sangbmt Advanced Member
Number of posts : 151 Warnings : Reputation : 0 Points : 5325 Registration date : 2011-01-10
| Subject: How is Address Renewal Process done in DHCP Sun Jan 23, 2011 3:13 am | |
| Basically, DHCP acquires the address, a DHCP client moves to the BOUND state. Upon entering the BOUND state, the client sets three timers which basically controls the lease period. There are three states in the renewal process, namely Renewal, Rebinding and the Expiration. A DHCP Server can specify the explicit values for the timers when it allocates the address to the client. So, if the server doesn't specify the timer values, the client will use the defaults. The default value for the first timer is one half which is the exact half of 50% of the total lease time. For requesting the renewal, the client needs to send the DHCPREQUEST message to the server from which the lease was first obtained. Here the client moves to renew the state and awaits the response. The DHCPREQUEST contains the IP address of the client which is currently used by it and then it asks the server to extend the server to extend the lease on the address. In the initial negotiation stage, a client can request about the period of extension, but the server fully controls the renewal process, as a server can only respond to the client's renewal request in one or two ways. It can direct or even instruct the client to stop using the address or it can approve the continued use. If the request is accepted, then server sends back the DHCPACK which is an acknowledgement message which causes the client to return the BOUND state and also continues the usage of the address. The DHCPACK can also contain the new values for the client's timer, so if the server disapproves of the continued usage then server sends the DHCPNACK which is basically the negative acknowledgement which causes the client to stop using the address immediately and then it returns to the INITIALIZE stage. As soon as the DHCPREQUEST is sent, it gets extension of the lease and clients remains in the RENEW stage. If no response arrives at this stage then server which is granted the lease becomes either down or unreachable. stock statistical analysisvaginal dryness | |
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