3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring Gratuitous ARP 197
Suppose that the IP address of Vlan-interface10 is 10.10.10.5/24 and that this
interface receives an ARP packet from 10.11.11.1. Because these two IP addresses
are not on the same subnet, Vlan-interface10 cannot process the packet. With this
feature enabled, the device will make judgment on natural network basis. Because
the IP address of Vlan-interface10 is a Class A address and its default mask length
is 8, these two IP addresses are on the same natural network. In this way,
Vlan-interface10 can learn the MAC address of the source IP address 10.11.11.1.
Follow these steps to enable the support for ARP requests from a natural network:
ARP Configuration
Examples
Network requirement
■ Disable ARP entry check.
■ Set the aging time for dynamic ARP entries to 10 minutes.
■ Enable the support for ARP requests from a natural network.
■ Set the maximum number of dynamic ARP entries that VLAN-interface 10 can
learn to 1,000.
■ Add a static ARP entry, with the IP address being 192.168.1.1, the MAC
address being 00e0-fc01-0000, and the outbound interface being
Ethernet1/1/1 of VLAN 10.
Configuration procedure
<Sysname> system-view
[Sysname] undo arp check enable
[Sysname] arp timer aging 10
[Sysname] naturemask-arp enable
[Sysname] vlan 10
[Sysname-vlan10] quit
[Sysname] interface ethernet 1/1/1
[Sysname-Ethernet1/1/1] port access vlan 10
[Sysname-Ethernet1/1/1] quit
[Sysname] interface Vlan-interface 10
[Sysname-Vlan-interface10] arp max-learning-num 1000
[Sysname-Vlan-interface10] quit
[Sysname] arp static 192.168.1.1 00e0-fc01-0000 10 ethernet1/1/1
Configuring
Gratuitous ARP
Introduction to
Gratuitous ARP
A gratuitous ARP packet is a special ARP packet, in which the source IP address
and destination IP address are both the IP address of the sender, the source MAC
address is the MAC address of the sender, and the destination MAC address is a
broadcast address.
To do... Use the command... Remarks
Enter system view system-view -
Enable the support for ARP
requests from a natural
network
naturemask-arp enable Required
Disabled by default