IP address change

[Guest]

Earlier this evening whilst on the net, I lost connection. This was noticed
when my LAN notified me it had reconnected. I could not get back on the
internet. Investigation (ipconfig) found that my IP address had
dramticatically changed from 192.x.x.x to 169.254.155.65, with no default
gateway setting. Obtaing IP address automatically no longer working (??).
I've had to set up manually to reconnect. Can anyone tell me what's happened
???? and why ???

I'm using firewall (SP2 and Panda) and AV. Everything is upto date.

 

[Guest]

The 169.X.X.X address you received is an APIPA address. This means that when
your computer reconnected it was not able to receive an IP address from the
DHCP Server. Possbile cause could be that there were no available IP address
leases left in the DHCP Servers IP address pool. Check with your admin to
see if he needs to add more IP addressed to the pool. Usually when you
receive an APIPA address, there is a connection problem or a DHCP Server
problem.

 

[Guest]

Thanks for quick reply. I'm no expert so please bear with me.

This is a home wired network. The (gateway) PC connected to the internet
(cable Broadband) is in the dining room. There are three further (client)
PC's upstairs in bedrooms.

This network has been running for a min 2 years. Until today, I've had all
three (plus laptop) connected to internet, all auto (DHCP) configured

So, if I understand correctly, two of the three were able to find DHCP
server to obtain an IP address. The third could not, so it used APIPA to
auto configure itself (though still without success)

Because it still couldn't connect to internet, I presume this was because
the default gateway address wasn't found/set (as shown by ipconfig). Manual
config therefore being only option.

I still don't undertand why no longer working when it has been for some
considerable time. At this moment the other two PC's are DHCP
configured/connected to internet, this one manually configured/connected, so
doesn't appear to be connection or DHCP problem (??). Is it possible that I
have file corruption somewhere on this PC??

 

[Steve Winograd [MVP]]

Earlier this evening whilst on the net, I lost connection. This was noticed
when my LAN notified me it had reconnected. I could not get back on the
internet. Investigation (ipconfig) found that my IP address had
dramticatically changed from 192.x.x.x to 169.254.155.65, with no default
gateway setting. Obtaing IP address automatically no longer working (??).
I've had to set up manually to reconnect. Can anyone tell me what's happened
???? and why ???

I'm using firewall (SP2 and Panda) and AV. Everything is upto date.

Microsoft specifically says not to use SP2's firewall in conjunction
with another firewall, because it can cause network problems. Run
either the Windows Firewall or Panda's firewall, but not both.
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

Please post any reply as a follow-up message in the news group
for everyone to see. I'm sorry, but I don't answer questions
addressed directly to me in E-mail or news groups.

Microsoft Most Valuable Professional Program
http://mvp.support.microsoft.com

 

[Bob Willard]

Thanks for quick reply. I'm no expert so please bear with me.

This is a home wired network. The (gateway) PC connected to the internet
(cable Broadband) is in the dining room. There are three further (client)
PC's upstairs in bedrooms.

This network has been running for a min 2 years. Until today, I've had all
three (plus laptop) connected to internet, all auto (DHCP) configured

So, if I understand correctly, two of the three were able to find DHCP
server to obtain an IP address. The third could not, so it used APIPA to
auto configure itself (though still without success)

Because it still couldn't connect to internet, I presume this was because
the default gateway address wasn't found/set (as shown by ipconfig). Manual
config therefore being only option.

I still don't undertand why no longer working when it has been for some
considerable time. At this moment the other two PC's are DHCP
configured/connected to internet, this one manually configured/connected, so
doesn't appear to be connection or DHCP problem (??). Is it possible that I
have file corruption somewhere on this PC??

:

I assume that when you say gateway you don't mean a Gateway-brand PC but do mean
a PC with two NICs, one tied to a cable modem and one tied to a hub/switch to
which the other PCs are tied, and that the gateway PC runs ICS and is the
DHCP server for your LAN.

With that assumption, there is nothing wrong with the gateway PC because it
is correctly handing out IPAs to other PCs on your LAN. On the sick PC, start
by turning off all firewalls and AV apps, then manually assign an unused IPA in
the 192.168.0.2-192.168.0.99 range, then Run CMD and type PING 192.168.0.1 in
the CMD window. If PING works, then DHCP should also work and I'd suspect a
firewall was misconfigured; if PING times out, then I'd suspect a hardware
failure (bad/loose cable, bad hub/switch port, bad NIC) or a corrupted network
stack.

 

[Guest]

Steve,

Noted. I've been running both since release of SP2. It's only been last
couple of days that problems have occured. Within last half hour, son
"complained" of loss of internet connection - saw network icon ballon is sys
tray tell him LAN reconnected but could not connect to net. Again APIPA
actioned. I've had to set up manually. Does APIPA assume all PC's directly
connected to network ??? it doesn't pick up gateway IP if client. (checked
via cmd/ipconfig)

Regards

 

[Guest]

Bob,

Your assumption is correct.

I've configured "sick" PC manually without turning off firewall or AV and on
"OK" got instant reconnection. No problems. My son's PC (see reply to Steve)
jsut done same. Reconfigured manually and all OK.

Don't know what's going/gone on!!. Should I go back and set for auto
detection ???

Regards

 

[Steve Winograd [MVP]]

Steve,

Noted. I've been running both since release of SP2. It's only been last
couple of days that problems have occured. Within last half hour, son
"complained" of loss of internet connection - saw network icon ballon is sys
tray tell him LAN reconnected but could not connect to net. Again APIPA
actioned. I've had to set up manually. Does APIPA assume all PC's directly
connected to network ??? it doesn't pick up gateway IP if client. (checked
via cmd/ipconfig)

Regards

APIPA only assigns an IP address (in the 169.254.x.x subnet). It
can't assign a default gateway.

Try explicitly setting speed and duplex settings for the NIC on your
son's computer, as shown here:

Windows XP Network Troubleshooting - Problems with Network Cards
http://www.practicallynetworked.com/sharing/troubleshoot/networkcard.htm
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

Please post any reply as a follow-up message in the news group
for everyone to see. I'm sorry, but I don't answer questions
addressed directly to me in E-mail or news groups.

Microsoft Most Valuable Professional Program
http://mvp.support.microsoft.com

 

[Guest]

Steve,

Thanks for the this info. Already actioned. I'll reset to obtain an IP
address automatically when his PC available (playing games at moment) and see
if it works as expected.

 

[Bob Willard]

Bob,

Your assumption is correct.

I've configured "sick" PC manually without turning off firewall or AV and on
"OK" got instant reconnection. No problems. My son's PC (see reply to Steve)
jsut done same. Reconfigured manually and all OK.

Don't know what's going/gone on!!. Should I go back and set for auto
detection ???

Regards



:

If your sick PC can PING the gateway PC, then try DHCP again.

It is possible that the gateway PC was temporarily too busy to respond to
DHCP requests quickly, causing the DHCP clients to switch to APIPAs. That
is one of the advantages of hardware routing over software (ICS) routing.