Overview Of Arp; Features Of Arp Supported By The S9300&S9300E - Huawei S9300 Configuration Manual

S9300&S9300E Terabit Routing Switch
Configuration Guide - IP Service

2.1 Overview of ARP

An Ethernet device must support ARP. ARP implements dynamic mapping between Layer 3 IP
addresses and Layer 2 MAC addresses.
Each host or device on the Local Area Network (LAN) can be configured a 32-bit IP address to
communicate with others. The assigned IP address is independent of the hardware address.
On the Ethernet, a host or a device transmits and receives Ethernet frames according to a 48-bit
Medium Access Control (MAC) address. The MAC address is also called the physical address
or the hardware address, which is assigned to an Ethernet interface when equipment is produced.
Therefore, on an interconnected network, an address resolution mechanism is required to provide
the mapping between MAC addresses and IP addresses.
The Address Resolution Protocol (ARP) maps an IP address to the corresponding MAC address.
2.2 Features of ARP Supported by the S9300&S9300E
ARP can operate in either of two modes: static and dynamic. The extensions of ARP include
proxy ARP, gratuitous ARP, and ARP-Ping.
ARP is only used in the IPv4 environment and can only run on Ethernet links.
Introduction to ARP-Ping
ARP-Ping consists of ARP-Ping IP and ARP-Ping MAC. ARP-Ping is developed to maintain
the deployed Layer 2 features.
Introduction to ARP-Ping IP
ARP-Ping IP uses ARP packets to check whether an IP address is used by another device on the
LAN.
Before configuring an IP address for a device, you need to check that this IP address is not used
by another device on the network by sending the ARP packets. Then, you can take appropriate
actions.
You can also run the ping command to check whether the IP address is used by another device
on the network. If enabled with the firewall function that does not reply to Ping packets, the
destination host and device do not reply to Ping packets and think that the IP address is not in
use. ARP is a Layer 2 protocol. In most cases, ARP packets can pass through the firewall. In
this way, the preceding situation does not occur.
Principles of ARP-Ping IP
ARP-Ping IP sends ARP Request packets. The following describes how to implement ARP-Ping
IP:
1.
2.
Issue 01 (2012-03-15)
After setting the specified IP address through command lines, you can send ARP Request
packets and start the timeout timer.
After receiving an ARP Request packet, each device or host on the LAN replies with an
ARP Reply packet.
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