Switching AC to Battery loses wireless IP address

IBM Thinkpad T41 with embedded Cisco card. All the latest drivers, bios,
etc. IP address on wireless is lost when switching from battery to AC or AC
to battery. Scenario: wireless working great, excellent signal. Pull out
power cord. Within about a minute, connections fail, and IP address
169.254.200.115 is assigned to wireless connection. Signal is still strong,
but error message comes up saying "limited or no connectivity...". When I do
a repair, the connection comes right back with a valid address and wireless
works great again. Chatted with Microsoft XP2 support and IBM technical
support. Nobody has ever heard of this before. Well, now you have!

Other details:
Using windows to configure my wireless networking
WEP Open authentication
Connect when this network is in range "enabled".
Symptoms the same if firewall is on or off.

My thoughts - something in the power event within the OS (or IBM's power
management code) is killing the IP address - perhaps its going through a
"should I suspend" logic and that is where the problem is. When the new
power scheme is settled down (screen brightness lowered, etc), it does not do
a DHCP request to regain its lost IP address.

Looking forward to your comments and suggestions.

Hi,
I have seen a similar case in this NG not that long ago. My recommendation
was to check the power saving settings.
There was nothing wrong with the standard Windows power settings, but the
problem was solved by changing the power saving settings for the WLAN card
to Maximum.

br/rob

"skibum442" <(E-Mail Removed)> wrote in message
news:1AC47E95-5DD1-4AB6-ADBA-(E-Mail Removed)...
> IBM Thinkpad T41 with embedded Cisco card. All the latest drivers, bios,
> etc. IP address on wireless is lost when switching from battery to AC or
AC
> to battery. Scenario: wireless working great, excellent signal. Pull out
> power cord. Within about a minute, connections fail, and IP address
> 169.254.200.115 is assigned to wireless connection. Signal is still
strong,
> but error message comes up saying "limited or no connectivity...". When I
do
> a repair, the connection comes right back with a valid address and
wireless
> works great again. Chatted with Microsoft XP2 support and IBM technical
> support. Nobody has ever heard of this before. Well, now you have!
>
> Other details:
> Using windows to configure my wireless networking
> WEP Open authentication
> Connect when this network is in range "enabled".
> Symptoms the same if firewall is on or off.
>
> My thoughts - something in the power event within the OS (or IBM's power
> management code) is killing the IP address - perhaps its going through a
> "should I suspend" logic and that is where the problem is. When the new
> power scheme is settled down (screen brightness lowered, etc), it does not
do
> a DHCP request to regain its lost IP address.
>
> Looking forward to your comments and suggestions.
>
>

Thanks for the reply. On your advice, I tried setting the wireless card to
max power save (and the other two options as well), and saw no change to the
symptoms. Also tried disabling power management in the control panel's power
setting. When I switch AC to Battery, the screen flashes black for a
millisecond and ends up dimmer than under full power. I have not found any
control for that - to disable its routine - just in case that might fix it.

"Robban" wrote:

> Hi,
> I have seen a similar case in this NG not that long ago. My recommendation
> was to check the power saving settings.
> There was nothing wrong with the standard Windows power settings, but the
> problem was solved by changing the power saving settings for the WLAN card
> to Maximum.
>
> br/rob
>
> "skibum442" <(E-Mail Removed)> wrote in message
> news:1AC47E95-5DD1-4AB6-ADBA-(E-Mail Removed)...
> > IBM Thinkpad T41 with embedded Cisco card. All the latest drivers, bios,
> > etc. IP address on wireless is lost when switching from battery to AC or
> AC
> > to battery. Scenario: wireless working great, excellent signal. Pull out
> > power cord. Within about a minute, connections fail, and IP address
> > 169.254.200.115 is assigned to wireless connection. Signal is still
> strong,
> > but error message comes up saying "limited or no connectivity...". When I
> do
> > a repair, the connection comes right back with a valid address and
> wireless
> > works great again. Chatted with Microsoft XP2 support and IBM technical
> > support. Nobody has ever heard of this before. Well, now you have!
> >
> > Other details:
> > Using windows to configure my wireless networking
> > WEP Open authentication
> > Connect when this network is in range "enabled".
> > Symptoms the same if firewall is on or off.
> >
> > My thoughts - something in the power event within the OS (or IBM's power
> > management code) is killing the IP address - perhaps its going through a
> > "should I suspend" logic and that is where the problem is. When the new
> > power scheme is settled down (screen brightness lowered, etc), it does not
> do
> > a DHCP request to regain its lost IP address.
> >
> > Looking forward to your comments and suggestions.
> >
> >
>
>
>

