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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter22 Configuring IP Unicast Routing Configuring IP Addressing
You can perform these tasks to configure address resolution:
•Define a Static ARP Cache, page 22-11
•Set ARP Encapsulation, page 22-12
•Enable Proxy ARP, page 22-13
Define a Static ARP Cache
ARP and other address resolution protocols provide dynamic mapping between IP addresses and MA C
addresses. Because most hosts support dynamic address resolution, you usually do not need to specify
static ARP cache entries. If you must define a static ARP cache ent ry, you can do so gl ob ally, which
installs a permanent entry in the ARP cache that the switch uses to translate IP addresses into MAC
addresses. Optionally, you can also specify that the switch respond to ARP requests as if it were the
owner of the specified IP address. If you do not want the ARP entry to be permanent, you c an specify a
timeout period for the ARP entry.
Beginning in privileged EXEC mode, follow these steps to provide static mapping between IP addresses
and MAC addresses:
To remove an entry from the ARP cache, use the no arp ip-address ha rdware-ad dress ty p e global
configuration command. To remove all nonstatic entries from the ARP cache, use the clear arp-cache
privileged EXEC command.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 arp ip-address hardware-address type Globally associate an IP address with a MAC (hardware) add ress
in the ARP cache, and specify encapsulation type as one of
these:
•arpa—ARP encapsulation for Ethernet interfaces
•snap—Subnetwork Address Protocol encapsulation for
Token Ring and FDDI interfaces
•sap—HP’s ARP type
Step3 arp ip-address hardware-address type [alias] (Optional) Specify that the switch respond to ARP requests as if
it were the owner of the specified IP address.
Step4 interface interface-id Enter interface configuration mode, and specify the interface to
configure.
Step5 arp timeout seconds (Optional) Set the length of time an ARP cache entry will stay in
the cache. The default is 14400 seconds (4 hours). The range is
0 to 2147483 seconds.
Step6 end Return to privileged EXEC mode.
Step7 show interfaces [interface-id] Verify the type of ARP and the timeout value used on all
interfaces or a specific interface.
Step8 show arp
or
show ip arp
View the contents of the ARP cache.
Step9 copy running-config startup-config (Optional) Save your entries in the configuration file.