Avaya Configuring SNMP, BOOTP, DHCP, and RARP Services Manual do Utilizador descarregar pdf (Página 88)

Configuring SNMP, BOOTP, DHCP, and RARP Services

3-4

Figure 3-3 shows the second and third stages of the process.

Figure 3-3. Requesting and Receiving IP Information

5. When the client has chosen a target server, it broadcasts a DHCPREQUEST

packet. The DHCPREQUEST packet contains the address of the target server

in the server IP address ﬁeld.

6. The router receives the packet and forwards it to all servers.

7. Those servers examine the packet, and if their IP addresses differ from the

value in the server IP address ﬁeld, they reclaim the IP addresses they

supplied in the DHCPOFFER packets. These addresses are now available for

other clients.

8. The target server recognizes its IP address in the server IP address ﬁeld, and

responds to the DHCPREQUEST packet as follows:

• If the target server can supply the requested conﬁguration parameters, it

sends a DHCPACK packet to the client through the BOOTP relay agent.

The client examines the conﬁguration parameters in the DHCPACK

packet and records the duration of the lease period. If the client detects a

problem with the conﬁguration parameters, it sends a DHCPDECLINE

packet to the server and issues a new DHCPDISCOVER packet.

Otherwise, the client accepts the conﬁguration parameters.

3. Target server transmits

DHCPACK or DHCPNAK

packet to BOOTP relay

agent.

1. Client broadcasts

a DHCPREQUEST

packet.

4. BOOTP relay agent

transmits DHCPACK

or DHCPNAK

packet to client.

2. BOOTP relay agent

transmits DHCPREQUEST

packet to all servers

that supplied a

DHCPOFFER packet.

Router (BOOTP

Relay Agent)

Client

Server

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Avaya Configuring SNMP, BOOTP, DHCP, and RARP Services Manual do Utilizador Página 88