We had an instance where a piece of equipment failed that was connected to our 6509 switch. When we replaced the unit with same make and model, the device could not ping outside the VLAN. We performed a sh arp and then a sh mac-address-table | i
++ show arp will show you your Ethernet/ARPA/MAC addresses which are mapped to IP addresses for the hosts
which have previously ARPed your router.
++ They basically display the same info. The show arp will show you not only your IP-MAC, but other L3-MAC addresses, e.g. Appletalk.
++ While show ip arp , will by definition show you only your IP-MAC bindings.
Please click here for documentation on IP Addressing commands
++ Clear arp & clear ip arp removes the output of show arp & show ip arp respectively
clear ip arp
++ By default the arp timeout is 4 hours and mac address table timeout is 300 seconds.
++ when you issued clear arp-cache/clear arp/clear ip arp, the relevant arp table output should clear.
In addition to clearing the ARP cache, the clear arp-cache causes the particular device to send a gratuitous ARP reply regarding its own address - usable if for whatever reason, the MAC address of the device changes. The clear ip arp does not send gratuitous ARPs.
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