RFC 1658

Definitions of Managed Objects for Character Stream Devices using SMIv2

๐Ÿ“… published July 1994, from ietf

Definitions of Managed Objects for Character Stream Devices using SMIv2 ๐ŸŽ€

okay bestie, the title block is basically this doc's ID card ๐Ÿชช๐Ÿ’–. It's RFC 1658, titled Definitions of Managed Objects for Character Stream Devices using SMIv2, from the Network Working Group ๐Ÿซถ. Bob Stewart (B. Stewart) wrote it at Xyplex, Inc., and it's dated July 1994 ๐Ÿ“…. It's on the Standards Track (so it's the real deal, not just vibes ๐Ÿ‘‘), and it obsoletes RFC 1316 ๐Ÿ’….

Status of This Memo ๐Ÿ“œ

this doc specifies an Internet standards track protocol for the Internet community, and it's literally asking for discussion and suggestions for improvements ๐Ÿ™. For the standardization state and status of this protocol, check the current edition of the "Internet Official Protocol Standards" (STD 1) bc that's the source of truth ๐Ÿ’…. Distribution of this memo is unlimited โœจ.

Table of Contents ๐Ÿงš

   1. Introduction ................................................    2
   2. The SNMPv2 Network Management Framework .....................    2
   2.1 Object Definitions .........................................    3
   3. Overview ....................................................    3
   3.1 Relationship to Interface MIB ..............................    4
   4. Definitions .................................................    4
   5. Acknowledgements ............................................   17
   6. References ..................................................   17
   7. Security Considerations .....................................   18
   8. Author's Address ............................................   18

1. Introduction โœจ

so this memo adds an extension to the Management Information Base (MIB) ๐Ÿง  for network management protocols in the Internet community ๐ŸŒ. Specifically, it defines objects for managing character stream devices ๐Ÿ’ป.

2. The SNMPv2 Network Management Framework ๐Ÿ’…

the SNMPv2 Network Management Framework has four major components ๐Ÿ‘‘:

  • RFC 1442 [1] defines the SMI, which is the mechanism for describing and naming objects for management ๐Ÿท๏ธ.
  • STD 17, RFC 1213 [2] defines MIB-II, the core set of managed objects for the Internet suite of protocols ๐Ÿ’–.
  • RFC 1445 [3] defines the administrative and other architectural aspects of the framework ๐Ÿ›๏ธ.
  • RFC 1448 [4] defines the protocol used for network access to managed objects ๐Ÿšช.

the Framework permits new objects to be defined for experimentation and evaluation ๐Ÿงช.

2.1. Object Definitions

objects are accessed through a virtual information store called the Management Information Base, or MIB ๐Ÿ—‚๏ธ. Objects in the MIB are defined using the subset of Abstract Syntax Notation One (ASN.1) that the SMI defines ๐Ÿค“. Each object type is named by an OBJECT IDENTIFIER, which is an administratively assigned name. The object type together with an object instance uniquely identifies one specific instantiation of the object ๐Ÿ”. For human convenience, we often use a textual string, called the descriptor, to refer to the object type ๐Ÿซถ.

3. Overview ๐Ÿฆ‹

the Character MIB applies to ports that carry a character stream, whether they're physical or virtual, serial or parallel, synchronous or asynchronous ๐Ÿ”Œ. The most common example is a hardware terminal port with an RS-232 interface. Another common hardware example is a parallel printer port, say with a Centronics interface ๐Ÿ–จ๏ธ. The concept also includes virtual terminal ports, like a software connection point for a remote console ๐Ÿ–ฅ๏ธ.

the Character MIB is mandatory for all systems that offer character stream ports ๐Ÿ’…. That includes, for example, terminal servers, general-purpose time-sharing hosts, and even stuff like a bridge with a (virtual) console port ๐ŸŒ‰. It may or may not include character ports that don't support network sessions, depending on the system's needs ๐Ÿคทโ€โ™€๏ธ.

the Character MIB's central abstraction is a port ๐Ÿ’—. Physical ports have a one-to-one correspondence with hardware ports. Virtual ports are software entities that are analogous to physical ports, but with no hardware connector ๐Ÿ‘ป.

each port supports one or more sessions ๐ŸŽ€. A session is 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 ๐Ÿ“ก.

the MIB comprises one base object and two tables, which are detailed in the following sections. The tables contain objects for ports and sessions ๐Ÿ“‹.

the MIB intentionally contains no distinction between what is often called permanent and operational or volatile data bases ๐Ÿ™ˆ. For the purposes of this MIB, handling of those distinctions is implementation specific ๐Ÿ› ๏ธ.

