Re: ipv6nd-02.txt & autoconfig

["Eric W. Gray" <[e-mail]>]

This has somehow become a discussion of the use of SEL in ATM
addresses (doesn't follow from heading exactly).

	A little of what I've run into WRT the use of SEL.  It is up
to the end station how (and even if) this is used.  Therefore, unless
you somehow have control of a really large number of implementers, it
doesn't make (a lot of) sense to speculate on the philosophy of SEL 
usage.

	An application will want to use a different value for SEL any
time that it wants to register or advertise a service that requires a
unique ATM address - if the default SEL has already been used for that
purpose (with some other service).  That service might be support for 
multiple protocol specific addresses for any given protocol.  It might
also be for multiple service entities within the same protocol.

	An application might also want to use a different value for SEL
if it wants to avoid sticky situations that might arise as a result of
some clever user's efforts to re-use an existing connection rather than
establish a new one by forcing this user to treat the address as if it
were a completely different physical entity.

	In any case, SEL cannot be used unless the NIC (and its drivers)
allows an application to set/advertise its value (e.g. via calling party
address in setup and add party messages) and "register" to be notified
of incoming calls to that address.  Where-ever this capability exists,
however, philosophy will have little to do with its use.

--
Eric Gray