Network Working Group B. Stewart, Editor
Request for Comments: 1316 Xyplex, Inc.
April 1992
This RFC specifies an IAB standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited.
This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in TCP/IP based internets. In particular it defines objects for the management of character stream devices.
The Internet-standard Network Management Framework consists of three components. They are:
RFC 1155 which defines the SMI, the mechanisms used for describing and naming objects for the purpose of management. RFC 1212 defines a more concise description mechanism, which is wholly consistent with the SMI.
RFC 1156 which defines MIB-I, the core set of managed objects for the Internet suite of protocols. RFC 1213, defines MIB-II, an evolution of MIB-I based on implementation experience and new operational requirements.
RFC 1157 which defines the SNMP, the protocol used for network access to managed objects.
The Framework permits new objects to be defined for the purpose of experimentation and evaluation.
Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are
defined using the subset of Abstract Syntax Notation One (ASN.1) [7]
defined in the SMI. In particular, each object has a name, a syntax,
and an encoding. The name is an object identifier, an
administratively assigned name, which specifies an object type.
The object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience, we often use a textual string, termed the OBJECT DESCRIPTOR, to also refer to the object type.
The syntax of an object type defines the abstract data structure corresponding to that object type. The ASN.1 language is used for this purpose. However, the SMI [3] purposely restricts the ASN.1 constructs which may be used. These restrictions are explicitly made for simplicity.
The encoding of an object type is simply how that object type is represented using the object type's syntax. Implicitly tied to the notion of an object type's syntax and encoding is how the object type is represented when being transmitted on the network.
The SMI specifies the use of the basic encoding rules of ASN.1 [8], subject to the additional requirements imposed by the SNMP.
Section 5 contains the specification of all object types contained in this MIB module. The object types are defined using the conventions defined in the SMI, as amended by the extensions specified in [9,10].
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 one of a set of MIBs designed for complementary use. At this writing, the set comprises:
Character MIB
PPP MIB
RS-232-like MIB
Parallel-printer-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 following diagram shows two possible "MIB stacks", each using the RS-232-like MIB.
.-----------------.
.-----------------. | Standard MIB |
| Telnet MIB | | Interface Group |
|-----------------| |-----------------|
| Character MIB | | PPP MIB |
|-----------------| |-----------------|
| RS-232-like MIB | | RS-232-like MIB |
`-----------------' `-----------------'
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 covered by the Interface group). 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.
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 comprises one base object and two tables, detailed in the following sections. The tables contain objects for ports and sessions.
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.
RFC1316-MIB DEFINITIONS ::= BEGIN
IMPORTS
Counter, TimeTicks, Gauge
FROM RFC1155-SMI
DisplayString
FROM RFC1213-MIB
OBJECT-TYPE
FROM RFC-1212;
-- this is the MIB module for character stream devices
char OBJECT IDENTIFIER ::= { mib-2 19 }
-- Textual Conventions
AutonomousType ::= OBJECT IDENTIFIER
-- The object identifier is an independently extensible type
-- identification value. It may, for example indicate a
-- particular sub-tree with further MIB definitions, or
-- define something like a protocol type or type of
-- hardware.
InstancePointer ::= OBJECT IDENTIFIER
-- The object identifier is a pointer to a specific instance
-- of a MIB object in this agent's implemented MIB. By
-- convention, it is the first object in the conceptual row
-- for the instance.
-- the generic Character group
-- Implementation of this group is mandatory for all
-- systems that offer character ports
charNumber OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The number of entries in charPortTable, regardless
of their current state."
::= { char 1 }
-- the Character Port table
charPortTable OBJECT-TYPE
SYNTAX SEQUENCE OF CharPortEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"A list of port entries. The number of entries is
given by the value of charNumber."
::= { char 2 }
charPortEntry OBJECT-TYPE
SYNTAX CharPortEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"Status and parameter values for a character port."
INDEX { charPortIndex }
::= { charPortTable 1 }
CharPortEntry ::=
SEQUENCE {
charPortIndex
INTEGER,
charPortName
DisplayString,
charPortType
INTEGER,
charPortHardware
AutonomousType,
charPortReset
INTEGER,
charPortAdminStatus
INTEGER,
charPortOperStatus
INTEGER,
charPortLastChange
TimeTicks,
charPortInFlowType
INTEGER,
charPortOutFlowType
INTEGER,
charPortInFlowState
INTEGER,
charPortOutFlowState
INTEGER,
charPortInCharacters
Counter,
charPortOutCharacters
Counter,
charPortAdminOrigin
INTEGER,
charPortSessionMaximum
INTEGER,
charPortSessionNumber
Gauge,
charPortSessionIndex
INTEGER
}
charPortIndex OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"A unique value for each character port. Its value
ranges between 1 and the value of charNumber. By
convention and if possible, hardware port numbers
come first, with a simple, direct mapping. The
value for each port must remain constant at least
from one re-initialization of the network management
agent to the next."
