HP VPN Firewall Appliances Network Management Configuration Guide

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Configuring the maximum number of dynamic ARP entries for
an interface
An interface can dynamically learn ARP entries, so it might hold too many ARP entries. To solve this
problem, you can set the maximum number of dynamic ARP entries that an interface can learn. When the
maximum number is reached, the interface stops learning ARP entries.
A Layer 2 interface can learn an ARP entry only when both its maximum number and the VLAN
interface's maximum number are not reached.
To set the maximum number of dynamic ARP entries that an interface can learn:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Set the maximum
number of dynamic
ARP entries that the
interface can learn.
arp max-learning-num
number
Optional.
By default, a Layer 2 interface does not limit the number
of dynamic ARP entries. For the maximum number of
dynamic ARP entries that a Layer 3 interface can learn,
see Network Management Command Reference.
If the value of the number argument is set to 0, the
interface is disabled from learning dynamic ARP entries.
Setting the aging timer for dynamic ARP entries
Each dynamic ARP entry in the ARP table has a limited lifetime, called aging timer. The aging timer of a
dynamic ARP entry is reset each time the dynamic ARP entry is updated. Dynamic ARP entries that are not
updated before their aging timers expire are deleted from the ARP table.
To set the aging timer for dynamic ARP entries:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Set the aging timer for
dynamic ARP entries.
arp timer aging aging-time
Optional.
20 minutes by default.
Enabling natural mask support for ARP requests
This feature enables the device to learn the sender IP and MAC addresses in a received ARP request
whose sender IP address is on the same classful network as but a different subnet from the IP address of
the receiving interface. A classful network refers to a class A, B, or C network.
For example, VLAN-interface 10 with IP address 10.10.10.5/24 receives an ARP request from
10.11.11.1/8. Because the subnet address calculated by the AND operation of 10.11.11.1 a n d t h e 24 - b i t
subnet mask of the receiving interface is not in the subnet 10.10.10.5/24, VLAN-interface 10 cannot
process the ARP packet.