jamal wrote: >>> Sorry for chiming in this late in the discussion, but... Shouldn't it >>> be more correct to not depend on the ip address of the used network, >>> but to use the "scope" parameter of the given address? > > Excellent point! It was bothering me as well but i couldnt express my > view eloquently as you did.
Explicitly defining scope may indeed be a better approach at first sight, but there are a few very practical reasons not to use them. First, it would not be useful in this purpose. IPv6 link-local addresses (FE80::0/10 addresses) are "local" in scope, just like the IPv4 link-local addresses, but ARP replies for IPv6 should not be broadcasted (since there are no address conflicts due to the larger address space). Secondly, this is matter of choice: either the IP address or the "scope" parameter is authoritative when it comes to specific behaviour of network devices. It'd say that since the IETF and IANA specifically use IP addresses, we should follow that guideline. To elaborate on my last point: The alternative would be to require all application that set an IP address to also set the scope. This is currently not done. Adding three machine instructions is just the easier approach. Of course, in some cases the "easy" solution is not always best, but in this case I argue it is. There are IP ranges which are threated as special (see RFC 3330 for IPv4 and RFC 4291 for IPv6). In my opinion, this means there is a strict relation from IP address to scope; defining scope inconsistent with the IP range seems like bad practice to me. For example, using 1.1.1.0/24 would break if IANA would decide to assign that range, and using 10.0.0.0/8 in public networks would simple not work. If someone uses private IP ranges, that's regarded as harmful traffic, and machines of the AS112 project will deal with it (they deploy machines, which you can regard as the /dev/null of the Internet). In short, while scope may be a better argument then ranges, I would not deviate from Internet standards, and would advise against using them both (please refer to the complexity arguments as put forward in "Robustness and the Internet" by Walter Willinger and John Doyle, or simply RFC 1958 and RFC 3439). (*) With regards, Freek Dijkstra (*) Note: using this argument, it is easy to argue that special cases like the proposed patch are bad, and I agree. From a scientific point of view, I would much prefer that everyone use IPv6 and abandon IPv4 yesterday. Unfortunately, that's not practical. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
