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B/G Protection on RT-AC66U

Discussion in 'Routers' started by tbosa, Aug 26, 2012.

  1. tbosa

    tbosa New Around Here

    Aug 14, 2012
    Hello. I've searched and cannot find a direct answer to what the little check box for "b/g protection" next to the "wireless mode" drop down box in all ASUS routers' firmware does for a person. Does it mean it "protects" wireless b by making sure the router stays compatible for B devices? Or, does it mean it adds some kind of extra security to the B and G wireless transmissions? I don't have any B devices in my house and unless this setting does something else for me, I'd rather disable it.

    Thanks in advance!
  2. tipstir

    tipstir Very Senior Member

    Aug 16, 2008
    South Florida
    Protection mode refers to a mechanism for the G radio. Since a legacy B radio device would not decode radio signals at G rates, a protection mechanism was developed for the new G radio and the B radio to co-exist on the same network. When protection mode is enabled, every packet sent on the G rate would require initiation of the sender.
    dushko likes this.
  3. thiggins

    thiggins Mr. Easy Staff Member

    May 18, 2008
    Enabling "B/G" protection ensures that the AP waits long enough for these slower protocols.
  4. professordave

    professordave Occasional Visitor

    Jan 22, 2013
    Suppose there are no b clients, but there are several g clients.

    I currently run without this checkbox.

    I have an ac66u, no ac clients yet, just some n and some g clients.
  5. RadoFan

    RadoFan New Around Here

    Jul 8, 2015
    Can I disable b altogether on an RT-AC66U?
  6. sfx2000

    sfx2000 Part of the Furniture

    Aug 11, 2011
    San Diego, CA
    Recommendation is not to disable 802.11b - not that one wants 11b clients to attach to your AP, but just in case there are other 11b networks (such as Printers using AdHoc) - if they cannot understand your AP's beacons, they have a good chance of stepping on your network...

    I generally run my 2.4GHz in mixed B/G/N mode, WPA2-AES - most 11b clients can't do WPA2, so this is a good way of keeping them off your WiFi...

    Ideally, one doesn't want any 11b around, as it can take an 11n network down into non-ERP* protection, and this can have a significant impact on the 2.4GHz band.

    ERP mode is also known as 11g
    HT is 11n
    VHT - while not official in 2.4GHz, this is basically how TurboQAM is presented...

    (This is also why I always recommend mixed B/G/N with Turbo disabled - N-Only will go into Protection if an 11g/11b is seen during the mandatory OBSS scans, and Turbo/VHT can have interop issues with older 11n/11g clients, and I've seen 11b clients crash outright with AP's broadcasting VHT support in 2.4GHz)
    buddyp and Ah-Pin-Kor like this.
  7. dushko

    dushko New Around Here

    Feb 12, 2017
    I DO KNOW this is an old thread, but no real sensible explanation inside, and this topic may still be relevant for the next couple of years.

    We tend to overcomplicate stuff in pursuing that last bit of Mbps/dB or whatever else.

    tipstir (post #2) was right and I would add that b is DSSS mode and g(+onwards) is OFDM.

    thiggins (#3) - just to clear that up, that does not mean, it would slow down, it just wouldn't discard the packets as "noise or whatever.

    RadoFan (#5) yep, to disable 802.11b, select Wireless Mode : N only (it's under Wireless/General)

    sfx2000 :
    that's just wrong! These "recommendations" come from "professionals" who read a paper back in 2000(no pun intended) and did not bother to re-read. These people are of course real professionals, but of the kind who buys this technology, not the kind who designs it, therefore it's not even harsh to say that all they say is just a guess, as good as anybody's.
    That what you refer to might have been the case with some draft 11g or some other pioneering 11g equipment, but I think it could have been remnants of a bad draft implementation - to slow down for backwards compatibility or whatever. Even if it was the other way around this stuff was solved many years ago.
    All these conflicts are in software and unlike hardware, where a new piece might be more delicate, software tends to get more robust. If 11b knows AdHoc, then rest assured it will not be a problem for the newer equipment. It's the other way around: In the old days, when two 11b APs shared the same airspace, they had to be reduced to half power - this, in my book, implies that the new equipment might step on 11b's toes. Maybe it could take down a really poor 11g, but it's not taking down 11n - that will just not happen.
    To support this, I have a "too new" 11b device (everyone was surprised a flagship phone had no 11g at that time) - Sony Ericsson P1i (it knows WPA2 and has a fairly nice range btw.) - and while my other devices show varying Tx/Rx in the ClientsList, this one shows a steady 1/11 (Mbps) - so this is clearly shows that the 11b is the "dumber" device, therefore that is the one you want to protect. Just like you wrote yourself in your last paragraph: the 11b would crash - that's it, and yes, maybe the certifying authority decided (did not and will not look this up) it would be great for an 11n device to ASSUME that a noisy 2.4 Ghz spectrum means all the "archaic" 11g devices need to be ignored and as we know assumption is the mother of f-ups.

    You know, when people talk about child labour in the factories, I look at the UI of these devices, and know that there certainly is child labour somewhere (I can imagine this is something Trump wouldn't say, yay), but really that checkbox could just show state and remain grey, not showing an illusion of a setting that "must" be tampered with.
    When I look into my Intel wireless adapter settings, mixed mode protection is set to "CTS-to-self enabled" and all greyed out.
    This basically is not a setting you are supposed to set, unless you use Wireless mode : Legacy, but that mode is just redundant, as it restricts you to 20MHz bandwidth only.

