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802.11b/g mixed mode, WLAN SSID using b/g, WLAN SSID using g only

If I configure a WLAN to use 802.11b/g and another WLAN to use 802.11g only in an LWAPP environment (i.e. 4400 Series Controller with Cisco 1242 LWAPP Access Points), will the clients who connect to the WLAN that uses 802.11g only drop their data rate and overall throughput?

7 REPLIES
Hall of Fame Super Silver

Re: 802.11b/g mixed mode, WLAN SSID using b/g, WLAN SSID using g

The answer is yes.... due to the fact it is the same radio. What you mentioned is a policy that allows the device to only connect to the allowed radio type.

-Scott
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New Member

Re: 802.11b/g mixed mode, WLAN SSID using b/g, WLAN SSID using g

Is there a way to configure a policy for each radio, i.e. one radio with a WLAN using 802.11b/g and a second radio with a WLAN using 802.11g only? Is there also a way to configure each WLAN group of APs to use a specific channel so they don't interfere with each other, i.e. WLAN 802.11b/g using channel '1' and WLAN 802.11g using channel '11'? If this is possible, would that solve the problem?

Hall of Fame Super Silver

Re: 802.11b/g mixed mode, WLAN SSID using b/g, WLAN SSID using g

You can have two ap's one that only has b enabled and the other that has g enabled. You can't have an ap do both since it is one 2.4ghz radio per ap and one 5ghz radio if you have that.

You can also define or hard set the channel, so you can have three ap's, using channel 1, 6, or 11.

-Scott
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Hall of Fame Super Silver

Re: 802.11b/g mixed mode, WLAN SSID using b/g, WLAN SSID using g

Another thing, do you want to do this because you are noticing a performance hit? Depending on how many users, you might not even notice a difference.

-Scott
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New Member

Re: 802.11b/g mixed mode, WLAN SSID using b/g, WLAN SSID using g

Well one WLAN is being used for voice, wireless IP Phones. For now we'll call it WLAN_Voice. The other WLAN is being used for data, i.e. clients on laptops, for now we'll call it WLAN_Data. The wireless IP Phones can only use the 802.11b and we want the clients on laptops to be able to use the 802.11g because of the higher throughput. We tried the 802.11a, but the coverage was very spotty. This is what I was thinking:

WLAN_Voice

1 Controller

x amount of Cisco 1242 APs

Radio Policy 802.11b/g

Fixed Channel 1

WLAN_Data

1 Controller

x amount of Cisco 1242APs

Radio Policy 802.11g

Fixed Channel 11

Would this solution work?

Hall of Fame Super Silver

Re: 802.11b/g mixed mode, WLAN SSID using b/g, WLAN SSID using g

In a situtaion where you have to use the same channel for a given ssid throughout, you can. Usually in a distributed antenna system. Is this the prefered way, no its not. Back to the basic rule... If ap1 and ap2 is on the same channel, you need to have 19db seperation. So at the edge of ap1 cell of -67, you need to see ap2 at -87 or worse. This is best case senerio.... There will be times where you might not have that 19db seperation. I have seen many installs that use B phones and have B and G users with no problems at all. QoS is what you need.

-Scott
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Hall of Fame Super Silver

Re: 802.11b/g mixed mode, WLAN SSID using b/g, WLAN SSID using g

Take a look at this document, it show what I was trying to explain. This is for voice deployment.

http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7920/5_0/english/design/guide/wrlradio.html#wp1043132

-Scott
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