Joe, On Dec 3, 2013, at 7:54 AM, Joe Touch <[email protected]> wrote:
> > > On 12/3/2013 12:55 AM, Pedro Roque Marques wrote: >> Is the fundamental IP behavior that you are referring to the TTL decrement >> between two addresses on the same "subnet" ? >> I believe you are wrong: to my knowledge proxy ARP is compliant with Host >> and Router requirement RFCs. > > For IPv4, RFC1812 says that all 1's "limited broadcast" > (255.255.255.255) MUST NOT be forwarded. RFC2644 updates that RFC to say > that even subnet-directed broadcasts MUST NOT be forwarded (as > configured by default). > > So by default, a router would never forward the broadcast for which the > proxy ARP would be an appropriate response. yes. > Which would mean that the > proxy would work only if already populated at the router; I don't follow. Lets assume i've a device that is an IP compliant router which has interface A and interface B. The quote above means that it should not forward a packet address to 255.255.255.255 between link A and link B (or vice-versa). This has nothing no relationship to whether this device is capable of generating ARP requests or proxy ARP replies. > there would be > no means to forward the initial request if the cache were empty. So > proxy ARP would work if manually configured, but would be unreliable if > automatically populated if used on a router that spans two groups of > hosts on the same subnet. Proxy ARP is unrelated to subnet broadcasts. > > Joe >
