Qtech QSW-3300-28F-AC-AC [516/693] Arp dynamicrenew

Qtech QSW-3300-28F-AC-AC [516/693] Arp dynamicrenew
Address Resolution Protocol Commands
Software User Manual
CLI Command Reference
Page 533
arp dynamicrenew
This command enables the ARP component to automatically renew dynamic ARP entries when they age out.
When an ARP entry reaches its maximum age, the system must decide whether to retain or delete the entry. If
the entry has recently been used to forward data packets, the system will renew the entry by sending an ARP
request to the neighbor. If the neighbor responds, the age of the ARP cache entry is reset to 0 without removing
the entry from the hardware. Traffic to the host continues to be forwarded in hardware without interruption. If the
entry is not being used to forward data packets, then the entry is deleted from the ARP cache, unless the
dynamic renew option is enabled. If the dynamic renew option is enabled, the system sends an ARP request to
renew the entry. When an entry is not renewed, it is removed from the hardware and subsequent data packets
to the host trigger an ARP request. Traffic to the host may be lost until the router receives an ARP reply from
the host. Gateway entries, entries for a neighbor router, are always renewed. The dynamic renew option applies
only to host entries.
The disadvantage of enabling dynamic renew is that once an ARP cache entry is created, that cache entry
continues to take space in the ARP cache as long as the neighbor continues to respond to ARP requests, even
if no traffic is being forwarded to the neighbor. In a network where the number of potential neighbors is greater
than the ARP cache capacity, enabling dynamic renew could prevent some neighbors from communicating
because the ARP cache is full.
no arp dynamicrenew
This command prevents dynamic ARP entries from renewing when they age out.
arp purge
This command causes the specified IP address to be removed from the ARP cache . Only entries of type
dynamic or gateway are affected by this command.
\
Default disabled
Format
arp dynamicrenew
Mode Privileged EXEC
Format
no arp dynamicrenew
Mode Privileged EXEC
Format
arp purge ipaddress interface {unit/slot/port | vlan id}
Mode Privileged EXEC
Parameter Description
ipaddress The IP address to remove from the ARP cache.
vrf-name The virtual router from which IP addresses will be removed.
interface The interface from which IP addresses will be removed.

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