Article Discussion: How Many SSIDs Is Too Many?

[zakoh]

http://www.smallnetbuilder.com/basi...751-snb-answer-guy-how-many-ssids-is-too-many


I have several reasons for using separate SSIDs for 2.4 and 5GHz WLANs. I don't know how valid they are. My biggest fear is that the client will not always choose the right BSSID for the best performance. For example, it's quite common to have a situation where the signal strength of a 2.4GHz radio is stronger than the 5GHz radio at a distance, however the client will achieve a faster link rate with the 5GHz radio due to better 802.11ac modulation, wider channel, and all that, so using BSSID of the 5GHz radio should be preferred unless the latency is worse. But how will Windows 7 behave in this situation, or Linux, or iOS? I don't know and don't have time to test this, so I prefer to have different SSIDs, everyone connects to SSID with the 5GHz radio, unless the range is too long, resulting in slow speed or bad latency, or the client hardware is 2.4GHz only.

Another issue I have observed is that on one machine the 2.4GHz wireless performance drops sharply when I have a USB3 hub connected its expresscard USB3 adapter (probably unshilded). Again, I need to have a way to ensure that this client always uses the 5GHz WLAN. I am not sure and I haven't tested how would Windows or Linux behave under such circumstances.


PS: I hope that some time soon someone will also write an article explaining the channel selection decision when you operate multiple APs.

 

[L&LD]

It would be nice to know who SNB Answer Guy is.

With regards to the article, I disagree with using a single ssid by default. More headaches for the network administrator vs. separate ssid's and usually not fixable (device dependent).

 

[Nonprofit]

This doesn't address the issue of sticky clients (or maybe it did and my reading comprehension sucks today), but that is the main reason I usually consider keeping multiple SSIDs.

It comes down to what I find more annoying... having to manually join a new AP when I walk from one area to the next, or having to reset the wifi on my device to force it to jump to the closer/stronger AP because with one SSID it sticks to the one it was just on instead.

 

[SNBAnswerGuy]

It would be nice to know who SNB Answer Guy is.

With regards to the article, I disagree with using a single ssid by default. More headaches for the network administrator vs. separate ssid's and usually not fixable (device dependent).

Network Admins know their network, and can always track errant AP's and/or Devices by the BSSID of the AP.

Easier to debug, not more difficult - just need to use the best tools for the task at hand.

 

[SNBAnswerGuy]

This doesn't address the issue of sticky clients (or maybe it did and my reading comprehension sucks today), but that is the main reason I usually consider keeping multiple SSIDs.

It comes down to what I find more annoying... having to manually join a new AP when I walk from one area to the next, or having to reset the wifi on my device to force it to jump to the closer/stronger AP because with one SSID it sticks to the one it was just on instead.

A "sticky" client is a bug perhaps, or a setting in your driver for roaming aggressiveness...

Case in point - NetworkManager on Linux, which in many cases confuses the issue of SSID == BSSID, and as a result, will not handover many times, and worse yet, not associate with another BSSID, even though the SSID is exactly the same.

How is that not a bug?

 

[SNBAnswerGuy]

I have several reasons for using separate SSIDs for 2.4 and 5GHz WLANs. I don't know how valid they are.

They may be perfectly valid reasons - every network plan is different - the article is a general advice/guidance piece - suitable for most, but some people have very specific reasons why they want to have more granular control of the network.

All good - if the article helps, that's great - not everyone is a WiFi networking expert, and this was the target audience.

My biggest fear is that the client will not always choose the right BSSID for the best performance. For example, it's quite common to have a situation where the signal strength of a 2.4GHz radio is stronger than the 5GHz radio at a distance, however the client will achieve a faster link rate with the 5GHz radio due to better 802.11ac modulation, wider channel, and all that, so using BSSID of the 5GHz radio should be preferred unless the latency is worse.

Different drivers/devices and operating systems have their own thresholds/curves for making decisions on which BSSID to join - some do it well, others don't.

But generally, they make the right decision - and it may not be obvious as to why, but in real time, it may prefer a really great 2.4GHz BSS over a not-so-good 5GHz BSS - and depending on the AP capabilities, it could be something as simple as a QBSS report that suggests that the 5GHz channel is congested and the 2.4GHz is not.

