Guest Networks

[Darknessrise]

Hello, I just bought a new gateway which supports 8 SSIDs on the 2.4 GHz band.
I was curious whether or not the 7 guest networks interfere with each other? Could someone explain how the guest networks work in terms of the actual signal?

Say I enabled all 7 guest networks along with the main network. Would all 8 networks be the same "signal" and the router would not have to work harder to provide the broadcasts? or are the guest networks considered a whole new router in terms of what actual "signal" is used?



So, to sum up my rambling...
Are guest networks considered as if they were:
1) 8 separate routers all at the same place broadcasting
2) One router that just broadcasts the name of the guest networks that travels with "signal" of the primary network.

Reason I ask is because I don't want to be bombed by wireless radiation if it's actually like I have 8 routers next to me.

 

[stevech]

Guest SSIDs of course use the same RF hardware.

 

[sfx2000]

More SSID's from the same radio is more overhead, so only run what you must...

 

[CaptainSTX]

The trade off is that by running multiple SSIDs you may discourage other nearby WiFi users from using the channel that you are on. If they don't look to closely at the details of what they find on inSSIDer they will think your channel with all the SSIDs is busier than it really is. This is particularly helpful if you have someone nearby running 40 Mhz on the 2.4 Ghz band.

 

[sfx2000]

Again - not a good idea if you want to keep decent throughput on your WLAN.

Additional SSID's on the same channel are broadcast at the lowest rate - each beacon frame adds additional overhead, and this is time not spent sending actual data. In the case of 802.11n, beacon frames are fairly large.

A single SSID adds about 3-4 percent overhead - adding a guest SSID adds the same amount (which is why if you don't need guest SSID's, don't use them) - lighting up all 8 - that would take up over a 1/4 of your total bandwidth on that AP alone.

This is also the reason why I strongly suggest that in a multiple AP environment, use a single common SSID - 2 AP's with 2 SSID's, you're now at 12 percent overhead. Add guest SSID's, and it's even worse.

Always work to optimize the WLAN - and make the right choices.

(another hint - never set 2.4Ghz to 802.11n only - this is greenfield mode, and every transmission must do a CTS to self, which means even more overhead - leave it in mixed mode (B/G/N) for best performance)

 

[sfx2000]

Oh, the reason I don't mind the overhead is because I don't use my wireless that much. I probably won't use all 8 SSIDs because I think I'm returning the device anyway. I'll be sticking to only two SSIDs now after the fact.

Thanks for the tip about the N only vs. mixed. I'll take that into consideration.

One doesn't just impact one's own network, it impacts everyone else on the same channel within range of your AP

 

[L&LD]

sfx2000, you bring an interesting point regarding mixed and strictly 'N' mode.

Wouldn't a single g device slow down the network more than restricting to 'N' clients only? Of course, I'm assuming on a guest network (rather than a more restricted home only situation).

Have you done tests to show how much difference this makes? Just curious if it's 1% or 10%, for example.

Thanks for any info.

 

[sfx2000]

sfx2000, you bring an interesting point regarding mixed and strictly 'N' mode.

Wouldn't a single g device slow down the network more than restricting to 'N' clients only? Of course, I'm assuming on a guest network (rather than a more restricted home only situation).

Have you done tests to show how much difference this makes? Just curious if it's 1% or 10%, for example.

Thanks for any info.

CTS-to-Self can add about 20 percent overhead - and it's one of the more efficient protection mechanisms.

One thing to keep in mind - the channel is a shared medium - so while one might have 11n clients and AP's on the WLAN, any traffic on the channel, and this includes adjacent overlapping WLAN's - if there is 11b/11g traffic on the channel, the protection modes will kick in...

11g clients will get hammered more than 11n will, as one 11n has the channel, it can use frame aggregation to keep the channel until frames are done... remember, only one node can transmit on the channel at any given time.

sfx

 

[L&LD]

Always work to optimize the WLAN - and make the right choices.

(another hint - never set 2.4Ghz to 802.11n only - this is greenfield mode, and every transmission must do a CTS to self, which means even more overhead - leave it in mixed mode (B/G/N) for best performance)

sfx2000,

I have just tested the above (set my RT-N66U to Auto, not 'N' only) and found a significant speeding up of my network. (I tested running a file sync on a 100K file folder with freefilesync specifically).

Thank you very much!

To put a number to this: even when the folders were 'synced' the comparison was taking just under 2 minutes. Now it is finishing this in around 35 seconds.

While the overhead added is 'only' 20% by forcing 'N' only mode - it seems with such small transfers (as when comparing files like my 'test' does above) the performance increase is much, much more.

Additionally, there is less variation in the upload/download traces from what I have seen with 'Auto' enabled.


What other ways is there to optimize the Lan (wired and wireless) that you can share? Maybe you have written a tutorial already?

(A search didn't find anything specific or thorough though)?


Does anybody else have any other tweaks to share?


Wishing everyone at SNB a Happy New Year!

 

[thiggins]

To add to sfx2000's post about "Greenfield mode". It seemed like a good idea at the time, but adds significant overhead.

Greenfield mode was not carried into 802.11ac.

 

[L&LD]

To add to sfx2000's post about "Greenfield mode". It seemed like a good idea at the time, but adds significant overhead.

Greenfield mode was not carried into 802.11ac.

Does that mean with any AC class router we can specify the fastest mode(s) only without penalty?

I'll be sure to try that when I'm next near an AC class router.

Oh; will that also mean for 2.4GHz band the 'greenfield' mode will still be effective on the AC routers?

Thanks for the puzzles to figure out and (keep) testing.

 

[CaptainSTX]

The trade off is more overhead vs. less interference from competing APs that choose to use the same channel that you are on. I only activate the guest networks to encourage people that insist on using 40 Mhz channels to move to the other end of the spectrum.

In my location I pick up 28 - 35 SSIDs. If I can encourage some of them to move away from the channel I would like to use it probably has a positive impact on my through put.