[[e-mail]: Protocol Action: Character MIBs to Proposed Standard]

[Bob Stewart <[e-mail]>]

Into the home stretch...

----------- Forwarded Message

From: Internet Engineering Steering Group <[e-mail]>
To: Bob Braden <[e-mail]>, Internet Activities Board <[e-mail]>
Cc: Internet Engineering Task Force <[e-mail]>
Subject: Protocol Action: Character MIBs to Proposed Standard
Date: Tue, 11 Feb 92 16:37:39 -0500
Sender: [e-mail]


Recommendation:

The IESG recommends to the IAB that the Internet Drafts 

"Definitions of Managed Objects for RS-232-like Hardware Devices"
	<draft-ietf-charmib-rs232like-03>, 

"Definitions of Managed Objects for Parallel-printer-like Hardware
	Devices" <draft-ietf-charmib-parallelprinter-02>, and 

"Definitions of Managed Objects for Character Stream Devices"
	<draft-ietf-charmib-charmib-02> 

be published as Proposed Standards.  These documents are the products
of the Character MIB Working Group of the IETF.

Technical Summary:

The following diagram shows two possible "MIB stacks", each using a
different combination of existing MIB specifications:

                                   .-----------------.
        .-----------------.        |  Standard MIB   |
        |   Telnet MIB    |        | Interface Group |
        |-----------------|        |-----------------|
        |  Character MIB  |        |     PPP MIB     |
        |-----------------|        |-----------------|
        | RS-232-like MIB |        | RS-232-like MIB |
        `-----------------'        `-----------------'

The RS-232-like MIB and the Parallel-printer-like MIB represent the
physical layer, providing service to higher layers such as the
Character MIB or PPP MIB.  Further MIBs may appear above these.

The intent of the model is for the physical-level MIBs to represent
the lowest level, regardless of the higher level that may be using it.
In turn, separate higher level MIBs represent specific applications,
such as a terminal (the Character MIB) or a network connection (the
PPP MIB).

For the most part, character ports are distinct from network
interfaces (which are already instrmented by the Interfaces group of
MIB 2).  In general, they are attachment points for non-network
devices.  The exception is a character port that can support a network
protocol, such as SLIP or PPP.  This implies the existence of a
corresponding entry in the Interfaces table, with ifOperStatus of
'off' while the port is not running a network protocol and 'on' if it
is.  The intent is that such usage is exclusive of non-network
character stream usage.  That is, while switched to network use,
charPortOperStatus would be 'down' and Character MIB operational
values such as charPortInFlowState and charPortInCharacters would be
inactive.


PARALLEL-PRINTER-LIKE MIB

The Parallel-printer-like MIB includes Centronics, Data Products, and
other parallel physical links with a similar set of control signals.

The MIB contains objects that relate to physical layer connections.
Such connections may provide interesting hardware signals (other than
for basic data transfer), such as Power and PaperOut.

The Parallel-printer-like MIB is mandatory for all systems that have
such a hardware port supporting services managed through some other
MIB, for example, the Character MIB.

RS-232-LIKE MIB

The RS-232-like Hardware Device MIB is mandatory for all systems that
have such a hardware port supporting services managed through some
other MIB, for example, the Character MIB or PPP MIB.

The RS-232-like Hardware Port MIB includes RS-232, RS-422, RS-423,
V.35, and other asynchronous or synchronous, serial physical links
with a similar set of control signals.

The MIB contains objects that relate to physical layer connections.
Such connections may provide interesting hardware signals (other than
for basic data transfer), such as RNG and DCD.  Hardware ports also
have such attributes as speed and bits per character.

Usefulness of the error counters in this MIB depends on the presence
of non-error character counts in higher level MIBs.

CHARACTER MIB

The Character MIB applies to interface ports that carry a character
stream, whether physical or virtual, serial or parallel, synchronous
or asynchronous.  The most common example of a character port is a
hardware terminal port with an RS-232 interface.  Another common
hardware example is a parallel printer port, say with a Centronics
interface.  The concept also includes virtual terminal ports, such as
a software connection point for a remote console.

The Character MIB is mandatory for all systems that offer character
ports.  This includes, for example, terminal servers, general-purpose
time-sharing hosts, and even such systems as a bridge with a (virtual)
console port.  It may or may not include character ports that do not
support network sessions, depending on the system's needs.

The Character MIB's central abstraction is a port.  Physical ports
have a one-to-one correspondence with hardware ports.  Virtual ports
are software entities analogous to physical ports, but with no
hardware connector.

Each port supports one or more sessions.  A session represents a
virtual connection that carries characters between the port and some
partner.  Sessions typically operate over a stack of network
protocols.  A typical session, for example, uses Telnet over TCP.

The MIB intentionally contains no distinction between what is often
called permanent and operational or volatile data bases.  For the
purposes of this MIB, handling of such distinctions is implementation
specific.