3Com Switch 4210 9-Port, Configuration Manual

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278 C
HAPTER
23: ARP C
ONFIGURATION
ARP Table 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 Switch 4210 provides the
display arp command to display the
information about ARP mapping entries.
ARP entries in the Switch 4210 can either be static entries or dynamic entries, as
described in Table 212.
Table 210 Description of the ARP packet fields
Field Description
Hardware Type Type of the hardware interface. Refer to
Table 211 for the information about the field
values.
Protocol type Type of protocol address to be mapped.
0x0800 indicates an IP address.
Length of hardware address Hardware address length (in bytes)
Length of protocol address Protocol address length (in bytes)
Operator Indicates the type of a data packets, which
can be:
■
1: ARP request packets
■
2: ARP reply packets
■
3: RARP request packets
■
4: RARP reply packets
Hardware address of the sender Hardware address of the sender
IP address of the sender IP address of the sender
Hardware address of the receiver
■
For an ARP request packet, this field is null.
■
For an ARP reply packet, this field carries
the hardware address of the receiver.
IP address of the receiver IP address of the receiver
Table 211 Description of the values of the hardware type field
Value Description
1 Ethernet
2 Experimental Ethernet
3 X.25
4 Proteon ProNET (Token Ring)
5 Chaos
6 IEEE802.X
7 ARC network
Table 212 ARP entries
ARP entry Generation Method Maintenance Mode
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.