But how will Windows 7 behave in this situation, or Linux, or iOS? I don't know and don't have time to test this, so I prefer to have different SSIDs, everyone connects to SSID with the 5GHz radio, unless the range is too long, resulting in slow speed or bad latency, or the client hardware is 2.4GHz only.

Again, some driver implementations actually do score connections, some don't.

Another issue I have observed is that on one machine the 2.4GHz wireless performance drops sharply when I have a USB3 hub connected its expresscard USB3 adapter (probably unshilded). Again, I need to have a way to ensure that this client always uses the 5GHz WLAN. I am not sure and I haven't tested how would Windows or Linux behave under such circumstances.

That's a known issue with USB3 signalling rates and the ISM band - the problem affects WiFi and Bluetooth - WiFi more so, as the interference noise is broadband, Bluetooth can and often does, plan it's hops around interference.

Better cables can help, but it won't totally mitigate the interference - I suppose the good news is that the interference is generally localized to the USB3 device chain and any WiFi radios in close proximity.

PS: I hope that some time soon someone will also write an article explaining the channel selection decision when you operate multiple APs.

Looking into that.

Anyways, all comments are appreciated.

 

[L&LD]

Network Admins know their network, and can always track errant AP's and/or Devices by the BSSID of the AP.

Easier to debug, not more difficult - just need to use the best tools for the task at hand.

Nobody I know is a 'Network Admin' as you intend them. Much more difficult for a normal human to track anything down.

Btw, you ignored who SNBAnswerGuy is? If you're writing articles, I think we should know your name?

 

[SNBAnswerGuy]

Nobody I know is a 'Network Admin' as you intend them. Much more difficult for a normal human to track anything down.

Actually, the tools can be as simple as what we all use - InSSIDer is a good example, as it does show the MAC Address of the AP - the "BSSID" for each member of the ESS in a dual-band or multiple AP Wireless LAN, and then you can track it back from there.

Windows, on the command line, same thing - netsh is a great tool, and it's free - bundled with Windows.

Linux - same thing, between ifconfig and iwconfig, and lots of tools like Kismet, etc. - all free

Even Mac's have some great GUI and command line tools to debug networks - spend a couple of dollars, and there's even better tools in the Mac App Store.

iDevices - e.g. iPhone/iPod/iPad - there's a WiFi scanner built into the Airport utility - good stuff, and guess what - free.

So if you're building out a wireless LAN, and only depending on SSID's to differentiate where your clients are, then you're missing out on the real power of 802.11 WiFi and what it can do for you, and all of the users/devices on your network.

 

[DavidB]

I'm not a 'Network Admin' but have what I think is a basic understanding how WiFi works. So here's my setup:
3 story house.
Basement has a FIOS 802.11N single radio router, and since it's FIOS I'm letting it be the "master" (DNS, DHCP, Gateway, etc.) of my network (I have the whole home DVR TV package so all TV tuning takes place in one VMS box and the 3 remote TV's have client VMC boxes that talk MOCA to the VMS via that same router). I'm assuming I need to let the FIOS router be the "master" because of how VMS/VMC works (all four show up on my network, with IP's) to get me TV/DVR on all 4 TV's. SSID: WIRELESS, Channel:1
1st floor has a Edimax dual band dual radio 802.11AC router, wired 1000TX to the FIOS router, operating in "Access Point" mode. 2.4GHz radio SSID: WIRELESS, Channel: 6; 5GHz radio SSID: WIRELESS5, Channel 40
2nd floor has a Edimax dual band dual radio 802.11AC router, wired 1000TX to the FIOS router, operating in "Access Point" mode. 2.4GHz radio SSID: WIRELESS, Channel: 11; 5GHz radio SSID: WIRELESS5, Channel 48
My WPA2 key is identical for all SSID's/radios in all three routers.
Wireless clients are a pretty common mix of relatively recent model Apple and Android smartphones and tablets, 1 Chromebook, 1 Win7 laptop, 3 Chromecast, and 2 FireTV. All other PC's and my 3 Playstations are wired.
I selected the channels to use on each router by just walking around the house with a tablet using "WiFi Analyzer", narrowed my choices down to 1/6/11, and configured each router to whichever of the 3 channels had the fewest other routers showing up in scans from where the router sits. Nowhere in my house or even outside around the house are there any other 5GHz routers seen.
I don't notice any abnormally low "speeds" anywhere in the house from any wireless device, nor does any wireless device ever seem to suffer any difficulty getting "connected".

