Date: Tue, 16 Apr 2002 23:06:20 +0900
From: JINMEI Tatuya <[EMAIL PROTECTED]>
Message-ID: <[EMAIL PROTECTED]>
| If there's no other opinion on this point, I'll restrict the positive
| value in the revised text.
This is probably not important - but is there any real need to allow
the value -1 to actually be set?
That is, I fully understand why it is the default value, but if an
application decides it wants to use the minimium MTU (for unicast) or
that it doesn't (for multicast), is it really likely that it will
want to ever say (on one socket) "use it for multicast but not for
unicast" ?
Having that as the default makes sense, as there's no way to know in
the stack whether unicast or multicast packets will be sent, until
after they're sent. But the application sure knows... Do applications
really send both unicast and multicast packets out one socket?
I guess my point is that all that might need to be altered is the
default setting, no need to add the -1 value as a possible arg to the
syscall (if an app really needs to return to the default values, it
could just close the socket, open a new one, and bind it to the same
address).
If we do need the new value, then are we 100% sure that we're not also
going to need "use min mtu for unicast, but not for multicast" (the
4th possible case). I know that one seems crazy, but are we so certain
that it will never be needed that it shouldn't be provided? If we
assume that apps don't send unicast & multicast out the same socket,
then clearly it isn't needed (but nor is the ability to set -1). If
we assume that apps never send multicast other than min mtu, then it
isn't needed - but then IPV6_USE_MIN_MTU could simply be defined as
unicast only. And we already know that apps want to use min mtu for
unicast packets (that's why the thing exists in the first place).
So, from this, it seems to be, that if -1 exists (as a value that can
be set), -2 (or something) needs to exist as well...
kre
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