::= { charPortEntry 1 }
charPortName OBJECT-TYPE
SYNTAX DisplayString (SIZE (0..32))
ACCESS read-write
STATUS mandatory
DESCRIPTION
"An administratively assigned name for the port,
typically with some local significance."
::= { charPortEntry 2 }
charPortType OBJECT-TYPE
SYNTAX INTEGER { physical(1), virtual(2) }
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The port's type, 'physical' if the port represents
an external hardware connector, 'virtual' if it does
not."
::= { charPortEntry 3 }
charPortHardware OBJECT-TYPE
SYNTAX AutonomousType
ACCESS read-only
STATUS mandatory
DESCRIPTION
"A reference to hardware MIB definitions specific to
a physical port's external connector. For example,
if the connector is RS-232, then the value of this
object refers to a MIB sub-tree defining objects
specific to RS-232. If an agent is not configured
to have such values, the agent returns the object
identifier:
nullHardware OBJECT IDENTIFIER ::= { 0 0 }
"
::= { charPortEntry 4 }
charPortReset OBJECT-TYPE
SYNTAX INTEGER { ready(1), execute(2) }
ACCESS read-write
STATUS mandatory
DESCRIPTION
"A control to force the port into a clean, initial
state, both hardware and software, disconnecting all
the port's existing sessions. In response to a
get-request or get-next-request, the agent always
returns 'ready' as the value. Setting the value to
'execute' causes a reset."
::= { charPortEntry 5 }
charPortAdminStatus OBJECT-TYPE
SYNTAX INTEGER { enabled(1), disabled(2), off(3),
maintenance(4) }
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The port's desired state, independent of flow control. 'enabled' indicates that the port is allowed to pass characters and form new sessions. 'disabled' indicates that the port is allowed to pass characters but not form new sessions. 'off' indicates that the port is not allowed to pass characters or have any sessions. 'maintenance' indicates a maintenance mode, exclusive of normal operation, such as running a test."
::= { charPortEntry 6 }
charPortOperStatus OBJECT-TYPE
SYNTAX INTEGER { up(1), down(2),
maintenance(3), absent(4), active(5) }
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The port's actual, operational state, independent
of flow control. 'up' indicates able to function
normally. 'down' indicates inability to function
for administrative or operational reasons.
'maintenance' indicates a maintenance mode,
exclusive of normal operation, such as running a
test. 'absent' indicates that port hardware is not
present. 'active' indicates up with a user present
(e.g. logged in)."
::= { charPortEntry 7 }
charPortLastChange OBJECT-TYPE
SYNTAX TimeTicks
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The value of sysUpTime at the time the port entered
its current operational state. If the current state
was entered prior to the last reinitialization of
the local network management subsystem, then this
object contains a zero value."
::= { charPortEntry 8 }
charPortInFlowType OBJECT-TYPE
SYNTAX INTEGER { none(1), xonXoff(2), hardware(3),
ctsRts(4), dsrDtr(5) }
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The port's type of input flow control. 'none'
indicates no flow control at this level or below.
'xonXoff' indicates software flow control by recognizing XON and XOFF characters. 'hardware' indicates flow control delegated to the lower level, for example a parallel port.
'ctsRts' and 'dsrDtr' are specific to RS-232-like ports. Although not architecturally pure, they are included here for simplicity's sake."
::= { charPortEntry 9 }
charPortOutFlowType OBJECT-TYPE
SYNTAX INTEGER { none(1), xonXoff(2), hardware(3),
ctsRts(4), dsrDtr(5) }
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The port's type of output flow control. 'none'
indicates no flow control at this level or below.
'xonXoff' indicates software flow control by
recognizing XON and XOFF characters. 'hardware'
indicates flow control delegated to the lower level,
for example a parallel port.
'ctsRts' and 'dsrDtr' are specific to RS-232-like ports. Although not architecturally pure, they are included here for simplicy's sake."
::= { charPortEntry 10 }
charPortInFlowState OBJECT-TYPE
SYNTAX INTEGER { none(1), unknown(2), stop(3), go(4) }
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The current operational state of input flow control
on the port. 'none' indicates not applicable.
'unknown' indicates this level does not know.
