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Mon, Mar 24, 2014 10:09 AM

Adavantages and disadvantages of using multiple SSIDs

In a old thread (that I only noticed recently) it was mentioned that each SSID uses 2.3% of bandwidth. Not seen that figure mentioned before.
I use a lot of SSIDs (12) to segregate, assign and control different groups of school laptops. If this is correct I would try to use far fewer.

Any comments about the BW implications per SSID or other reasons for/against numerous SSIDs welcome. Thanks.

Responses

Champion

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202 Messages

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3K Points

7 years ago

Funny, I just noticed that post too.

..and I just added a comment to this thread:
https://forums.ruckuswireless.com/ruc...
that might help if you need to do a *lot* of SSID consolidation but still want separate VLANs.

683 Messages

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11K Points

7 years ago

12 SSID's is taking about 25% of your available bandwidth (which increases a bit with the number of clients the AP can hear), so yes, it's definitely significant.

368 Messages

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5.6K Points

7 years ago

That's one reason why you need to disable 11b ASAP. If you use OFDM only you increase the minimum speed of beacons and other management frames.

Champion

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202 Messages

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3K Points

7 years ago

Ah. Good thinking..
But do you need/want to increase the bss-minrate as well?

What's the lowest 11b speed vs the lowest non-11b speed?

How much of a speed gain can you expect from ditching 11b support and is the speed gain directly related to the minimum "PHY" rates or ...
How much overhead is there that's strictly related to the 11b protocol itself? (as opposed to the PHY rate?)

368 Messages

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5.6K Points

7 years ago

Lowest 11b is 1Mbps. Lowest OFDM defined for 11g is 6Mbps. You can increase that, usually to 12 or 24 since those are the basic rates 11g must support.
But you need to be careful. Raising rates doesn't actually decrease cell size since the preamble is always sent at minimum rate (6Mbps) regardless of the rate you set.

The least you could do is disable 11b. Do it now and thank me later! Then try raising minimum rate and see how far you can go with that. If you start running into problems throttle down.

I haven't tested with the new FW (9.7), but I think there is a small bug in it where if you set a rate of 12 or other and want to change back to 6 you won't be able to do it. It will notify you that 6 isn't supported, but you can set it to 5,5Mbps which is one of 11b rates which is just ridiculous.

Champion

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202 Messages

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3K Points

7 years ago

So... configuring ofdm-only would give you one sixth of the airtime overhead per SSID?
That would give you about 4% overhead for 12 SSIDs.
Is that right?

6 Messages

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140 Points

6 years ago

please..someone to tell me...

i have 1AP with 6 SSID.. it means 6 RF signal ??
therefore, it means AP causes his own interference ??
its similar to have 6 antenas on same place radiating with same channel and power.???
devices( as a laptop) receive 6 signals and therefore interference wich comes from one antena????

regards......!!!!!
Brand User

Former Employee

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2.6K Messages

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44.8K Points

6 years ago

Depending on your authentication methods, you could serve 12 sets of clients with one SSID, and pass a VLAN attribute back from your AAA server to say which of 12 different VLANs to put the user into, with a dynamic VLAN feature.