Command Reference Guide

3Com Router 3000 Ethernet Family
Command Reference Guide Chapter 2 ARP Configuration Commands
3Com Corporation
2-10
The aging of an authorized ARP entry is implemented by the mechanism of ARP ping.
The default aging time of an authorized ARP entry is the time that three ARP ping
operations takes when no responses are received. Since the ARP ping interval is 30
seconds, the default aging time of an authorized ARP entry is 90 seconds. If no
response is received for an authorized ARP entry or if the DHCP server fails to update
the entry by re-adding the entry for example, after 90 seconds elapse, the entry ages
out. The DHCP server is then notified of this.
Example
# Configure an aging time of 120 seconds for the authorized ARP entries on interface
Ethernet1/0/0.
[3Com-Ethernet1/0/0] arp security time-out 120
2.4.3 dhcp server synchronize arp (in Interface View)
Syntax
dhcp server synchronize arp
undo dhcp server synchronize arp
View
Interface view
Parameter
None
Description
Use the dhcp server synchronize arp command to enable authorized ARP for a
DHCP interface address pool.
Use the undo dhcp server synchronize arp command to disable authorized ARP for
a DHCP interface address pool.
By default, authorized ARP is disabled.
After you enable authorized ARP for a DHCP interface address pool, the sytem permits
IP addresses allocated from the interface address pool to be resolved dynamically
using ARP, and allows the corresponding authorized ARP entries to be added to the
ARP table.
Related command: dhcp select interface, dhcp server synchronize arp interface,
and synchronize arp.
Example
# Enable authorized ARP in interface view.
[3Com] interface ethernet 1/0/0