Le 24/02/2017 à 17:27, Christopher Morrow a écrit :
On Fri, Feb 24, 2017 at 10:48 AM, Alexandre Petrescu <alexandre.petrescu@xxxxxxxxx <mailto:alexandre.petrescu@xxxxxxxxx>> wrote: Le 24/02/2017 à 15:59, Christopher Morrow a écrit : On Fri, Feb 24, 2017 at 9:09 AM, Alexandre Petrescu <alexandre.petrescu@xxxxxxxxx <mailto:alexandre.petrescu@xxxxxxxxx> <mailto:alexandre.petrescu@xxxxxxxxx <mailto:alexandre.petrescu@xxxxxxxxx>>> wrote: A question to Windows is the following: what prefixlen does it set when the end user manually assigns an address on an interface without specifiying a prefixlen? I don't think this matters... 'end users' will in almost all cases just attach and get connectivity. Let me go next in cycle: what does linux do when one ifconfig add an IPv6 address without telling the plen? Is it adding an entry in the rt table? Which plen? Is that plen normal? still don't think this matters. If a user messes up what they type, they messed up. if the instructions aren't complete, they aren't complete and there will be mistakes. An interface configuration requires all proper parameters be set, or problems will arise. Assumptions about current and future behavior are proven wrong time and again. non-deterministic behavior over time is the hallmark of this space... please do not rely on defaults for hand-managed/bespoke configurations if you expect things to work reliably and repeatably.
That means the following: Windows please make the plen parameter mandatory. Dont leave it optional only to subversively set it to 64. That's a software bug because nobody asks you to set the plen to 64 when the end user does not specify one. I guess the same bug is is in BSD, linux and what have you.
If they are in a place where someone says: "Hey, you should go if/ipconfig ...." then .. they are 'consenting adults' and can do whatever they please. I assume you assume that ip/ifconfig by consenting adults means the adults type a plen in the CLI, right? sure, or a script/program/etc does this, it's not important how the 'ifconfig' happens, it's important that when it happens the right parameters are passed to the 'ifconfig' command.
I agree. If 'ifconfig' silently assumes 64 then that assumption is wrong. The ifconfig programmer should take that as a software bug. It's not an RFC that requires them to put 64 there.
That makes it mandatory that the CLI _requires_ a plen, right? That CLI should not allow silence for a plen parameter. sure, or you are at the mercy of the implementor of that command: Today I like /64! It's tomorrow and now I like /62!! don't rely on defaults.
I agree.
Because silent plen means 64. And I dont think it's right to assume a by-default 64 plen. Because many people think 64 is right and others think it's wrong, there does not seem to be a commonly agreed 'by default' value for plen. correct, so.. be specific in your configuration effort please... which again, means that the 'what is the default?" conversation is moot.
I am not asking what is the default. I am saying that apparently numerous implementations out there consider the default to be 64. This consideration is wrong. A 'default' value is something that everybody agrees with. For example, one can leave out '::' from a command line adding a default route and just say 'default'. There is an agreed standard that says that 'default' is '::'. But there is by far no single standard that says the default prefix length is 64. That's why it's a bug. It's like boxes with pre-defined passwords admin/admin. The local programmer imagined it a good 'default' but never asked around the validity of such assumption. And that creates problems. Alex
Alex again the proposed text (now 175+ messages back) really covers this already..