Deployment Guide
• no-refresh (OPTIONAL): enter the keywords no-refresh to delete the ARP entry from CAM. Or to specify which dynamic
ARP entries you want to delete, use this option with interface or ip ip-address.
• For a port channel interface, enter the keywords port-channel then a number from 1 to 128.
• For a 10-Gigabit Ethernet interface, enter the keyword TenGigabitEthernet then the slot/port information.
• For a VLAN interface, enter the keyword vlan then a number between 1 and 4094.
NOTE: Transit trac may not be forwarded during the period when deleted ARP entries are resolved again and re-installed in
CAM. Use this option with extreme caution.
ARP Learning via Gratuitous ARP
Gratuitous ARP can mean an ARP request or reply.
In the context of ARP learning via gratuitous ARP on the system, the gratuitous ARP is a request. A gratuitous ARP request is an ARP
request that is not needed according to the ARP specication, but one that hosts may send to. Gratuitous ARP can:
• detect IP address conicts
• inform switches of their presence on a port so that packets can be forwarded
• update the ARP table of other nodes on the network in case of an address change
In the request, the host uses its own IP address in the Sender Protocol Address and Target Protocol Address elds. When a gratuitous ARP
is received, the system installs an ARP entry on the CPU.
To enable ARP learning via gratuitous ARP, use the arp learn-enable command in CONFIGURATION mode.
ARP Learning via ARP Request
In the Dell Networking OS versions prior to 8.3.1.0, the system learns via ARP requests only if the target IP specied in the packet matches
the IP address of the receiving router interface. This is the case when a host is attempting to resolve the gateway address.
If the target IP does not match the incoming interface, the packet is dropped. If there is an existing entry for the requesting host, it is
updated.
Figure 51. ARP Learning via ARP Request
Beginning with the Dell Networking OS version 8.3.1.0, when you enable ARP learning via gratuitous ARP, the system installs a new ARP
entry, or updates an existing entry for all received ARP requests.
IPv4 Routing
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