Subranging InetAddressPrefixLength

["C. M. Heard" <heard@pobox.com>]

Howdy,

In the just-announced draft draft-ietf-ipv6-rfc2096-update-06.txt
this definition caugt my eye:

  inetCidrRoutePfxLen OBJECT-TYPE
      SYNTAX     InetAddressPrefixLength (0..128)
      MAX-ACCESS not-accessible
      STATUS     current
      DESCRIPTION
             "Indicates the number of leading one bits which
              form the mask to be logical-ANDed with the
              destination address before being compared to
              the value in the inetCidrRouteDest field.

              The values for the index objects inetCidrRouteDest
              and inetCidrRoutePfxLen must be consistent.  When
              the value of inetCidrRouteDest is x, then the bitwise
              logical-AND of x with the value of the mask formed
              from the corresponding index object inetCidrRoutePfxLen
              MUST be equal to x.  If not, then the index pair is not
              consistent and an inconsistentName error must be
              returned on SET or CREATE requests."
      ::= { inetCidrRouteEntry 3 }

If we discourage people from putting size constraints on InetAddress
objects and from putting value constraints on InetAddressType
objects, all in order to ensure future extensibility, it seems to
me that we should similarly discurage putting range restrictions on
InetAddressPrefixLength objects.

Neither RFC 3291 nor draft-3291bis addresses this explicitly;
maybe the next rev of 3291bis should do so.

Mike