Subject: Re: Peculiar ICMP6 redirect rejection
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: William Waites <email@example.com>
Date: 08/19/2002 10:41:53
>>>>> "derMouse" == der Mouse <mouse@Rodents.Montreal.QC.CA> writes:
>> to be clear: i can't make any advice as you are using way too
>> strange configuration (trying to make address portable across
>> subnets using RIPng, nonstandard netmasks, and more).
derMouse> As for nonstandard netmasks, I'm not sure what's
derMouse> "nonstandard" about any of the netmasks I'm using,
derMouse> possibly excepting using a /128 on a broadcast
Might I suggest putting that /128 on the loopback interface and then
advertise it as reachable through the LL address of your ethernet NIC?
derMouse> if it makes you happier, I can go to a /127
derMouse> or /126 there. It's not terribly helpful to say
derMouse> something like that without indicating what a "standard"
derMouse> netmask is, or at least a pointer to where I can find
derMouse> that information.
I believe itojun was referring to the standard practice of making a
derMouse> a /112 or /128 netmask in some sense, then I have to
derMouse> ask, why on earth not?? What does it break, and what
derMouse> should I do instead?
It would certainly break the eui64 calculation, but you are assigning
addresses manually so that shouldn't be a problem. It seems like a
/112 should work, but it may cause some subtle issues that I don't
properly understand. I too would be interested to know exactly what it
>> i don't understand why you cannot following the normal
>> configuration practices.
derMouse> Principally, because I have no idea what you consider
derMouse> "normal configuration practices". I've basically just
derMouse> been mapping my v4 knowledge over in what appear to me
derMouse> to be the obvious ways, adjusting it as I run into the
derMouse> places where v4 and v6 differ.
Standard subnet size is /64. Wasteful of bits? Maybe. It does work
though. If you are trying to make sure your address is portable across
subnets, the address doesn't belong on a physical subnet, IMO. You
want to use whatever is the local network on your ethernet, and then
advertise reachability to an address that lives on the loopback
interface -- the global, or portable one. Except for the subnet size,
the same strategy works well with v4. I see no real difference.