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Old 06-03-2010, 06:07 AM   #1
japlytic
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Talking IP address conflicts after waking up from standby/hibernation

On rare occasions, I get an IP address conflict after waking up from standby or hibernation.
On our network with three computers (set to DHCP), we have a printer at 192.168.1.20 (static) and an ADSL/wireless router at 192.168.1.254 and the DHCP server starts from 192.168.1.1
It is highly unlikely that there is a conflict with the printer.

To say simply (taking note that both PCs are set to DHCP), PC "A" has an IP address of 192.168.1.2 and PC "B" is off. PC "A" hibernates and PC "B" is turned on and receives an IP address of 192.168.1.2.
When PC "B" still has this IP address, PC "A" resumes from hibernation and tries to use IP address 192.168.1.2 , resulting in an IP address conflict.

Why can't network clients configured for DHCP renew its IP address after standby or hibernation (even though some renew the IP address when there is a conflict)?
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Old 06-03-2010, 06:56 AM   #2
stj
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Default Re: IP address conflicts after waking up from standby/hibernation

use fixed i.p.'s

standby will lose the dhcp table,
suspend will make the other machine delete the dhcp entry after a timeout period.

or:
run a nameserver and assign a fixed i.p. to each domain-name.
then when you start the pc it will always be assigned the same i.p.
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Old 06-03-2010, 07:52 AM   #3
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Default Re: IP address conflicts after waking up from standby/hibernation

or check if your router can be set to always use the same adress for each device.
some can, some not.
my Thomson router does it via binding the IPs to the MACs (and can be set individually for each client).
it's a bit less trouble than the all-static way since you don't have to configure the DNS settings client-side.
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Old 06-03-2010, 10:34 AM   #4
seanc
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Default Re: IP address conflicts after waking up from standby/hibernation

Agreed, set your router to always give the same IP address to a particular device/MAC address.

If your router doesn't support that, turn it's DHCP server off, build a Smoothwall. Enjoy.
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Old 06-03-2010, 11:52 AM   #5
retiredcaps
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Default Re: IP address conflicts after waking up from standby/hibernation

On some home based routers, you can set the DHCP lease time to 1 hour through 1 week. If you set it for a "longer" period, this *should* force the router to keep the MAC to IP binding even if the end device is asleep or hibernating. It *should* also prevent the router from handing out that used IP address because the MAC to IP binding still exists.

Quote:
Originally Posted by japlytic
On rare occasions, I get an IP address conflict after waking up from standby or hibernation.
On our network with three computers (set to DHCP), we have a printer at 192.168.1.20 (static) and an ADSL/wireless router at 192.168.1.254 and the DHCP server starts from 192.168.1.1
It is highly unlikely that there is a conflict with the printer.

To say simply (taking note that both PCs are set to DHCP), PC "A" has an IP address of 192.168.1.2 and PC "B" is off. PC "A" hibernates and PC "B" is turned on and receives an IP address of 192.168.1.2.
When PC "B" still has this IP address, PC "A" resumes from hibernation and tries to use IP address 192.168.1.2 , resulting in an IP address conflict.

Why can't network clients configured for DHCP renew its IP address after standby or hibernation (even though some renew the IP address when there is a conflict)?
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Old 06-06-2010, 12:35 AM   #6
AudioCraZ
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Default Re: IP address conflicts after waking up from standby/hibernation

There is an easier way to fix this.

In most routers, you can set the IP address via MAC address of a computer. That way, on some rare chance that something else gets on your network, it won't get your ip address because the router (DHCP server) is assigning the IP's, and it knows not to give away the IP set for your computer.
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Old 06-06-2010, 01:49 PM   #7
NxB
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Default Re: IP address conflicts after waking up from standby/hibernation

Just extend lease time. That is the easiest way.
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Old 06-23-2010, 12:11 PM   #8
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Default Re: IP address conflicts after waking up from standby/hibernation

Quote:
Originally Posted by NxB
Just extend lease time. That is the easiest way.
aggreed.

static ips for the home computers with exception of wireless client is way to go. so much easier and after a while you begin to correspond computers to IP internally without netbios or dns so your not always second guessing or having to do that extra step.

i got a low memory and dont use page files so that extra step would irritate or possibly mess me up when im in the zone doing a project. LOL
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