Arp Learning Via Gratuitous Arp - Dell Force10 C150 Configuration Manual

Command Syntax
clear arp-cache [
interface
ip-address] [ no-refresh ]

ARP Learning via Gratuitous ARP

Gratuitous ARP can mean an ARP request or reply. In the context of ARP Learning via Gratuitous ARP on
FTOS, the gratuitous ARP is a request. A Gratuitous ARP Request is an ARP request that is not needed
according to the ARP specification, but one that hosts may send to:
• detect IP address conflicts
• 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
fields.
In FTOS versions prior to 8.3.1.0, if a gratuitous ARP is received some time after an ARP request is sent,
only RP2 installs the ARP information. For example:
1. At time t=0 FTOS sends an ARP request for IP A.B.C.D
2. At time t=1 FTOS receives an ARP request for IP A.B.C.D
3. At time t=2 FTOS installs an ARP entry for A.B.C.D only on RP2.
Command Mode
| ip EXEC privilege
Purpose
Clear the ARP caches for all interfaces or for a specific
interface by entering the following information:
• For a 1-Gigabit Ethernet interface, enter the keyword
GigabitEthernet followed by the slot/port information.
• For a port channel interface, enter the keyword
port-channel followed by a number from 1 to 255 for
TeraScale and ExaScale, 1 to 32 for EtherScale.
For a SONET interface, enter the keyword sonet
•
followed by the slot/port information.
• For a 10-Gigabit Ethernet interface, enter the keyword
TenGigabitEthernet followed by the slot/port
information.
For a VLAN interface, enter the keyword vlan followed
•
by a number between 1 and 4094.
E-Series ExaScale platforms support 4094 VLANs
with FTOS version 8.2.1.0 and later. Earlier
ExaScale supports 2094 VLANS.
ip ip-address
(OPTIONAL) Enter the keyword ip followed by
the IP address of the ARP entry you wish to clear.
no-refresh
(OPTIONAL) Enter the keyword
delete the ARP entry from CAM. Or use this option with
ip ip-address
or
to specify which dynamic ARP entries you
want to delete.
Note: Transit traffic 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.
no-refresh
to
interface
IPv4 Addressing | 473