Toastman, Tomato, Shibby, etc. The Tomato firmware is of great value as is RMerlin's ASUS tweaks.

    And yes this is all about educated opinions so in terms of opinions just know going in no one is right or wrong here.

    But where does this whole CPU thing fall and what product addresses what I dare say many of us are seeing with home networks getting bogged down?

    Is there a better network topology to implement such as using a switch that while connected to the router/internet clients that mostly stay within the LAN are routed through it? So NAS devices, media servers, etc., all run through a multi-port switch to talk to each other and not through the router for the most part?

    Or does it even work that way? Does using a multi-port switch with LAN devices connected to it but it connected to the router not mean the router isn't involved when those devices talk to each other?

    Is the best solution a new router with one of the new duo-core cpu's? Netgear at the moment is only one with 1ghz but you know that is going to change quickly.

  2. jerrm

    jerrm Network Guru Member

    The CPU comes into play with routing and bridging(wired to wireless). Wired-to-wired on the same subnet traffic should never seen by Linux or the CPU unless you have done something unusual with the setup, so adding a separate switch won't have any impact.

    Using a separate access point can be a little help if you have a lot of wired to wireless LAN traffic - saving the router CPU strictly for routing.

    The new ARM CPUs will help with the high bandwidth internet connections, or a 10+ year old PC will run rings around any of the MIPs routers.
  3. jsmiddleton4

    jsmiddleton4 Network Guru Member

    Same can be said for home media servers. But what is practical and easy to setup and use make setting up an unused PC to be a router/switch is a matter for debate.

    What I'm seeing now is when several wireless clients connected to the Asus N66U I have stuttering in the media file playback/flow. The media files are connected wired but the NAS's are connected to the router's ports.

    Hence my question about a switch and if getting the traffic off the router's ports would make any difference.

    Wireless clients stop, media playback perfect.

    Seems to me that is horsepower in the router BUT I am speculating.
  4. Victek

    Victek Network Guru Member

    ... new CPU's can overcome with brute force but problem is well known by 99% of forum followers because this subject has been posted hundred? times. Broadcom black box drivers (ethernet and wireless). Open the code and then CPU will work without waiting and halting exceptions and unknown messages from network drivers, sirq will be minimal and problem solved.
  5. jsmiddleton4

    jsmiddleton4 Network Guru Member

    "subject has been posted hundred? times"

    Really? Because search doesn't show any threads about the new CPU's and the impact on usability. Only ones I see are the "Will Tomato support this or that router..." threads. Which is not what I'm asking.

    Sorry if I missed the threads about this subject. Can you point me to them Victek?
  6. Victek

    Victek Network Guru Member

  7. Toastman

    Toastman Super Moderator Staff Member Member

    Not 100% sure if this is what you are looking for. But I see you have a lot of devices, too many for the usual router's 4 ports. And you are asking about an additional switch, so here goes.

    Yes, you can keep all local traffic away from the router by plugging all of your devices into a gigabit multi-port switch, (e.g. 16 port, these are now relatively inexpensive. I use many TP-Link unmanaged 16 port switches over here).

    Then take a single LAN cable from the switch to the router, to handle any traffic that needs access to the internet. That way you keep all local traffic handled by the switch, and the router sees only internet traffic.

    To handle wireless clients you have 2 choices.

    1) Use the wireless in the gateway router. I don't like this as it is a source of slowdown and potential instability.

    2) Add a wired access point - you have a choice of add it to one of the router's LAN ports or to the switch. I always use the switch.

    However, if you have several wireless clients competing for bandwidth on a single access point, this may starve individual clients of bandwidth and cause stuttering.

    Hope this helps.
  8. jsmiddleton4

    jsmiddleton4 Network Guru Member

    I'll certainly take a look at those Victek but I'm not asking about download speeds.

    I'm asking about CPU impact on download speeds and throughput.
  9. jsmiddleton4

    jsmiddleton4 Network Guru Member

    "Yes, you can keep all local traffic away from the router by plugging all of your devices into a gigabit multi-port.."

