08-11-2009 07:46 AM - edited 03-06-2019 07:11 AM
It appears (to me at least) that the documentation (Command References) and command lookup tool provide elusive/and almost contradict each other on what the default behavior is) for:
no ip gratuitous-arps
ip gratuitous-arps
On top of that it appears that Cisco does not support these
commands on certain IOS based Catalysts.
I thought (most likely incorrect) that 'ip gratuitous-arps' were enabled by default through 12.2?
12.3 on - no ip gratuitous-arps was the default
end of story.
Can someone please provide accurate information on this
or point me in the right direction?
Jim Abercromby
08-11-2009 09:21 AM
Use this command reference for IOS:
http://www.cisco.com/en/US/docs/ios/ipaddr/command/reference/iad_arp.html#wp1013090
For Catalyst, the feature dynamic arp inspection does this:
08-11-2009 09:53 AM
Let me make sure I have this straight
For IOS/Router platforms = 'ip gratuitous arps'
disabled by default since 12.2
For Catalyst/Switch (MLS) etc. = 'ip arp inspection'
This is disabled by default too.
So if I am looking to see if a catalyst switch is
filtering/restricting gratuitous arps
'ip arp inspection filter vlan' commands
filtering specific vlans would have to be configured.
YES or NO?
08-11-2009 10:49 AM
1. NO: For IOS/ROUTERS, by default, if no command is entered:
Gratuitous ARP messages are NOT sent out when the client receives the address from the local address pool.
2. YES for Catalyst, Dynamic Arp Inspection, not enabled by default
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