Avaya Configuring BOOTP Services Instrukcja Użytkownika Pobierz pdf (Strona 54)

Configuring SNMP, BootP, and DHCP Services

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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.

• If the target server cannot supply the requested configuration parameters, it

sends a DHCPNAK packet to the client through the BootP relay agent.

When the client receives the DHCPNAK packet, it broadcasts a new

DHCPDISCOVER packet and the process begins again.

A client may choose to relinquish its IP address before the lease period expires by

sending a DHCPRELEASE packet to the server. This packet contains the

relinquished IP address in the client IP address field and the client’s MAC address

in the client hardware address field.

Reacquiring the Same IP Address

A client may want to reuse an IP address that a server allocated earlier using a

BootP relay agent. In this case, the interchange between client and server omits

some of the steps described in the previous sections.

The client can acquire the same IP address again using a BootP relay agent by

following these steps:

The client starts the interchange by broadcasting a DHCPREQUEST packet

that contains its previous IP address in the client IP address field.

The BootP relay agent receives the packet and forwards it to DHCP servers on

other networks.

DHCP servers examine the client’s configuration parameters in the options

field of the DHCPREQUEST packet.

The server that originally supplied the configuration parameters recognizes

them and responds with a DHCPACK packet.

When a client receives a DHCPACK packet, it accepts or declines the

parameters, as it would when receiving a new IP address.

If a client’s request is invalid (for example, if the client has moved to a new

network), servers respond with a DHCPNAK packet. If a client receives only

DHCPNAK packets, it must request a new IP address by broadcasting a

DHCPDISCOVER packet.

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Avaya Configuring BOOTP Services Instrukcja Użytkownika Strona 54