Re: Clear IP arp?

seems that is the case...

i never really thought about what this command was doing, but have
seen it and used it so much in enterprise networks on core devices
when swapping out computers and working with dhcp...

the little things that just sort of skip over i guess...

R1#sh debug
ARP:
  ARP packet debugging is on

R1#sh ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 12.12.12.1 - c200.177c.0000 ARPA FastEthernet0/0
Internet 12.12.12.2 50 c202.177c.0000 ARPA FastEthernet0/0

R1#clear ip arp 12.12.12.2

R1#
*Mar 1 20:58:04.962: IP ARP: sent req src 12.12.12.1 c200.177c.0000,
                 dst 12.12.12.2 c202.177c.0000 FastEthernet0/0
*Mar 1 20:58:05.030: IP ARP: rcvd rep src 12.12.12.2 c202.177c.0000,
dst 12.12.12.1 FastEthernet0/0
*Mar 1 20:58:05.034: IP ARP: creating entry for IP address:
12.12.12.2, hw: c202.177c.0000

R1#sh ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 12.12.12.1 - c200.177c.0000 ARPA FastEthernet0/0
Internet 12.12.12.2 0 c202.177c.0000 ARPA FastEthernet0/0

--
Garry L. Baker
"With sufficient thrust, pigs fly just fine..." - RFC 1925
On Mon, Sep 26, 2011 at 4:41 PM, Steve Di Bias <sdibias_at_gmail.com> wrote:
> Interesting info, does the same hold true when clearing individual ARP
> entries with the "clear ip arp x.x.x.x" command?
> On Sep 26, 2011 6:25 AM, "Joe Astorino" <joeastorino1982_at_gmail.com> wrote:
>> Indeed, I learned this and posted on it here a few months ago as well.
> When
>> you do "clear ip arp" it actually will look at every entry currently in
> the
>> table and send out an ARP for it, thereby refreshing the table. The only
>> way I know of to truly clear it is shut and no shut the interface.
>>
>> On Sun, Sep 25, 2011 at 12:50 PM, Nadeem Rafi <nrafia_at_gmail.com> wrote:
>>
>>> it does not clear cache at all, it just refresh it :)
>>> for detail check this link
>>> http://nadeemrafi.com/arp-arpa-and-snap-wow-110/
>>>
>>> On Sun, Sep 25, 2011 at 7:31 PM, Ted Sell <tedsell_at_gmail.com> wrote:
>>>
>>> > I have a few questions:
>>> > Why does the clear command not work as expected?
>>> > I tried to clear the arp-cache using the clear command. I watched a INE
>>> > video where the instructor tried the clear command, without success. He
>>> had
>>> > to shut and no shut the interface to get the cache to to clear for the
>>> > interface.
>>> > What does the clear command do when you're trying to clear the
> ARP-cache?
>>> > TIA,
>>> > Ted Schafer
>>> >
>>> >
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>>
>> --
>> Regards,
>>
>> Joe Astorino
>> CCIE #24347
>> Blog: http://astorinonetworks.com
>>
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>>
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