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... -Brad ----- Original Message ----- From: "James A. Crippen" <james@UnLambda.COM> To: "Brad Bonkoski" <bbonkoski@xyterra.com> Cc: <linux-net@vger.kernel.org> Sent: Monday, August 13, 2001 11:59 AM Subject: Re: ARP > On Mon, 13 Aug 2001, Brad Bonkoski wrote: > > > Hello All, > > > > What is the difference between gratuitous ARP and RARP? > > Not sure what you mean by 'gratuitous'. ARP is 'Address Resolution > Protocol', and is used to resolve link layer (eg, ethernet) addresses that > map to known network layer (eg, IP) addresses. > > RARP is 'Reverse Address Resolution Protocol', and is used to resolve in > the opposite direction, from known link layer addressses to unknown > network layer addresses. > > ARP is used for instance to find the ethernet address for a host on a > directly connected network. An example is when the system hunts for its > default gateway. Before it can send traffic it has to know the ethernet > address for the target host, so it sends an ARP request to the ethernet > broadcast address (ff:ff:ff:ff:ff:ff in ethernet) which is then seen by > all hosts on the segment. The host which has the IP address listed in > that ARP request then replies directly (not using broadcast) to the > originating machine with an ARP reply. > > If you want to see a simple example of this then get a traffic sniffer > such as Ethereal (http://www.ethereal.com) and try watching traffic on > your own network. Look for ARP requests and follow the transaction. > > 'james > > -- > James A. Crippen <james@unlambda.com> ,-./-. Anchorage, Alaska, > Lambda Unlimited: Recursion 'R' Us | |/ | USA, 61.2069 N, 149.766 W, > Y = \f.(\x.f(xx)) (\x.f(xx)) | |\ | Earth, Sol System, > Y(F) = F(Y(F)) \_,-_/ Milky Way. - : 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
