UMN:CLI
User Manual
V8102
268
8 System Security
8.1
Address Resolution Protocol (ARP)
Devices connected to IP network have two addresses, LAN address and network address.
LAN address is sometimes called as a data link address because it is used in Layer 2
level, but more commonly the address is known as a MAC address. A switch on Ethernet
needs a 48-bit-MAC address to transmit packets. In this case, the process of finding a
proper MAC address from the IP address is called an address resolution.
On the other hand, the progress of finding the proper IP address from the MAC address is
called reverse address resolution. Our switches and DSLAMs find their MAC addresses
from the IP addresses through Address Resolution Protocol (ARP). ARP saves these ad-
dresses in ARP table for quick search. Referring to the IP addresses in ARP table, the
packets containing the IP address are transmitted to network. When configuring the ARP
table, it is possible to do it only in some specific interfaces.
8.1.1
ARP Table
Hosts typically have an ARP table, which is a cache of IP/MAC address mappings. The
ARP Table automatically maps the IP address to the MAC address of a switch. In addition
to address information, the table shows the age of the entry in the table, the encapsula-
tion method, and the switch interface (VLAN ID) where packets are forwarded.
The V8102 ARP saves IP/MAC addresses mappings in ARP table for quick search. Refer-
ring to the information in ARP table, packets attached IP address is transmitted to network.
When configuring ARP table, it is possible to do it only in some specific interfaces.
8.1.1.1
Registering ARP Table
The contents of ARP table are automatically registered when MAC address corresponds
to IP address. The network administrator could use MAC address of specific IP address in
network by registering on ARP table.
To specify a static ARP entry, use the following command.
Command
Mode
Description
arp
A.B.C.D MACADDR
[
vlan
VLANID
]
Global
Specifies a static ARP entry.
MAC-ADDR: MAC address.
arp
A.B.C.D MACADDR INTER-
FACE
Specifies a static ARP entry with an interface name.
INTERFACE: interface name
MAC-ADDR: MAC address
no arp
[
A.B.C.D
]
Deletes static ARP entries.
no arp
A.B.C.D INTERFACE