    Thanks. Will look at doing so. Experimenting now with Avatar playing back via media server and using some older non 1gb switches. Kids not hammering wireless at the moment.
  10. Victek

    Victek Network Guru Member

    Read the text, not the title...
    CPU impact .. if you read it it's a close relation with CPU-Netfilter-Driver .. the most powerful CPU can't do nothing when it's not understanding or responding to instructions not observed in the code. Use a 8 cores CPU in latest laptop without operating system installed, switch ON and wait .. what's doing? nothing .. so this is the situation when one driver send an unobserved instruction to the CPU... do nothing until watchdog says, don't be lazy, go to next row ..go..go!. It' a crude example but it's what tomato does with wireless or ethernet section, Do you understood what's going on now?...
  11. jerrm

    jerrm Network Guru Member

    As I said, wired to wireless traffic crosses the linux bridge and does impact CPU usage. A separate access point may help. If you have a separate access point, then all the wireless traffic just looks like wired traffic to the router.

    Whether that access point is plugged into the router or an external switch won't have any impact on CPU. All the wired LAN to LAN traffic in the same subnet should be handled entirely within the switch chip and not touch Linux or the CPU (unless you have done something unusual).

    It wouldn't surprise me if some external switches handle gigabit level switching more efficiently than the router's switch chip, but that is not a CPU speed issue.
  12. jsmiddleton4

    jsmiddleton4 Network Guru Member

    "wired to wireless traffic crosses the linux bridge and does impact CPU usage."


    I have an E3000 with Toastman's firmware as a wireless AP. That's been in place for some time. Added a TPLink 8 port 1gb switch yesterday, on sale locally for $20 US, and noticed some improvement last night. Have all NAS's, media devices, etc., all running through a switch of some kind and off the Asus RTN-66U.

    The stuttering for NAS fed video stopped. That is progress.

    Other devices connecting to the internet still getting bogged down when one wireless client in particular does any heavy downloading like TV Shows.

    I have not configured QOS and might give that a shot. However I am not 100% certain we had this symptom when using RMerlin's Asus variant. I simply don't recall. Not saying it is Toastman's. Just saying I didn't do an A to B test regarding this particular issue so have nothing to go compare or conclude.

    I also don't want to keep throttle clients back just to make a system sorta work when the real solution is a new more appropriately applied router to handle the increased traffic/volume/usage.

    Netgear R7000 keeps calling my name......
  13. tarmdjur

    tarmdjur Reformed Router Member

    I'm pretty sure R7000 won't help you if RT-N66U is too weak for your purposes. Get several "boxes" for different tasks, or a cheap dual-nic PC with pfSense for routing and use your RT-N66U as ap only. If the wireless gets bogged down, use several ap's with different SSID's set on different channels in 5GHz.

    You can easily build a pfSense PC for the price of a R7000 and never be bothered with the cpu bottlenecking again, right?
  14. jsmiddleton4

    jsmiddleton4 Network Guru Member

    I can get a R7000 for just over $190 USD.

    First thing I'm going to do however is reflash with RMerlin's firmware and do some testing.

    Could also drop in another AP fairly easily.

    Actually the first thing I'm going to do is learn about and setup QOS with Toastman's firmware.

    THEN if no improvement look at reinstalling RMerlin's.....
    Last edited: Nov 22, 2013
  15. jsmiddleton4

    jsmiddleton4 Network Guru Member

    I went back to RMerlin's to experiment and even without QOS enabled I have no stalling for media playback when still downloading other TV episodes. The same context that caused issues when using Toastmans.

    Not sure why, just reporting observation.
  16. Victek

    Victek Network Guru Member

    So, you said that using RMerlin firmware in RT-N66U everything it's OK and using Toastman build you have problems, right? Did you tried other dev's tomato builds? Take in mind that code for tomato is slightly different on each dev version now, not only by the features...

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