3com WX3000 Manuel D’Utilisation

 

1-3 

5 Chaos 

6 IEEE802.X 

7 ARC 

network 

 

In an Ethernet, the MAC addresses of two hosts must be available for the two hosts to communicate 

with each other. Each host in an Ethernet maintains an ARP table, where the latest used IP 

address-to-MAC address mapping entries are stored. The device provides the display arp command to 

display the information about ARP mapping entries. 

ARP entries in a device can either be static entries or dynamic entries, as described in 

Table 1-3 ARP entries  

Static ARP entry 

Manually configured 

Manual maintenance 

Dynamic ARP entry 

Dynamically generated 

ARP entries of this type age with time. The aging 
period is set by the ARP aging timer. 

 

Figure 1-2 ARP process 

Sender MAC 

address

00a0-2470 -febd

Target  IP 

address

192.168.1.1

Target IP 

address

192.168 .1. 2

Host A

192. 168.1.1

0002-6779-0f4c

Host B

192. 168.1.2

00a0-2470 -febd

Target MAC 

address

0000 -0000-0000

Sender IP 

address

192 .168.1.1

Sender IP 

address

192.168.1. 2

Sender  MAC 

address

Target MAC 

address

0002-6779-0f4c

0002 -6779 -0f4c

 

 

Suppose that Host A and Host B are on the same subnet and that Host A sends a message to Host B. 

The resolution process is as follows: 

2)  Host A looks in its ARP mapping table to see whether there is an ARP entry for Host B. If Host A 

finds it, Host A uses the MAC address in the entry to encapsulate the IP packet into a data link layer 

frame and sends the frame to Host B. 

3)  If Host A finds no entry for Host B, Host A buffers the packet and broadcasts an ARP request, in 

which the source IP address and source MAC address are respectively the IP address and MAC 

address of Host A and the destination IP address and MAC address are respectively the IP 

address of Host B and an all-zero MAC address. Because the ARP request is sent in broadcast