I guess my questions to the SNBAnswerGuy are two:
1. Am I doing anything obviously wrong in this setup?
2. Is there something I could change that would make it "better" (let the AP's all auto-select channels, make my 5GHz SSID's the same as my 2.4GHz, etc.)?

Thanks. I've learned more about networking from browsing this site than I've learned from any other source.

 

[SNBAnswerGuy]

I guess my questions to the SNBAnswerGuy are two:
1. Am I doing anything obviously wrong in this setup?
2. Is there something I could change that would make it "better" (let the AP's all auto-select channels, make my 5GHz SSID's the same as my 2.4GHz, etc.)?

Reviewing what you posted, it looks like you've done a great job with your home network. You've done all the "right" things, more AP's vs. trying to go with more power/antenna gain, putting the AP's where the traffic generally is, and it sounds like you've worked through many of the challenges presented by a "mandatory" carrier Modem/Gateway, which is needed for the television set top boxes to function correctly.

Outside of the wireless network, the three Playstations present their own problems - why is it that Sony and Microsoft have so many challenges with their network stacks is beyond me - they definitely don't like NAT's, which is odd, as most people put their consoles behind a Router/AP, and NAT is just part of it.

2.4GHz - I see you're using all three of the primary channels, you might be able to get away with Ch 1 in the basement, 11 on the first floor, and 1 upstairs, otherwise leave it as it is.

5GHz - with 11ac, there's really only two channels that many devices can work with in 80MHz depending where one is in the world - but in North America.. I think you're ok where you are there - might consider putting the 1st floor on 149 and see if that has any improvement.

 

[SNBAnswerGuy]

Nobody I know is a 'Network Admin' as you intend them. Much more difficult for a normal human to track anything down.

We, as a collective, may not have CCNA, CWNP, MSCE, etc certificates on the wall, but in the home, we are functionally the admin of our networks. So if one is reading the forums here, or researching and perusing the reviews/articles on the primary SNB site, one is literally a network admin.

The SNBAnswerGuy series - we're not full time admins, we have day jobs, families, and games to play and movies to watch, so the series is to capture some basic general guidance when we design and deploy our home networks. Once that's done, then one can tune things to polish up the rough bits.

It's the KISS principle - Keeping It Simple Sailor - We're putting more and more on to our home networks, when one stops to consider, in a typical household, most people will have at least two screens each, sometimes three, and then the general purpose items - so a family of four can easy have over 20 nodes on the wireless LAN. How we use the networks has also changed, so again, we're putting this series together to make the most of the investments we made over time.

 

[Nonprofit]

A "sticky" client is a bug perhaps, or a setting in your driver for roaming aggressiveness...

Case in point - NetworkManager on Linux, which in many cases confuses the issue of SSID == BSSID, and as a result, will not handover many times, and worse yet, not associate with another BSSID, even though the SSID is exactly the same.

How is that not a bug?

It might be a bug. But if so, it is a bug that every client I've ever worked with has. Linux, Windows, MACs, and especially iDevices. My personal iPhone is terrible at letting go of weak signals to jump to stronger ones. Even in my own house, where there are two APs with 1 SSID. I walk from one side of the house to the other and the only way to get it to jump to the stronger signal is to turn the phones wifi off and then back on again... or wait for like 5 minutes when it will finally figure it out itself.

 

[htismaqe]

It might be a bug. But if so, it is a bug that every client I've ever worked with has. Linux, Windows, MACs, and especially iDevices. My personal iPhone is terrible at letting go of weak signals to jump to stronger ones. Even in my own house, where there are two APs with 1 SSID. I walk from one side of the house to the other and the only way to get it to jump to the stronger signal is to turn the phones wifi off and then back on again... or wait for like 5 minutes when it will finally figure it out itself.

I don't have this problem at all and we have Windows 7, OS X, iOS, and Android. Some of the devices have harder times with it but for the most part, it works just fine.