'stop' indicates flow not allowed. 'go' indicates
flow allowed."
::= { charPortEntry 11 }
charPortOutFlowState OBJECT-TYPE
SYNTAX INTEGER { none(1), unknown(2), stop(3), go(4) }
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The current operational state of output flow
control on the port. 'none' indicates not
applicable. 'unknown' indicates this level does not
know. 'stop' indicates flow not allowed. 'go' indicates flow allowed."
::= { charPortEntry 12 }
charPortInCharacters OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"Total number of characters detected as input from
the port since system re-initialization and while
the port operational state was 'up', 'active', or
'maintenance', including, for example, framing, flow
control (i.e. XON and XOFF), each occurrence of a
BREAK condition, locally-processed input, and input
sent to all sessions."
::= { charPortEntry 13 }
charPortOutCharacters OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"Total number of characters detected as output to
the port since system re-initialization and while
the port operational state was 'up', 'active', or
'maintenance', including, for example, framing, flow
control (i.e. XON and XOFF), each occurrence of a
BREAK condition, locally-created output, and output
received from all sessions."
::= { charPortEntry 14 }
charPortAdminOrigin OBJECT-TYPE
SYNTAX INTEGER { dynamic(1), network(2), local(3),
none(4) }
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The administratively allowed origin for
establishing session on the port. 'dynamic' allows
'network' or 'local' session establishment. 'none'
disallows session establishment."
::= { charPortEntry 15 }
charPortSessionMaximum OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-write
STATUS mandatory
DESCRIPTION
"The maximum number of concurrent sessions allowed
on the port. A value of -1 indicates no maximum.
Setting the maximum to less than the current number
of sessions has unspecified results."
::= { charPortEntry 16 }
charPortSessionNumber OBJECT-TYPE
SYNTAX Gauge
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The number of open sessions on the port that are in
the connecting, connected, or disconnecting state."
::= { charPortEntry 17 }
charPortSessionIndex OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The value of charSessIndex for the port's first or
only active session. If the port has no active
session, the agent returns the value zero."
::= { charPortEntry 18 }
-- the Character Session table
charSessTable OBJECT-TYPE
SYNTAX SEQUENCE OF CharSessEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"A list of port session entries."
::= { char 3 }
charSessEntry OBJECT-TYPE
SYNTAX CharSessEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"Status and parameter values for a character port
session."
INDEX { charSessPortIndex, charSessIndex }
::= { charSessTable 1 }
CharSessEntry ::=
SEQUENCE {
charSessPortIndex
INTEGER,
charSessIndex
INTEGER,
charSessKill
INTEGER,
charSessState
INTEGER,
charSessProtocol
AutonomousType,
charSessOperOrigin
INTEGER,
charSessInCharacters
Counter,
charSessOutCharacters
Counter,
charSessConnectionId
InstancePointer,
charSessStartTime
TimeTicks
}
charSessPortIndex OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The value of charPortIndex for the port to which
this session belongs."
::= { charSessEntry 1 }
charSessIndex OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The session index in the context of the port, a
non-zero positive integer. Session indexes within a
port need not be sequential. Session indexes may be
reused for different ports. For example, port 1 and
port 3 may both have a session 2 at the same time.
Session indexes may have any valid integer value,
with any meaning convenient to the agent
implementation."
::= { charSessEntry 2 }
charSessKill OBJECT-TYPE
SYNTAX INTEGER { ready(1), execute(2) }
ACCESS read-write
STATUS mandatory
DESCRIPTION
"A control to terminate the session. In response to
a get-request or get-next-request, the agent always
returns 'ready' as the value. Setting the value to
'execute' causes termination."
::= { charSessEntry 3 }
charSessState OBJECT-TYPE
SYNTAX INTEGER { connecting(1), connected(2),
disconnecting(3) }
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The current operational state of the session,
disregarding flow control. 'connected' indicates
that character data could flow on the network side
of session. 'connecting' indicates moving from
nonexistent toward 'connected'. 'disconnecting'
indicates moving from 'connected' or 'connecting' to
nonexistent."
::= { charSessEntry 4 }
charSessProtocol OBJECT-TYPE
SYNTAX AutonomousType
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The network protocol over which the session is
running. Other OBJECT IDENTIFIER values may be
defined elsewhere, in association with specific
protocols. However, this document assigns those of
known interest as of this writing."
