Please Whitelist This Site?
I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)
If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.
If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.
Thanks for your understanding!
Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide
NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.
DHCP Lease "Life Cycle" Overview (Allocation, Reallocation, Renewal, Rebinding and Release) and Lease Timers
(Page 2 of 2)
Renewal and Rebinding Timers
The processes of renewal and rebinding
are designed to ensure that a client's lease can be extended before
it is scheduled to end, so no loss of functionality or interruption
occurs to the user of the client machine. Each time an address is allocated
or reallocated, the client starts two timers that control the renewal
and rebinding process:
- Renewal Timer (T1): This timer is set
by default to 50% of the lease period. When it expires, the client will
begin the process of renewing the lease. It is simply called T1
in the DHCP standards.
- Rebinding Timer (T2): This timer is set
by default to 87.5% of the length of the lease. When it expires, the
client will try to rebind, as described above. It is given the snappy
name T2 in the DHCP standards.
Naturally, if the client successfully
renews the lease when the T1 timer expires, this will result
in a fresh lease, and both timers will be reset. T2
only comes into play if the renewal is not successful. It is possible
to change the amount of time to which these timers are set, but obviously
T1 must expire before T2, which must in turn expire before
the lease itself ends. These usually are not changed from the default,
but may be modified in certain circumstances.
Key Concept: DHCP leases follow a conceptual life cycle. The lease is first assigned to the client through a process of allocation; if the device later reboots it will reallocate the lease. After a period of time controlled by the renewal timer (T1), the device will attempt to renew its lease with the server that allocated it. If this fails, the rebinding timer (T2) will go off and the device will attempt to rebind the lease with any available server. The client may also release its IP address if it no longer needs it.
The lease life cycle is described
in the DHCP standards in the form of states that the client moves through
as it acquires a lease, uses it, and then either renews or ends it.
The next section
on DHCP configuration describes these
states and the specific exchanges of messages between a client and server
to accomplish different lease activities.
|If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Table Of Contents - Contact Us
The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005
© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.