I'm very used to dealing with 802.11b but not so familiar with faster flavors. If I were to open up one access point to users on 802.11b but held out another access point for faster users, could that work? I'm thinking in terms of getting a 16Mb Comcast connection and would like to be able to get higher throughput on at least one AP. In other words, not allow slow connections on the faster AP so everyone wouldn't be slowed down to 802.11b.
802.11 stuff
Jul 07, 2009
39 Replies
On Tue, 07 Jul 2009 19:41:02 -0400, Rôgêr wrote in :
Yes it would work. Put them on different minimally overlapping channels (1, 6, 11).
Thank you, pretty much what I thought. Now, is there an AP available that I can program to not allow slow (802.11b) connections? I know I can filter by MAC and so forth, just wondering if there's an AP that makes this "fallling off the log" easy.
Sorry if this is duplicated, TB tried to send but reported an error.
I would have thought that all b/g AP's allow you to configure them for 'b', 'g', or both.
On Wed, 08 Jul 2009 01:27:25 -0400, Rôgêr wrote in :
Many will allow you to set B-only, G-only, or B+G. I'd personally: * Set the G access point for G-only * Leave the B access point at B+G * Use different SSID on the two access points, so clients can select which one they connect to * Likewise use different WPA-PSK keys In general, filtering by MAC is not a good idea, adds no real security, and is a PITA to administer.
very hard to find b and g only nowadays, many have b/g/n now....
On Wed, 8 Jul 2009 13:22:43 -0400, "Peter Pan" wrote in :
Lots of b and g products on the market.
Only *draft* n -- there are no actual n products yet.
I would tend to agree. I don't think I have ever seen a b/g device that didn't have a "g or b only" setting.
An 808.11g AP has to accept and wait for 802.11b traffic present on the
2.4GHz band. And any 802.11b AP or 802.11b client will not be able to "see" the 802.11g AP or 802.11g clients or the 802.11g traffic. So the end result will be slow traffic on the 802.11g AP.Better would be using an 802.11a AP, which uses the 5GHZ band and does not interfer with 2.4GHz traffic for your fast connection.
On Thu, 9 Jul 2009 01:24:31 +0200, snipped-for-privacy@hotmail.com (Axel Hammerschmidt) wrote in :
Usually easier and cheaper to use a minimally-overlapping 2.4 GHz channel.
Not in this case. See fig 12-7 "Channel separation in 802.11 DS networks" on page 259 in "802.11 Wireless Networks" 2nd ed, by Matthew S Gast. There's overlap using channels 1 and 11.
On Thu, 9 Jul 2009 02:33:48 +0200, snipped-for-privacy@hotmail.com (Axel Hammerschmidt) wrote in :
Not significant.
snipped-for-privacy@hotmail.com (Axel Hammerschmidt) wrote in news:1j2kbgm.wrcfmo1gop32cN% snipped-for-privacy@hotmail.com:
Doesn't that all depend on whom is using the wireless network, and what hardware they have ? Do they have client hardware that is '802.11a- capable' ?
Yes.
If an AP is set for 802.11g only, it will ignore 802.11b traffic as noise. It won't do CTS/RTS with it, which is part of what appears to slow down the 11g traffic.
5GHz does not penetrate walls and other obstacles as well as 2.4GHz.Steve
Wrong figure.
This should bring you to fig 12-5. There you will see, that the spread is greater than 22 MHz. Scroll down to fig 12-7. Although weak, when the
802.11b and 802.11g APs are close to each other, as will be the case here, there will be interference.Steve Fenwick:
Scroll back up to Protection.
Not so. In theory, 802.11b/g will have marginaly longer range.
On Thu, 9 Jul 2009 13:22:37 +0200, snipped-for-privacy@hotmail.com (Axel Hammerschmidt) wrote in :
From your source:
802.11b specifies that a 25 MHz (5 channel number) spacing is sufficient. Figure 12-7 shows the spectral mask of transmission on the so-called non-overlapping channels (1, 6, 11).Figure 12-7 shows the amount of overlap and interference between channels 1 and 11 to be not significant.
Which is what I said--put the AP in 802.11g radio only, and protection will not be enabled.
Which is what I said--2.4GHz (the band used for 802.11b/g) has better range (and wall penetration) than 5GHz.
Steve
From your posting:
Message-ID:
"Put them on different minimally overlapping channels (1, 6, 11)."
And:
Message-ID:
"... a minimally-overlapping 2.4 GHz channel."
The Navas Group, a rock 'n' roll band?
On Fri, 10 Jul 2009 01:37:43 +0200, snipped-for-privacy@hotmail.com (Axel Hammerschmidt) wrote in :
Apparently you have a reading comprehension problem.
Not to mention a civility problem.
Sure. I have 3 customers doing exactly that. 2 businesses and a coffee shop. The trick is to use different channels (1, 6, and 11) so that they don't interfere with each other. If you try to handle both
802.11b and 802.11g on a single access point, the 802.11b users will slow everyone else down. However, with 2 access points, with one set to 802.11g speeds only, there's no slow down. There's less of a need for this today, where just about everything that enters the business of coffee shop can do 802.11g. However, that was not the case 3 years ago, when 802.11b devices were still appearing.Well, do you have any 802.11b only client computahs or devices? If not, then just turn off 802.11b and set it for 802.11g only. If yes, setup a 2nd 802.11b device as an access point, and turn it on only when necessary.
Incidentally, if you plan to shovel 16Mbits/sec over wireless, methinks you're going to have to do some careful benchmarking and shopping. Many routers will not pass 16Mbits/sec. See chart at:
These are for wired, not wireless connections. Wireless only makes it worse. With 802.11g only, running at the maximum of 54Mbits/sec data rate, the best you can do is about 25Mbits/sec thruput. That's under ideal conditions, which only exist in the advertisers imagination. Add a little interference, a few reflections, some multipath, a dash of frequency selective fading, and your theoretical thruput become much worse. If you're going to do benchmarking, see iPerf and Jperf.
For a major speed increase, think about trying MIMO. Here's where the specs really get ugly (and everyone lies). In theory, you can do up to about 400Mbits/sec throughput, but nobody has been able to demonstrate that. Here's 300Mbits/sec:
I've seen 225Mbits/sec, but only in a rather unrealistic laboratory arrangement. That was at a range of about 8 meters. If you try going through a wall or two, your speed will drop back to 802.11g speeds and below. More realistically, you might get about 50Mbits/sec thruput, which should be sufficient for your 16Mbits/sec connection.
Incidentally, the 40MHz bandwidth flavor of MIMO (802.11n) disables
802.11b legacy compatibility, so you won't have to worry about that slow down. You can also disable 802.11g compatibility, but that results in some rather bizarre range versus speed effects.Also, DOCSIS 3.0 is probably coming. Comcast and others are claiming speeds up to 50Mbits/sec sec. You'll need a new cable modem (Motorola SB6120 and SBV6220), and some care in selecting your router for thruput performance.
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