In fact, you seem to stress that your iDevices are the WORST at AP hopping. In my house, my iPhone 6 is the BEST at doing it.

 

[SNBAnswerGuy]

It might be a bug. But if so, it is a bug that every client I've ever worked with has. Linux, Windows, MACs, and especially iDevices. My personal iPhone is terrible at letting go of weak signals to jump to stronger ones. Even in my own house, where there are two APs with 1 SSID. I walk from one side of the house to the other and the only way to get it to jump to the stronger signal is to turn the phones wifi off and then back on again... or wait for like 5 minutes when it will finally figure it out itself.

Sorry to hear that - here's a kitten - feel better?

One of the key things in deploying WiFi networks is not how many AP's, but where they're located - you want to give a decent amount of overlap when using two or more discrete AP's - you might be in a situation where you have gaps in coverage.

For your iDevice - reset the network setting in Settings > General > Reset Network settings, and then start over - might help.

What I can say, based on your observations, is that using Unique SSID's will exhibit the same behavior - so maybe check your SSID settings, along with WPA2-AES keys, and let's make sure that all the keys are common across the AP's.

 

[Nonprofit]

It is possible that I have higher expectations for wireless roaming, but the same experience is reported to me by staff and clients. And, regarding iDevices, if you go over to the Apple forums you will read dozens and dozens of posts about this. There, it seems widely accepted that iOS in particular is terrible at this.

This is why companies like Ubiquiti have come up with solutions like Zero Handoff, because people are not satisfied with how this works.

It is very easy to confirm. From a machine with an ethernet connection to the network, start a ping to a machine connected to wifi. Now walk around the office/campus/large home with that wifi connected device. Back on the machine doing the pinging you will see connection drops for large chunks of time until the machine renegotiates and hops to the new AP.

Overlap of APs doesn't seem to matter, because the client sticks to the AP it is on until the signal is so weak it drops. THEN it re-searches, re-connects to whichever signal is strongest. So if AP 1 and AP 2 are overlapping, and you walk from 1 toward 2, the device will not switch until you walk completely out of range of AP 1 and the connection drops. I've confirmed this via the ping test above.

 

[Dr Strangelove]

I have two routers (ASUS RT-AC66U and Linksys E4200v1) 15metres apart on a home LAN with two SSID on each router, one for 5GHz(802.11n/ac) and one for 2.4GHz(802.11n/g).

I have in house DNS and DHCP servers(Linksys E4200v1) with DHCP MAC to name pre-mapped, with unknown DHCP devices blocked.

My five Android devices have no problems 'flipping' between the two routers.
Even my old Sony Xperia X10 802.11g phone with Android v2.3 switches to the better router without problems.

With good 5GHz and 2.4GHz coverage, I never want 5GHz devices using 2.4GHz, thus the two SSID.

As already mentioned, it's the channel allocation, especially on 2.4GHz with multiple routers that peaks my interest. At the moment I have both APs using 20MHz 2.4GHz SSID on channel 13. (being nice to neighbours)

The above seems to work OK, but one wonders if having one SSID on the same channel on different routers (same LAN) creates additional noises and weakens the signal.

My 2.4GHz band is too crowded to be able to do any control tests, that's why I'm living on channel 13 (valid in this country). A quick test on 40MHz 5GHz using channel 36 with 15metres between routers didn't indicate any problems.

As I'm the only one using 5GHz at the moment, my 5GHz SSID is on channels 36 on one router and 149 on the other.

Maybe channel allocations is another topic.

 

[SNBAnswerGuy]

It is possible that I have higher expectations for wireless roaming, but the same experience is reported to me by staff and clients. And, regarding iDevices, if you go over to the Apple forums you will read dozens and dozens of posts about this. There, it seems widely accepted that iOS in particular is terrible at this.{/quote]

Actually it is not - if you have links with regards to iOS (Apple, not Cisco) roaming issues, please feel free to cite them with the appropriate links, otherwise this is your opinion only - which is fair, and I respectfully disagree

This is why companies like Ubiquiti have come up with solutions like Zero Handoff, because people are not satisfied with how this works.

UBNT's Zero-Handoff hasn't worked very well compared to what Cisco and Aruba have done, along with Meru and Xirrus.

