Administrator Guide

ARP
The system uses two forms of address resolution: address resolution protocol (ARP) and Proxy ARP.
ARP runs over Ethernet and enables endstations to learn the MAC addresses of neighbors on an IP network. Over time, the system
creates a forwarding table mapping the MAC addresses to their corresponding IP address. This table is called the ARP Cache and
dynamically learned addresses are removed after a defined period of time.
For more information about ARP, refer to RFC 826, An Ethernet Address Resolution Protocol.
Proxy ARP enables hosts with knowledge of the network to accept and forward packets from hosts that contain no knowledge of the
network. Proxy ARP makes it possible for hosts to be ignorant of the network, including subnetting.
For more information about Proxy ARP, refer to RFC 925, Multi-LAN Address Resolution, and RFC 1027, Using ARP to Implement
Transparent Subnet Gateways.
Configuration Tasks for ARP
For a complete listing of all ARP-related commands, refer to the Dell Networking OS Command Line Reference Guide.
Configuration tasks for ARP include:
• Configuring Static ARP Entries (optional)
• Configuring ARP Inspection Trust
• Configuring ARP Retries
• Configuring the Timer for Resending Unresolved ARPs
• Enabling Proxy ARP (optional)
• Clearing ARP Cache (optional)
• ARP Learning via Gratuitous ARP
• ARP Learning via ARP Request
• Configuring ARP Retries
Configuring Static ARP Entries
ARP dynamically maps the MAC and IP addresses, and while most network host support dynamic mapping, you can configure an ARP
entry (called a static ARP) for the ARP cache.
To configure a static ARP entry, use the following command.
• Configure an IP address and MAC address mapping for an interface.
CONFIGURATION mode
arp ip-address mac-address interface
• ip-address: IP address in dotted decimal format (A.B.C.D).
• mac-address: MAC address in nnnn.nnnn.nnnn format.
• interface: enter the interface type.
• For the Management interface, enter the keyword ManagementEthernet then the slot/port information. The slot range is
from 0 to 1 and the port range is 0.
• For a Port Channel interface, enter the keywords portchannel then a number. The range is from 1 to 128.
• For a 10-Gigabit Ethernet interface, enter the keyword TenGigabitEthernet then the slot/port information.
• For a 40-Gigabit Ethernet interface, enter the keyword fortyGigE then the slot/port information.
• For a port extender (PE) Gigabit Ethernet interface, enter the keyword peGigE then the pe-id/stack-unit /port-id
information. The pe-id is a port-extender ID number from 0 to 255; the stack-unit unit-number is from 0 to 7; and the port-id
range is from 1 to 48.
• For a port extender 10-Gigabit Ethernet interface, enter the keyword peTenGigE then the pe-id / stack-unit / port-id
information. The pe-id range is from 0 to 255; the stack-unit unit-number range is from 0 to 7; and the port-id range is 25 to
28 or 49 to 52 depending on the PE.
These entries do not age and can only be removed manually. To remove a static ARP entry, use the no arp ip-address command.
To view the static entries in the ARP cache, use the show arp static command in EXEC privilege mode.
Dell#show arp
440
IPv4 Routing