    So long story short, aka the long awaited TL;DR :

    Wireless Mode : Legacy - allows setup (not sure if it does anything, didn't test)
    Wireless Mode : N only - of course off, what would you use it for, anyways?
    Wireless Mode : Auto - it can be ticked off, but ticks itself back on and it is true (tested with a 11b device), this mode makes the "Legacy" useless, as here you can set 40 MHz bandwidth (bonded channels), so what is the point of legacy? Using 11g devices without 11b protection or what?

    I guess in case of "Auto", 11b and 11g devices communicate solely on the control channel and this is the one protected, but I guess it doesn't matter, beacause the older devices just ignore (are not aware of) the extension channel.

    Then the performance of today's consumer AP HW is so high, there's no reason to not let 802.11b devices on your network. If you have many modern clients, you just switch to N-only mode, but with no real performance benefit even in that case (and possibly trolling someone's legacy setup).

    Sometimes it is just easier to go there, get hands dirty and test it, like I did :)

    So this is my setup for RT-AC66u :

    Wireless Mode : Auto
    b/g protection : True (default, can't be changed)
    Channel bandwidth : 40 MHz

    If using 40 Mhz, try to use (whenever possible):
    Control channel: 1
    Extension channel: above,
    as channels 12 and 13 (channel 13 used in: 13+below or 9+above) are rubbish (unless you only need a small coverage perimeter), also if you are in Europe and people around you adhere to another ancient, so 2000 "pro tip" of 1-6-11 (instead of 1-5-9-13), you might get a lot of noise from channel 6, that's why you might want your beacon on 1 and only the extension on 5, not vice versa.

    This is going strong; even with an 802.11b device on the network the .11n devices are up to highest expectation.
    Last edited by a moderator: Feb 14, 2017
  8. sfx2000

    sfx2000 Part of the Furniture

    Aug 11, 2011
    San Diego, CA
    I'm a former member of the IEEE 802.11 and 802.16 working groups, along with IETF and 3GPP2/3GPP - I've been there, done that, designed AP's and customer premises equipment, and co-founded a startup regarding MESH networking.

    So yes, I do know what I'm talking about.

    Reason why we want 2.4GHz to be B/G/N has to do with the concept of "do no harm" to adjacent networks - back in '07-'08 time frame, it was a pretty ugly mess in the IEEE 11n working group, and pretty much split across camps...

    (That's why we now have greenfield 11n mode, as a result of the compromises done back then) - 11n in greenfield can be fast, but all one needs is an adjacent BSS that is legacy, and this puts your WLAN/BSS into Greenfield Protection Mode, irregardless of whatever settings you do in the AP settings...

    Mixed Mode will be faster in those conditions than Greenfield with a legacy network present.
    buddyp likes this.
  9. sfx2000

    sfx2000 Part of the Furniture

    Aug 11, 2011
    San Diego, CA
    2.4GHz compat and interop needs to be taken seriously - the case above suggests this...

    Been there myself with the Nokia N770 Internet Tablet...


    Nice little device - but when it hit an 802.11n (HT) beacon - the WiFi chip itself would crash - not crashing the device, but the HT epigrams on the Beacon would run the 802.11 parser in the WiFi firmware off the deep end with an exception error...

    And it just needed to be a 802.11n (HT) network somewhere in the vicinity - not just the BSS local to the device.

    Realtek has some issues with their 11ac chips when running into Broadcom and Marvell - not for the same reason, but they can get confused with VHT info in 2.4GHz - they don't crash, but they will have serious issues with association and link maintenance - which results in a bad user experience...

    I'm still pretty much in the camp of keeping 2.4GHz as simple as possible, not just for one's own WLAN (BSS) but for adjacent WLAN's - so the B/G/N guidance is fair - and disabling Turbo/Nitro/Up to 600Mbps/whatever stuff isn't part of 11n is a good idea.

    I've got a dual band network, as many do here - and 2.4GHz is still relevant - it's the backstop to my 5GHz, and I want it to be as stable as I can make it - not just for my WLAN, but for my neighbors...
  10. ascanio1

    ascanio1 Regular Contributor

    Apr 24, 2012
    So, in 2017, what is best setting for the "b/g protection" setting, considering the following:
    A)Device is running as an AP, not router
    B) I have no neighbours (isolated farmhouse)
    C) I have other networks in the house (other rooms)
    D) I have no 802.11b clients, two 802.11g clients and many 802.11n and 802.11ac clients

    Thanks in advance for sharing your time and expertise.

  11. Maestro

    Maestro New Around Here

    Aug 25, 2017
    I couldn't get my ring video doorbell set up on an Asus router - ticked and unticked b/g protect thinking that it might be the cause. Tinkered with the 2.4ghz settings for quite a long time. Finally found out the problem - the ring video doorbell doesn't seem to like bands above 10. So I knocked it out of auto and switched to band 6... Problem solved. Shame you can't restrict auto to not change bands above 10 so that it only auto selects between bands 1-10. Totally irrelevant to this post I know but the b/g protection seemed to take me down memory lane.
  12. sfx2000

    sfx2000 Part of the Furniture

    Aug 11, 2011
    San Diego, CA
    Probably still yes... doesn't hurt/doesn't help... no harm in keeping it enabled.
    Maestro likes this.

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