Fred,
On 2012-03-22 13:29, Fred Baker wrote:
On Mar 21, 2012, at 10:51 PM, Brian E Carpenter wrote:
In other words if the IETF doesn't define the zone index, every
implementor will have to do so anyway. Also, read the last clause
carefully: it says the stack MUST allow OPTIONAL use of the zone
index internally.
Implementors generally *do* have some internal form of a zone index, and it
doesn't look at all like what the RFC describes. It is a machine address or a
lookup index of some kind for a table that is associated with an interface.
Sometimes, part of it is a card identifier.
Yes, someone recently cited fe-0/0/1 as a real-world example of an
interface identifier (in practice equivalent to a zone identifier)
RFC 4007 says nothing about the syntax of the identifier. Clearly
the mapping to a 32 bit integer is a local matter in the node; look
at RFC 4007 and the socket API together.
From MIF's perspective, if the same prefix is placed on multiple
interfaces,
The prefix fe80::/10 is automatically on every interface. That's the
only case where I'm certain we need a zone index in practice, but the
definition isn't limited to that case.
The use of something to get me to the interface table in question isn't what
I am questioning. It's the use of that particular something...
IMHO it is very limited, mainly for diagnostic use. We need to get
it right but it has no mainstream value that I can see.
Brian