Avaya Configuring BOOTP Services Manual de usuario descargar pdf (Pagina 142)

Configuring SNMP, BootP, and DHCP Services

6-6

308644-15.1 Rev 00

Configuring the Number of Pings and the Ping Timeout

Before the DHCP server on the router assigns an IP address to a DHCP client, it

must ensure that the IP address is not already in use on the network. To verify that

the IP address is available, the DHCP server sends out an ICMP echo request,

called a ping.

• If the server fails to receive a response to the request within the specified

timeout period (ping request timeout), the DHCP server offers the IP address

and grants a lease to the client.

• If the DHCP server receives a response to the request, the IP address is

unavailable and therefore cannot be offered to the client.

By default, the DHCP server pings the IP address for a prospective DHCP client

only once before declaring it available.

By default, the DHCP server waits 750 milliseconds (that is, 0.75 second) for a

conflict detection ping to time out before determining that an IP address is

available to assign to a client. If you want to change the length of time that the

DHCP server waits, specify a value from 1 through 5000 milliseconds (5

seconds).

You can use the BCC or Site Manager to specify the number of times that the

DHCP server pings the IP address of a prospective DHCP client or to specify the

ping timeout value.

Using the BCC

To specify the number of ping attempts that the DHCP server makes to the IP

address of the prospective DHCP client, go to the global DHCP prompt (for

example,

box; ip; dhcp

) and enter:

ping-attempts

<value>

value

is any integer. The default value is 1.

Note:

Typically, DHCP clients retransmit a DHCPDISCOVER message after

2 seconds. Thus, if you specify a ping timeout value greater than 2000

milliseconds (2 seconds), the router may transmit spurious messages. The

same consideration applies if you set the values of the ping timeout and the

number of pings so that their product (timeout value times the number of

pings) is greater than 2000.

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Avaya Configuring BOOTP Services Manual de usuario Pagina 142