Temporary fix: Turn off "Use windows to configure my wireless settings" in
the wireless card property sheet. Use Cisco configuration utility, ACU to
manually set up local networks. Downside is the loss of automatic functions.

The above configuration changes worked for me. I can come and go from
battery to AC power and my wireless network stays up. Microsoft support
suggested turning off the warning that the network had become unavailable.
That quieted down the message pop-ups, but did not solve the problem of a
lost network.

Since IBM has not heard of this, and neither have I, it might be safe to
assume that there is some hardware problem and the card is behaving
different in a low-power situation. The Repair functionality, as a last
resort, stops and re-starts the network card driver, so it basically resets
the hardware completely. I'm glad to hear that this at least fixes the
problem. However, this is not the behaviour we want from our wireless,
mobile laptops! I will ask a colleague if this problem has been reported
before with Wifi hardware, though I suspect not.

I would like to propose a test, but it would require using a different
network card. If you could borrow a PCMCIA card from a colleague and do the
same test it would be of great interest. Could this be done?

Brian

--
Brian Wehrle
(E-Mail Removed)
Software Test Engineer/Wireless Networking
Microsoft Corp.




"skibum442" <(E-Mail Removed)> wrote in message
news:A0BD6A1A-9002-4AD3-A675-(E-Mail Removed)...
> Thanks for the reply. On your advice, I tried setting the wireless card
> to
> max power save (and the other two options as well), and saw no change to
> the
> symptoms. Also tried disabling power management in the control panel's
> power
> setting. When I switch AC to Battery, the screen flashes black for a
> millisecond and ends up dimmer than under full power. I have not found
> any
> control for that - to disable its routine - just in case that might fix
> it.
>
> "Robban" wrote:
>
>> Hi,
>> I have seen a similar case in this NG not that long ago. My
>> recommendation
>> was to check the power saving settings.
>> There was nothing wrong with the standard Windows power settings, but the
>> problem was solved by changing the power saving settings for the WLAN
>> card
>> to Maximum.
>>
>> br/rob
>>
>> "skibum442" <(E-Mail Removed)> wrote in message
>> news:1AC47E95-5DD1-4AB6-ADBA-(E-Mail Removed)...
>> > IBM Thinkpad T41 with embedded Cisco card. All the latest drivers,
>> > bios,
>> > etc. IP address on wireless is lost when switching from battery to AC
>> > or
>> AC
>> > to battery. Scenario: wireless working great, excellent signal. Pull
>> > out
>> > power cord. Within about a minute, connections fail, and IP address
>> > 169.254.200.115 is assigned to wireless connection. Signal is still
>> strong,
>> > but error message comes up saying "limited or no connectivity...".
>> > When I
>> do
>> > a repair, the connection comes right back with a valid address and
>> wireless
>> > works great again. Chatted with Microsoft XP2 support and IBM
>> > technical
>> > support. Nobody has ever heard of this before. Well, now you have!
>> >
>> > Other details:
>> > Using windows to configure my wireless networking
>> > WEP Open authentication
>> > Connect when this network is in range "enabled".
>> > Symptoms the same if firewall is on or off.
>> >
>> > My thoughts - something in the power event within the OS (or IBM's
>> > power
>> > management code) is killing the IP address - perhaps its going through
>> > a
>> > "should I suspend" logic and that is where the problem is. When the
>> > new
>> > power scheme is settled down (screen brightness lowered, etc), it does
>> > not
>> do
>> > a DHCP request to regain its lost IP address.
>> >
>> > Looking forward to your comments and suggestions.
>> >
>> >
>>
>>
>>

I put a Cisco 340 wireless card into the PC Card slot, brought it up on my
WIFI/WEP network, and then switched from AC to battery and back. No network
problems like with the embedded card, which is a Cisco 350. So - is it
hardware or not? Because it fails when managed by Windows and works when
managed by the Cisco configuration utility - its hard to say. I'll try to
swap disks with a similar computer and see if the problem follows the disk.
Thanks for your ideas on this Brian. We now at least have another hint to
this obscure problem.

