Avaya Configuring BOOTP Services Manual de usuario descargar pdf (Pagina 52)

Configuring SNMP, BootP, and DHCP Services

2-20

308644-15.1 Rev 00

The packet relay process uses these fields as follows:

The BootP relay agent receives the packet and, if it accepts the packet,

transmits it to DHCP servers on other networks.

DHCP servers on the local segment see the broadcast packet and respond with

a DHCPOFFER packet that includes an available IP address and other

configuration information. Before offering the IP address, the DHCP servers

may generate an ARP or ICMP echo request on the network to determine

whether the IP address is already in use by another device.

When a DHCP server offers an IP address, that address is temporarily

unavailable to other clients. If the client does not accept or reject the address

within a certain period of time, the server reclaims it. The address is then

available for other clients.

The BootP relay agent receives the DHCPOFFER packet and examines the

packet. If the BootP relay agent accepts the packet, it forwards it to the client.

If a client does not receive a DHCPOFFER packet within a specified amount

of time after broadcasting a DHCPDISCOVER packet, it sends the packet

again. The client may rebroadcast the packet a number of times. However,

clients operating on systems running Windows

95 broadcast four

DHCPDISCOVER packets, each 2 seconds apart.

The client may receive DHCPOFFER packets from several potential servers.

If you configure the client to wait for multiple responses, it compares

configuration parameters in the DHCPOFFER packets to decide which server

to target.

Client hardware address 16 The hardware address of the client

Server name 64 Optional DHCP server host name, represented as

a null terminated string

File name 128 A boot file name. Represented as a null terminated

string in a DHCPDISCOVER message, and a fully

qualified directory path name in a DHCPOFFER

message.

Options 312 Variable length optional parameters field

Table 2-4. Fields in a DHCP Packet

(continued)

Field Octets Description

1 2 ... 47 48 49 50 51 52 53 54 55 56 57 ... 195 196

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Avaya Configuring BOOTP Services Manual de usuario Pagina 52