In order to minimize the instrumentation burden on managed agents, the MIB definitions produced by the working group will, wherever feasible, be semantically consistent with the managed objects defined in the IEEE draft standard P802.3K, ``Layer Management for hub Devices.'' The working group will base its work on the draft that is the output of the July 1991 IEEE 802 plenary meeting. The working group will take special cognizance of Appendix B of that specification that sketches a possible realization of the relevant managed objects in the SNMP idiom.
Consistent with the IETF policy regarding the treatment of MIB definitions produced by other standards bodies, the working group may choose to consider only a subset of those objects in the IEEE specification and is under no obligation to consider (even for ``Optional'' status) all objects defined in the IEEE specification. Moreover, when justified by special operational needs of the community, the Working Group may choose to define additional MIB objects that are not present in the IEEE specification.
Although the definitions produced by the working group should be architecturally consistent with MIB-II and related MIBs wherever possible, the charter of the working group does not extend to perturbing the conceptual models implicit in MIB-II or related MIBs in order to accommodate 802.3 hubs. In particular, to the extent that the notion of a ``port'' in an 802.3 hub is not consistent with the notion of a network ``interface'' as articulated in MIB-II, it shall be modelled independently by objects defined in the working group.
Because the structure of 802.3 hub implementations varies widely, the working group shall take special care that its definitions reflect a generic and consistent architectural model of hub management rather than the structure of particular hub implementations.
The IEEE hub Management draft allows an implementor to separate the ports in a hub into groups, if desired (i.e., a vendor might choose to represent field-replaceable units as groups of ports so that the port numbering would match a modular hardware implementation). Because the working group charter does not extend to consideration of fault-tolerant, highly-available systems in general, its treatment of these groups of ports in an 802.3 hub (if any) shall be specific to hub management and without impact upon other portions of the MIB.
The working group is further chartered at its discretion to define an SNMP MIB for management of IEEE 802.3 Medium Access Units (MAUs). An 802.3 Medium Attachment Unit (MAU) attaches a repeater port or Ethernet-like interface to the local network medium. The scope of this work may include several types of MAU units: 10BASE-5 (thick coax), 10BASE-2 (thin coax), 10BASE-T (twisted pair), FOIRL and 10BASE-F (fiber optic). Managed objects defined as part of the MAU MIB task may, for example, represent such information as MAU type, link status, and jabbering indications.