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dragonflymr's avatar
dragonflymr
Icon for Cirrostratus rankCirrostratus
Feb 09, 2015

Gratuitous ARP - how it's working

Hi,   I did some research about Gratuitous ARP (GARP) on the Internet and in F5 docs as well as did some tcdumps on my test system. I am not network expert so maybe it's obvious question but I can...
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Saskia_81056's avatar
Saskia_81056
Icon for Nimbostratus rankNimbostratus
Feb 12, 2015

ARP = Layer 3. All L3 devices in this L2 broadcast domain will process the GARP by putting the new MAC<->IP mapping into their ARP table. They don't care if there has been a request or not (which is why it can be easily used for spoofing)

 

Regarding the switches (L2): They don't really care about the GARP. The only sideway effect of the whole GARP thing is: As soon as the GARP frame arrives at the switch, it will learn the source MAC of this packet. Because of this, the switch will update its MAC address table.

 

dragonflymr's avatar
dragonflymr
Icon for Cirrostratus rankCirrostratus
Feb 12, 2015
Well, I guess testing using win platform was not the best choice, will play with linux to see how it works :-) Piotr