AP541N wireless clients sporadically not acquiring dhcps

[cascoli_2008]

I was having this issue with my Dell Precision M70 laptop until I made this tweak to the Intel Pro Wireless 2200BG card that is built-in and so far its seems to be making a difference with it connecting to our Cisco 541L APs and acquiring a DHCP from our network.  However, the only thing different I noticed after making this change is that it is initially a bit slow at connecting to the Cisco APs.

http://www.intel.com/support/wireless/wlan/sb/cs-006205.htmUse Intel® PROSet/Wireless WiFi Connection Utility to Set CAM1.     Click Advanced > Adapter Settings > Advanced tab. 2.     Select Power Management and uncheck Default / Auto and move the slider to Highest / Maximum Performance.If the slider is already at Highest / Maximum Performance, move the slider to another setting and then back to Highest / Maximum Performance.

We are still experiencing this issue with our Dell Latitude E4200 laptops but need to verify that they are using the latest wireless network adapter drivers.  In addition, I am planning to tweak the PSP as I did with the Intel Pro Wireless 2200 BG.

F.Y.I. Our PDC and Primary DNS server is a Windows Server 2000

         Our BDC, Secondary DNS and DHCP server is a Windows Server 2003

Any help or suggestions would be greatly appreciated!

Sincerely,

Carmine

[cascoli_2008]

Steve,

I did before following Vicent's instructions.

The Cisco AP541 access point answers to DHCP Discover by an IP *unicast* DHCP Offer while the W2K3 DCHP server answers to DHCP Discover by an IP *broadcast* DHCP Offer !

Reading the following page, you can see this is an MS DHCP feature that causes some known issues with some 3rd party network equipments.
http://blogs.technet.com/teamdhcp/archive/2009/02/12/dhcp-broadcast-flag-handling-in-windows-7.aspx

To avoid this and make the MS DHCP server answer by unicast DHCP Offers, you should create the following DWORD entry into your W2K3 server's hive :
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DHCPServer\Parameters\*IgnoreBroadcastFlag*
and set it's value to *0* as explained here : http://technet.microsoft.com/en-us/library/cc958946.aspx

This solved the problem for me : restarting the DHCPServer service after creating this entry, without rebooting the AP nor putting off/on it's radio interface, causes the clients to aquire immediatly an IP address from the W2K3 DHCP server.

Regards
Carmine

[Steven DiStefano]

Hi Carmine,

First, thank you for all you help BTW.   We appreciate it.

... perhaps another way to skin this cat if it happens again...

(some Engineers suggested this to see if it helped and it would tell more about the problem...)

On AP541N GUI on the Wireless Advanced tab.

Disable Broadcast/Multicast Rate Limiting

[UMS-Orsay]

Hi Steve

Disabling Broadcast/Multicast Rate Limiting is the default config, and for my part I let this setting as is since the begining (except for a 2 days long test that didn't improved anything).

I'm ok to say that changing the MS DHCP response rules does not resolve the whole issue : It only allows standard DHCP clients (mainly Dell laptops for my part) to connect and communicate trough the AP even when it starts working "degraded mode"... but I still encouter some problem with more "light" clients as Aginova thremo/hygro probes.

Concerning the SBSC, I'm affraid I've no specific contract with Cisco except the fact I bought 2 APs... but It's older thant 90 days...

Would it be usefull to send the equipment's serial number to someone ?

Regards

Vincent

[Steven DiStefano]

If you didnt purchase the 3 year SKU for the product, I am not sure you can buy it on the fly, but you should check with your Small Business Account manager.

[Steven DiStefano]

Sounds like you may be using older firmware, since v1.8.0 has bcast/mcast rate limited ENABLED by default.

Per the help file in v.1.8.0, if you have this firmware version and your multicast is disabled by default you must do a factory default and reconfigure (the config file can get misinterpreted as many default parameters were changed between the two available f/w versions).

Steve

[amcsolutions]

Anybody get anywhere with this?

Although I don't like the idea of a registry fix being required to get an access point to work, I'd gladly oblige and test it out.

Unfortunately, I'm getting DHCP from a Sonicwall firewall.

I've disabled the broadcasting stuff recommended but still have to reboot the access point every couple hours to keep a connection.

Anybody else find a solution, besides returning these devices for other products?

[cascoli_2008]

One thing I have noticed with Dell laptops using the Dell or Intel wireless utility to manage wireless networks.  If you are trying to use the built-in Microsoft Windows wireless utility to manage your wireless network and you have either the Dell or Intel wireless utility enabled then this can confuse the wireless adapter and prevent it from acquiring a dhcp address.  The best solution is to uninstall it or disable it in services.

Best Regards,

Carmine

[Steven DiStefano]

Tier 2 Support and the BU have communicated to us  that the Level 1 SBSC agents were informed of this AP541N issue and another "Degrading" issue as being solved in  the next FW release for this product.  When customers call SBSC, the support the agents will follow proper protocol and due  diligence to determine the problem, and in the event it is considered to  be resolved in the coming release, the case will be escalated to 2^nd level support.  At that time and at the Partners discretion, access to  the beta firmware 1.9.0 in test right now can be given, once a beta agreement has been accepted.

Any Partner experiencing either DHCP issues or degrading service, please contact the SBSC for further  resolution.

I do  not have an ETA for the formal release of 1.9.0.

Steve DiStefano

Systems  Engineer,

Partner Sales, U.S.

[cascoli_2008]

Hi Steve:

Thanks for the update.  Can you let me know when the version 1.9 firmware gets released.

Have a great day!

Carmine

[Steven DiStefano]

We will come back and post when the FW is officially released.

[cascoli_2008]

Thanks man.

[Steven DiStefano]

The latest firmware for the Cisco Small Business Pro Wireless Access Point (AP541N) is now online.  The firmware new firmware version is 1.9.0.

Here is the link to the release notes: http://www.cisco.com/en/US/docs/wireless/access_point/csbap/AP541N/release_notes/78-19182.pdf

[cascoli_2008]

Thanks Steven.

Best Regards,

Carmine

[cascoli_2008]

Hi Steve:

I hope things are going well.  Do you know if Cisco has release any new firmware upgrades since version 1.9.

Thanks,

Carmine

[Christopher Adlam]

The most recent release is now 1.9.1 for the AP541N. It was released on the 3rd of June.

Release notes through to this release:

http://www.cisco.com/en/US/docs/wireless/access_point/csbap/AP541N/release_notes/78-19182.pdf

The issues listed in this thread should have been fixed in the 1.9.0 release, as per the following two closed caveats in the release notes:

Closed Caveats
The following caveats have been resolved in version 1.9.0:

CSCtg28316—WL Driver Multicast Queue Freezes
After a period of time, the access point stops forwarding Multicast or Broadcast
frames. Also, the last frame on the MCast queue is not always cleared.

CSCtg28338—WPA Key Refresh Freezes
If during disassociation the access point is refreshing a client broadcast key, that
client is not accounted for and the WPA key state machine freezes.

Though the new open caveats for 1.9.1 do prompt some worry:

Open Caveats

CSCtg14132—Station Isolation is Sporadic
Occasionally when Station Isolation (local LAN communication) is set to Disabled
auto, the device reverts to a Blocking state. The configuration continues to
indicate that the feature is Disabled. As a result, computers cannot access local
devices, such as printers. Access to remote devices (outside the local AP LAN)
can be accessed (for example, access to an external Web site).
Workaround: Reboot or restart the device.

CSCtg12675—MAC Filtering Set To Block Fails to Block Access
If you set MAC Filtering to block specified addresses, the device fails to prevent
association and authentication.
Workaround: None