On Thu, Apr 14, 2022 at 12:38 PM Jürgen Schönwälder < j.schoenwael...@jacobs-university.de> wrote:
> On Thu, Apr 14, 2022 at 09:23:38AM -0700, Andy Bierman wrote: > > > > > So is this a correct summary: > > > > - zone index is not used in IPv4 at all > > There are link-local IPv4 addresses, they are less wide-spread since > IPv4 stacks generally do not auto-configure IPv4 link-local addresses. > Nobody will be able to confirm "not used at all", this questions is > somewhat rhetoric since nobody can answer it. > > > - zone index is not configured by a client in IPv6 at all > > Configuring zone indexes is required in many cases to reach services > that are only reachable via link-local addresses. I mentioned the DNS > resolver example and this applies to pretty much any transport layer > endpoint. This is why by design (and not by accident) the with zone > version of ip-address is used in the inet:host typedef. > > > - zone index is assigned by the system (as needed) to IPv6 link-local > > addresses > > A link-local address exists on a link and as such does not need a zone > index as long it is used on the link. However, when you want to refer > to a link-local address on a system with more than one link, then the > link-local address is ambiguous and to disambiguate things you either > specify in adding the interface to be used or you embed the zone index > in the address. Since application code usually assumes that a > transport address is an (ip-address, port) tuple, people converged on > adding the zone to the ip address (instead of rewriting all APIs to > use (ip-address, port, interface) tuples. The zoned IP address > notation is meanwhile widely supported. This is why we have, for > example, RFC 6874 (but the IPv6 folks have a reoccuring debate about > the question whether the % needs to be percent encoded or not, > draft-carpenter-6man-rfc6874bis-03). > > > I want to add a server option in our code to always reject (or alter) > > an edit that contains a zone index. I need to know the consensus on > > whether it is OK to ignore a zone index from a client. > > It is your choice to design a product that will not work with > link-local addresses. For IETF data models, I expect that the bar is > higher and that people can expect that IETF data models are written to > also work with link-local addresses. If implementers than decide that > their users do not need to work with link-local addresses, so be it, > you can make your server reject the optional zone index. But others > can decide that they customers can also work with link-local > addresses. If we blindly remove the zone index from ip-address, then > the IETF would break data models for those who consider link-local > addresses a first class citizen. > > A server option is useful for an implementation that does not support zone index configuration. It is an implementation detail so out of scope. The proposal is for a 2 year phase to change modules that really do want a zone index. It is not blindly removing the zone index. > Nothing in RFC 6241 suggests that this is OK for <edit-config>. > > I have no clue what you mean. If your server recceives a value that > your server does not support, you reject the value. > > /js > Andy > > PS: I recall the side meetings with IPv6 people to sort out how we add > proper IPv6 support to MIB modules, which led to RFC 4001, which > later influenced the YANG typedefs. Almost 20 years later (and > IPv6 deployed at a much larger scale) I find myself in a > discussion where people question that we need to support > link-local addresses. This is very irritating. > > Apparently, getaddrinfo() implementations tend to handle zoned > link-local addresses just fine and any code that passes a zoned ip > address string to getaddrinfo() will likely return you a socket > address with the sin6_scope_id filled in properly. You actually > have to do extra work to prevent the right thing to happen if your > code passes strings on to getaddinfo(). I am puzzled why people > want to do this. > > -- > Jürgen Schönwälder Jacobs University Bremen gGmbH > Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany > Fax: +49 421 200 3103 <https://www.jacobs-university.de/> >
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