3Com SuperStack 4 Configuration Manual page 75

IP Address Configuration
Example
Troubleshooting IP
Address Configuration
ARP Configuration
Introduction to ARP
Networking Requirements
Configure the IP address as 129.2.2.1 and subnet mask as 255.255.255.0 for
VLAN interface 1 of the Ethernet Switch.
Networking Diagram
Figure 20 IP Address Configuration Networking
Console cable
PC
Configuration Procedure
1 Enter VLAN interface 1.
[SW5500]interface vlan-interface 1
2 Configure the IP address for VLAN interface 1.
[SW5500-vlan-interface1]ip address 129.2.2.1 255.255.255.0
Fault 1: The Ethernet Switch cannot ping through a certain host in the LAN.
Troubleshooting can be performed as follows:
Check the configuration of the Ethernet Switch. Use the
■
command to view the ARP entry table that the Switch maintains.
Troubleshooting: First check which VLAN includes the port of the Switch used
■
to connect to the host. Check whether the VLAN has been configured with the
VLAN interface. Then check whether the IP address of the VLAN interface and
the host are on the same network segment.
If the configuration is correct, enable ARP debugging on the Switch, and check
■
whether the Switch can correctly send and receive ARP packets. If it can only
send but cannot receive ARP packets, there are possibly errors occurring on the
Ethernet physical layer.
Necessity of ARP
An IP address cannot be directly used for communication between network
devices because network devices can only identify MAC addresses. An IP address is
an address of a host in the network layer. To send the data packets transmitted
through the network layer to the destination host, the physical address of the host
is required. So the IP address must be resolved into a physical address.
ARP Implementation Procedure
When two hosts on the network communicate, they must know the MAC
addresses of each other. Every host will maintain the IP-MAC address translation
table, which is known as ARP mapping table. A series of maps between IP
addresses and MAC addresses of other hosts which were recently used to
communicate with the local host are stored in the ARP mapping table. When a
Switch
ARP Configuration 87
display arp