"Brian Wehrle [MSFT]" wrote:

> Since IBM has not heard of this, and neither have I, it might be safe to
> assume that there is some hardware problem and the card is behaving
> different in a low-power situation. The Repair functionality, as a last
> resort, stops and re-starts the network card driver, so it basically resets
> the hardware completely. I'm glad to hear that this at least fixes the
> problem. However, this is not the behaviour we want from our wireless,
> mobile laptops! I will ask a colleague if this problem has been reported
> before with Wifi hardware, though I suspect not.
>
> I would like to propose a test, but it would require using a different
> network card. If you could borrow a PCMCIA card from a colleague and do the
> same test it would be of great interest. Could this be done?
>
> Brian
>
> --
> Brian Wehrle
> (E-Mail Removed)
> Software Test Engineer/Wireless Networking
> Microsoft Corp.
>
>
>
>
> "skibum442" <(E-Mail Removed)> wrote in message
> news:A0BD6A1A-9002-4AD3-A675-(E-Mail Removed)...
> > Thanks for the reply. On your advice, I tried setting the wireless card
> > to
> > max power save (and the other two options as well), and saw no change to
> > the
> > symptoms. Also tried disabling power management in the control panel's
> > power
> > setting. When I switch AC to Battery, the screen flashes black for a
> > millisecond and ends up dimmer than under full power. I have not found
> > any
> > control for that - to disable its routine - just in case that might fix
> > it.
> >
> > "Robban" wrote:
> >
> >> Hi,
> >> I have seen a similar case in this NG not that long ago. My
> >> recommendation
> >> was to check the power saving settings.
> >> There was nothing wrong with the standard Windows power settings, but the
> >> problem was solved by changing the power saving settings for the WLAN
> >> card
> >> to Maximum.
> >>
> >> br/rob
> >>
> >> "skibum442" <(E-Mail Removed)> wrote in message
> >> news:1AC47E95-5DD1-4AB6-ADBA-(E-Mail Removed)...
> >> > IBM Thinkpad T41 with embedded Cisco card. All the latest drivers,
> >> > bios,
> >> > etc. IP address on wireless is lost when switching from battery to AC
> >> > or
> >> AC
> >> > to battery. Scenario: wireless working great, excellent signal. Pull
> >> > out
> >> > power cord. Within about a minute, connections fail, and IP address
> >> > 169.254.200.115 is assigned to wireless connection. Signal is still
> >> strong,
> >> > but error message comes up saying "limited or no connectivity...".
> >> > When I
> >> do
> >> > a repair, the connection comes right back with a valid address and
> >> wireless
> >> > works great again. Chatted with Microsoft XP2 support and IBM
> >> > technical
> >> > support. Nobody has ever heard of this before. Well, now you have!
> >> >
> >> > Other details:
> >> > Using windows to configure my wireless networking
> >> > WEP Open authentication
> >> > Connect when this network is in range "enabled".
> >> > Symptoms the same if firewall is on or off.
> >> >
> >> > My thoughts - something in the power event within the OS (or IBM's
> >> > power
> >> > management code) is killing the IP address - perhaps its going through
> >> > a
> >> > "should I suspend" logic and that is where the problem is. When the
> >> > new
> >> > power scheme is settled down (screen brightness lowered, etc), it does
> >> > not
> >> do
> >> > a DHCP request to regain its lost IP address.
> >> >
> >> > Looking forward to your comments and suggestions.
> >> >
> >> >
> >>
> >>
> >>
>
>
>

When WEP is disabled, symptoms disappear (ie, I can switch from AC to Battery
back and forth with no loss of IP address, no need to repair). When WEP
encryption is enabled, I always lose address when switching from AC to
Battery or back - and repair always fixes it. Result: SP2 reduces security
because workaround is to remove WEP from wireless.