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Connection failure ip address invalid client move to

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Unformatted text preview: ead to a negative acknowledgment. If the client receipt this kind of message, he need to start again from the beginning (sending out a DHCPDISCOVER). 23 DHCP - Message Format OP HTYPE HLEN TRANSACTION ID SECONDS HOPS FLAGS FIELD CLIENT IP ADDRESS YOUR IP ADDRESS SERVER IP ADDRESS ROUTER IP ADDRESS CLIENT HARDWARE ADDRESS (64 Octets) SERVER HOST NAME (64 Octets) BOOTFILENAME (128 Octets) OPTIONS (312 Octets) DHCP MESSAGES ! (C) Herbert Haas 2005/03/11 24 This picture shows the DHCP message format. It is nearly completely the same like the BOOTP message format. The only different is the OPTION Field (DHCP MESSAGES) which contains the DHCPREQUEST, DHCPOFFER, DHCPDISCOVER, etc. 24 DHCP-specific Message Fields DHCPDICOVER Client broadcast to find DHCP server DHCPOFFER Response to a DHCPDISCOVER Offering an IP address DHCPREQUEST Request the parameters offered by one server DHCPINFORM Client ask for more information (C) Herbert Haas 2005/03/11 25 The DCHPINFORM message is used from the client, if this client needs more information then normal. 25 DHCP-specific Message Fields DHCPACK Acknowledgement from server to client DHCPNACK Negative ACK from server to client DHCPDECLINE Message from server to client indicating an error DHCPRELEASE Message from server to client canceling a lease and relinquishing network address (C) Herbert Haas 2005/03/11 26 26 Timer After DHCPACK beginning of the lease period is registered Located in the DHCPACK message Lease Time T1 (renewal attempt) T2 (sub renewal attempt) T1 and T2 are configured at the DHCP server T1 = 0,5 x lease time T2 = 0,875 x lease time (C) Herbert Haas 2005/03/11 27 DHCP relies on a leasing idea. The offered IP address expired after a special time. There are 3 times. There is a „lease time“, a T1 and a T2. T1 and T2 based on the lease timer (T1 ~ 0.5 x lease time; T2 ~ 0,875 x lease time). This multiplier is configured at the DHCP server. 27 Timer T1 and T2 start when client is bound Client RENEW the lease when T1 expired Client enters RENEWING state...
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