User Manual
UMN:CLI
V8102
401
DHCP server validates an IP address.
To set a validation value of how many responses from an IP address for a requested ping
or ARP, use the following command.
Command
Mode
Description
ip dhcp
{
arp
|
ping
}
packet
<0-
20>
Global
Sets a validation value of how many responses.
0-20: response value (default: 2)
To set a validation value of timeout for the responses from an IP address for a requested
ping or ARP, use the following command.
Command
Mode
Description
ip dhcp
{
arp
|
ping
}
timeout
<100-5000>
Global
Sets a validation value of timeout for the responses in
the unit of millisecond.
100-5000: timeout value (default: 500)
9.6.1.13
Authorized ARP
The authorized ARP is to limit the lease of IP addresses to authorized users. This feature
enables a DHCP server to add ARP entries only for the IP addresses currently in lease
referring to a DHCP lease table, discarding ARP responses from unauthorized users (e.g.
an illegal use of a static IP address).
When this feature is running, dynamic ARP learning on an interface will be disabled, since
DHCP is the only authorized component currently allowed to add ARP entries.
The authorized ARP is enabled only in a DHCP server.
To limit the lease of IP addresses to authorized users, use the following command.
Command
Mode
Description
ip dhcp authorized-arp
start
<120-2147483637>
timeout
<120-
2147483637>
Global
Discards an ARP response from unauthorized user.
start: starting time (default: 3600 sec)
timeout: expire time
ip dhcp authorized-arp
<120-
2147483637>
Discards an ARP response from unauthorized user.
120-2147483637: expire time
no ip dhcp authorized-arp
Disables the authorized ARP function.
You can verify the valid and invalid list for the authorized ARP. The valid list includes the
IP addresses currently in lease, while the invalid list includes the IP addresses that send
ARP requests, but not in lease. Both lists include IP addresses of a DHCP pool, but the
authorized ARP only allows the ARP response of the IP addresses in the valid list.
To display entries of the valid and invalid lists, use the following command.
Command
Mode
Description
show ip dhcp authorized-arp
Enable
Shows entries of the valid list.
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