Users Guide

Address Resolution Protocol
Address Resolution Protocol (ARP) runs over Ethernet and enables end stations to learn the MAC addresses of neighbors on an IP
network. Using ARP, OS10 automatically updates the ARP cache table that maps the MAC addresses to their corresponding IP addresses.
The
ARP cache enables dynamically learned addresses to be removed after a time period you configure.
Configure static ARP entries
You can manually configure static entries in the ARP mapping table. Dynamic ARP is vulnerable to spoofing. To avoid spoofing, configure
static entries. Static entries take precedence over dynamic ARP entries.
NOTE: In the default forwarding-table mode, the maximum number of ARP entries that are learnt over Layer3 port-
channels is limited to 32000. This restriction is applicable only to the Z9100 and S5200.
1. Configure an IP address and MAC address mapping for an interface in INTERFACE mode.
ip arp ip-address mac address
• ip-address—IP address in dotted decimal format in A.B.C.D format.
• mac address—MAC address in nnnn.nnnn.nnnn format
These entries do not age, and you can only remove them manually. To remove a static ARP entry, use the no arp ip-address
command.
Configure static ARP entries
OS10(config)# interface ethernet 1/1/6
OS10(conf-if-eth1/1/6)# ip arp 10.1.1.5 08:00:20:b7:bd:32
View ARP entries
OS10# show ip arp interface ethernet 1/1/6
Address Hardware address Interface Egress Interface
--------------------------------------------------------------
10.1.1.5 08:00:20:b7:bd:32 ethernet1/1/6 ethernet1/1/6
IPv4 routing commands
clear ip arp
Clears the dynamic ARP entries from a specific interface or optionally delete (no-refresh) ARP entries from the content addressable
memory (CAM).
Syntax
clear ip arp [vrf vrf-name] [interface interface | ip ip-address] [no-refresh]
Parameters
• vrf vrf-name — (Optional) Enter vrf then the name of the VRF to clear ARP entries corresponding to
that VRF.
• interface interface— (Optional) Specify an interface type:
• ethernet — Physical interface.
•
port-channel — Port-channel identifier.
• vlan — VLAN identifier.
• loopback — Loopback interface identifier.
• virtual-network vn-id — Virtual network ID.
• ip ip-address — (Optional) Specify the IP address of the ARP entry to clear.
• no-refresh — (Optional) Delete the ARP entry from CAM. You can also use this option with interface
or ip ip-address to specify which dynamic ARP entries to delete.
Default Not configured
Command Mode EXEC
Usage Information Transit traffic may not forward during the period when deleted ARP entries resolve again and re-install in CAM.
NOTE: Use this option with extreme caution.
586 Layer 3