Its not a typo. Its a request for its own IP. Gratuitous arps are essentially a self arp i.e. think of the host advertising its own mac address/ip address. The host sending out a garp can detect a duplicate IP if it receives a reply (it should not normally receive a reply to its own address). It can also be used to advertise a new MAC address which comes in very handy in failover situations and clustering solutions. Hope that helps, thanks, Nivedita > > On Mon, 13 Aug 2001, Brad Bonkoski wrote: > > > Okay, > > I know what ARP is.... > > Gratuitous ARP as defined in TCP/IP ILLUSTRATED VOL.1, The Protocols by W. > > Richard Stevens > > "It occurs when a host sends an ARP request looking for its own IP address. > > This is usually done when the interface is configured at bootstrap time." > > Now, to me, that sounds like RARP, bootp, etc... but I could be wrong. So, > > I ask you all. Of course I have never heard of this either, never was > > defined in my Comer TCP/IP books... > > That looks distincly like a typo. RARP requests are used to find a host's > network address. ARP requests are used to find a host's MAC address. He > probably meant RARP. Check the web page for that book and see if that's > listed as an erratum, and if not then get Stevens's address and mail him > about it. > > Nowadays most people handle BOOTP/RARP with the DHCP server from the ISC, > or similar. But the old crufty BOOTP server for Linux is still floating > around somewhere. IIRC ISC DHCP will handle BOOTP so you don't really > need the old BOOTP server to eg boot your dickless Sun workstation. > > HTH > 'james - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
