1.8.1 Establishing the Configuration Task
Before configuring ARP-Ping IP, familiarize yourself with the applicable environment,
complete the pre-configuration tasks, and obtain the data required for the configuration. This
will help you complete the configuration task quickly and accurately.
Applicable Environment
ARP-Ping IP checks whether an IP address on a LAN is in use by sending ARP packets.
Before configuring an IP address for a device, ensure that this IP address is not in use by sending
ARP packets. You can configure ARP-Ping IP on the device.
Pre-configuration Tasks
Before configuring ARP-Ping IP, complete the following task:
l Setting link layer protocol parameters for interfaces to ensure that the link layer protocol
status on the interfaces is Up
Data Preparation
To configure ARP-Ping IP, you need the following data.
No.
Data
1 IP address to be checked
1.8.2 Checking an IP Address by Using ARP-Ping IP
ARP-Ping IP checks whether an IP address on a LAN is in use by sending ARP Request packets.
Context
ARP-Ping IP checks whether an IP address on a LAN is in use by sending ARP packets. You
can also use the ping command to check whether an IP address is in use, but the result of this
method may be inaccurate. The ping command uses Layer 3 packets as ICMP Echo Request
packets. If the destination host or the routing device enabled with the firewall function is
configured not to respond to the ICMP Echo Request packets, the destination host or the routing
device does not send ICMP Reply packets. Consequently, the IP address is considered unused.
ARP packets, which are Layer 2 protocol packets, can pass through the firewall that is configured
not to reply to ICMP Echo Request packets; therefore, the result of ARP-Ping IP is accurate.
Procedure
Step 1 Run:
arp-ping ip ip-address [ interface interface-type interface-number [ vlan-id vlan-
id ] ]
The AR150/200 is configured to check whether the IP address is in use on a LAN.
----End
Huawei AR150&200 Series Enterprise Routers
Configuration Guide - IP Service 1 ARP Configuration
Issue 02 (2012-03-30) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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