by Tdarcos » Fri Mar 20, 2015 6:06 pm
I'm not sure how much of this you are aware of so forgive me if I go over stuff you already know.
When a device first needs to obtain an IP address it broadcasts a DHCP request to any srver, and some DHCP server that sees it assigns the device the IP address to the device's MAC address, along with other information such as the network mask and the gateway address, and, most importantly, a time limit it is promised to be granted the assignment for, which is called a "lease." Unless you set it differently the lease is usually one week.
The device will, when 1/2 of the lease time has expired, issue a request to renew its lease. If it does not get a response it will try again at 1/2 the remaining time, and keep repeating a request for a new lease at each 1/2 of the remaining lease time until it gets one or the lease expires. So, on a one week lease, it will try to renew at 3 1/2 days, then if that fails at about 30 hours, then 15 hours, and so on.
Now, if you put the mac address of a device along with the IP address in the router's permanent assignment table, the router's DHCP server simply never changes the IP address and gives that MAC address the same IP address every time it requests an assignment even if there were lower numbers available. It also never gives any other MAC address that IP.
So the point being is that a DHCP server such as your typical router / wireless router should accept DHCP lease requests all the time and it shouldn't matter whether a device already has an IP address, the device is going to ask to renew its lease from time to time. And it's possible if the device has cleared itself (like IPCONFIG /RELEASE forllowed by IPCONFIG /RENEW) that it can request a lease even if it still has time remaining on an existing lease.
As for router response problems, I have found lately that it makes sense to reboot the router on a regular basis - every few days - because sometimes the networking stops working and servers on my network suddenly vanish even when they were working a couple minutes earlier.
I'm not sure how much of this you are aware of so forgive me if I go over stuff you already know.
When a device first needs to obtain an IP address it broadcasts a DHCP request to any srver, and some DHCP server that sees it assigns the device the IP address to the device's MAC address, along with other information such as the network mask and the gateway address, and, most importantly, a time limit it is promised to be granted the assignment for, which is called a "lease." Unless you set it differently the lease is usually one week.
The device will, when 1/2 of the lease time has expired, issue a request to renew its lease. If it does not get a response it will try again at 1/2 the remaining time, and keep repeating a request for a new lease at each 1/2 of the remaining lease time until it gets one or the lease expires. So, on a one week lease, it will try to renew at 3 1/2 days, then if that fails at about 30 hours, then 15 hours, and so on.
Now, if you put the mac address of a device along with the IP address in the router's permanent assignment table, the router's DHCP server simply never changes the IP address and gives that MAC address the same IP address every time it requests an assignment even if there were lower numbers available. It also never gives any other MAC address that IP.
So the point being is that a DHCP server such as your typical router / wireless router should accept DHCP lease requests all the time and it shouldn't matter whether a device already has an IP address, the device is going to ask to renew its lease from time to time. And it's possible if the device has cleared itself (like IPCONFIG /RELEASE forllowed by IPCONFIG /RENEW) that it can request a lease even if it still has time remaining on an existing lease.
As for router response problems, I have found lately that it makes sense to reboot the router on a regular basis - every few days - because sometimes the networking stops working and servers on my network suddenly vanish even when they were working a couple minutes earlier.