::= { charSessEntry 5 }
wellKnownProtocols OBJECT IDENTIFIER ::= { char 4 }
protocolOther OBJECT IDENTIFIER ::= {wellKnownProtocols 1}
protocolTelnet OBJECT IDENTIFIER ::= {wellKnownProtocols 2}
protocolRlogin OBJECT IDENTIFIER ::= {wellKnownProtocols 3}
protocolLat OBJECT IDENTIFIER ::= {wellKnownProtocols 4}
protocolX29 OBJECT IDENTIFIER ::= {wellKnownProtocols 5}
protocolVtp OBJECT IDENTIFIER ::= {wellKnownProtocols 6}
charSessOperOrigin OBJECT-TYPE
SYNTAX INTEGER { unknown(1), network(2), local(3) }
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The session's source of establishment."
::= { charSessEntry 6 }
charSessInCharacters OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This session's subset of charPortInCharacters."
::= { charSessEntry 7 }
charSessOutCharacters OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This session's subset of charPortOutCharacters."
::= { charSessEntry 8 }
charSessConnectionId OBJECT-TYPE
SYNTAX InstancePointer
ACCESS read-only
STATUS mandatory
DESCRIPTION
"A reference to additional local MIB information.
This should be the highest available related MIB,
corresponding to charSessProtocol, such as Telnet.
For example, the value for a TCP connection (in the
absence of a Telnet MIB) is the object identifier of
tcpConnState. If an agent is not configured to have
such values, the agent returns the object
identifier:
nullConnectionId OBJECT IDENTIFIER ::= { 0 0 }
"
::= { charSessEntry 9 }
charSessStartTime OBJECT-TYPE
SYNTAX TimeTicks
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The value of sysUpTime in MIB-2 when the session
entered connecting state."
::= { charSessEntry 10 }
END
Based on several private MIBs, this document was produced by the Character MIB Working Group:
Anne Ambler, Spider
Charles Bazaar, Emulex
Christopher Bucci, Datability
Anthony Chung, Hughes LAN Systems
George Conant, Xyplex
John Cook, Chipcom
James Davin, MIT-LCS
Shawn Gallagher, DEC
Tom Grant, Xylogics
Frank Huang, Emulex
David Jordan, Emulex
Satish Joshi, SynOptics
Frank Kastenholz, Clearpoint
Ken Key, University of Tennessee
Jim Kinder, Fibercom
Rajeev Kochhar, 3Com
John LoVerso, Xylogics
Keith McCloghrie, Hughes LAN Systems
Donald Merritt, BRL
David Perkins, 3Com
Jim Reinstedler, Ungerman-Bass
Marshall Rose, PSI
Ron Strich, SSDS
Dean Throop, DG
Bill Townsend, Xylogics
Jesse Walker, DEC
David Waitzman, BBN
Bill Westfield, cisco
[1] Cerf, V., "IAB Recommendations for the Development of Internet Network Management Standards", RFC 1052, NRI, April 1988.
[2] Cerf, V., "Report of the Second Ad Hoc Network
Management Review Group", RFC 1109, NRI, August 1989.
[3] Rose M., and K. McCloghrie, "Structure and
Identification of Management Information for TCP/IP-based
internets", RFC 1155, Performance Systems International,
Hughes LAN Systems, May 1990.
[4] McCloghrie K., and M. Rose, "Management Information Base
for Network Management of TCP/IP-based internets", RFC
1156, Hughes LAN Systems, Performance Systems
International, May 1990.
[5] Case, J., Fedor, M., Schoffstall, M., and J. Davin,
"Simple Network Management Protocol", RFC 1157, SNMP
Research, Performance Systems International, Performance
Systems International, MIT Laboratory for Computer Science,
May 1990.
[6] McCloghrie K., and M. Rose, Editors, "Management
Information Base for Network Management of TCP/IP-based
internets", RFC 1213, Performance Systems International,
March 1991.
[7] Information processing systems - Open Systems
Interconnection - Specification of Abstract Syntax Notation
One (ASN.1), International Organization for
Standardization, International Standard 8824, December
1987.
[8] Information processing systems - Open Systems
Interconnection - Specification of Basic Encoding Rules for
Abstract Notation One (ASN.1), International Organization
for Standardization, International Standard 8825, December
1987.
[9] Rose, M., and K. McCloghrie, Editors, "Concise MIB
Definitions", RFC 1212, Performance Systems International,
Hughes LAN Systems, March 1991.
[10] Rose, M., Editor, "A Convention for Defining Traps for
use with the SNMP", RFC 1215, Performance Systems
International, March 1991.
Security issues are not discussed in this memo.
Bob Stewart
Xyplex, Inc.
330 Codman Hill Road
Boxborough, MA 01719
Phone: (508) 264-9900
EMail: rlstewart@eng.xyplex.com