Many customers there have been disappointed as a promised feature that didn't deliver. Buggy AP implementation - file a bug with them perhaps.

It is very easy to confirm. From a machine with an ethernet connection to the network, start a ping to a machine connected to wifi. Now walk around the office/campus/large home with that wifi connected device. Back on the machine doing the pinging you will see connection drops for large chunks of time until the machine renegotiates and hops to the new AP.

Be more specific - you're talking about client behavior, but not about the network parameters - the Article was focused on the network side for the casual user.

Overlap of APs doesn't seem to matter, because the client sticks to the AP it is on until the signal is so weak it drops. THEN it re-searches, re-connects to whichever signal is strongest. So if AP 1 and AP 2 are overlapping, and you walk from 1 toward 2, the device will not switch until you walk completely out of range of AP 1 and the connection drops. I've confirmed this via the ping test above.

Yes, network layout is important.

In any case, your argument against Common SSID's, where you suggest it's not good - it doesn't hold weight, as when using unique SSID's with your WLAN, the client will camp until the signal is lost.

period, end, over and out...

 

[SNBAnswerGuy]

I have two routers (ASUS RT-AC66U and Linksys E4200v1) 15metres apart on a home LAN with two SSID on each router, one for 5GHz(802.11n/ac) and one for 2.4GHz(802.11n/g).

I have in house DNS and DHCP servers(Linksys E4200v1) with DHCP MAC to name pre-mapped, with unknown DHCP devices blocked.

You probably have too many routers/AP's - sometimes less is more...

My five Android devices have no problems 'flipping' between the two routers.
Even my old Sony Xperia X10 802.11g phone with Android v2.3 switches to the better router without problems.

With good 5GHz and 2.4GHz coverage, I never want 5GHz devices using 2.4GHz, thus the two SSID.

One would think that best service is always better - 2.4GHz isn't bad...

2.4GHz for Range
5.0GHz for Speed

And good enough is good enough.

As already mentioned, it's the channel allocation, especially on 2.4GHz with multiple routers that peaks my interest. At the moment I have both APs using 20MHz 2.4GHz SSID on channel 13. (being nice to neighbours)

In any location, keeping the 2.4GHz AP's on a single channel is downright neighbor friendly - 802.11 b/g/n is normally 1 thru 11, but some countries do allow for 12, 13, and 14 with some restrictions.

The above seems to work OK, but one wonders if having one SSID on the same channel on different routers (same LAN) creates additional noises and weakens the signal.

It's less of an issue than many would believe - two AP's on the same channel will coordinate - it's when repeaters are involved that capacity can take a hit.

My 2.4GHz band is too crowded to be able to do any control tests, that's why I'm living on channel 13 (valid in this country). A quick test on 40MHz 5GHz using channel 36 with 15metres between routers didn't indicate any problems.

How do you know it's too crowded? 802.11n is much more friendly to co-channel/adjacent channel interference than 802.11 b/g was - just because you see an AP there, doesn't mean it's a jammer - sometimes it is, but consider that the 802.11 Beacon Frames are sent with very high coding gain compared to the traffic frames. This is so that adjacent/overlapping BSS's are aware of them, and so that one can find them within the WiFi client application.

As I'm the only one using 5GHz at the moment, my 5GHz SSID is on channels 36 on one router and 149 on the other.

Maybe channel allocations is another topic.

Moving to 5GHz is always a good option, but sometimes this isn't possible.

Recommendation on channel allocations - noted, seems like folks are interested here.

 

[htismaqe]

And good enough is good enough.

All too often this gets overlooked here.

It's like trying to talk about the merits of owning a Chevy Malibu on a Porsche user forum.

 

[sfx2000]

All too often this gets overlooked here.

It's like trying to talk about the merits of owning a Chevy Malibu on a Porsche user forum.

Don't know about Malibu's - but a V6 Camry/Accord can shame a Porker in a straight line, and even on the curves, they can account for themselves - they're surprisingly quick... I'd take the Honda over the Toyota, but that's me...

Disclaimer, I own an Acura TSX... which is a fine automobile...

I think the article is looking for a general solution - there will always be exceptions - and we in the forum tend to dwell on exceptions and think those xceptions are the general gist of things.