3.1. Relationship to Interface MIB

the Character MIB doesn't relate directly to the Interface MIB [1], since it isn't intrinsically a network interface ๐Ÿ™…โ€โ™€๏ธ. On the other hand, in most implementations where it's present, it will be above a physical sublayer interface, such as the RS-232-like [2] or Parallel-printer-like [3] MIBs ๐Ÿงฉ. Those physical interfaces are typically represented by a row in the interface table (ifTable), identified by a value of ifIndex ๐Ÿท๏ธ.

4. Definitions ๐ŸŽ€

okay, the big one: the actual MIB module ๐Ÿ‘€. It's copied exactly, character for character, because implementers rely on every single bit of it ๐Ÿ’…:

   CHARACTER-MIB DEFINITIONS ::= BEGIN

   IMPORTS
       MODULE-IDENTITY, OBJECT-TYPE, NOTIFICATION-TYPE,
       Counter32, Integer32, Gauge32, TimeTicks
           FROM SNMPv2-SMI
       AutonomousType, InstancePointer
           FROM SNMPv2-TC
       InterfaceIndex
           FROM IF-MIB
       transmission, mib-2
           FROM RFC1213-MIB
       MODULE-COMPLIANCE, OBJECT-GROUP
           FROM SNMPv2-CONF;


   char MODULE-IDENTITY
       LAST-UPDATED "9405261700Z"
       ORGANIZATION "IETF Character MIB Working Group"
       CONTACT-INFO
               "        Bob Stewart
                Postal: Xyplex, Inc.
                        295 Foster Street
                        Littleton, MA 01460

                   Tel: 508-952-4816
                   Fax: 508-952-4887

                E-mail: rlstewart@eng.xyplex.com"
       DESCRIPTION
               "The MIB module for character stream devices."
       ::= { mib-2 19 }

   PortIndex ::= TEXTUAL-CONVENTION
       DISPLAY-HINT "d"
       STATUS current
       DESCRIPTION
               "A unique value, greater than zero, for each
               character port in the managed system.  It is
               recommended that values are assigned contiguously
               starting from 1.  The value for each interface sub-
               layer must remain constant at least from one re-
               initialization of the entity's network management
               system to the next re-initialization.

               In a system where the character ports are attached
               to hardware represented by an ifIndex, it is
               conventional, but not required, to make the
               character port index equal to the corresponding
               ifIndex."
       SYNTAX Integer32


   -- Generic Character information

   charNumber OBJECT-TYPE
       SYNTAX Integer32
       MAX-ACCESS read-only
       STATUS current
       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
       MAX-ACCESS not-accessible
       STATUS current
       DESCRIPTION
           "A list of port entries.  The number of entries is
           given by the value of charNumber."
       ::= { char 2 }

   charPortEntry OBJECT-TYPE
       SYNTAX CharPortEntry
       MAX-ACCESS not-accessible
       STATUS current
       DESCRIPTION
           "Status and parameter values for a character port."
       INDEX { charPortIndex }
       ::= { charPortTable 1 }

   CharPortEntry ::=
       SEQUENCE {
           charPortIndex
               PortIndex,
           charPortName
               DisplayString,
           charPortType
               INTEGER,
           charPortHardware
               AutonomousType,
           charPortReset
               INTEGER,
           charPortAdminStatus
               INTEGER,
           charPortOperStatus
               INTEGER,
           charPortLastChange
               TimeTicks,
           charPortInFlowType
               INTEGER,
           charPortOutFlowType
               INTEGER,
           charPortInFlowState
               INTEGER,
           charPortOutFlowState
               INTEGER,
           charPortInCharacters
               Counter32,
           charPortOutCharacters
               Counter32,
           charPortAdminOrigin
               INTEGER,
           charPortSessionMaximum
               INTEGER,
           charPortSessionNumber
               Gauge32,
           charPortSessionIndex
               INTEGER,
           charPortInFlowTypes

               OCTET STRING,
           charPortOutFlowTypes
               OCTET STRING,
           charPortLowerIfIndex
               InterfaceIndex
       }

   charPortIndex OBJECT-TYPE
       SYNTAX PortIndex
       MAX-ACCESS read-only
       STATUS current
       DESCRIPTION
           "A unique value for each character port, perhaps
           corresponding to the same value of ifIndex when the
           character port is associated with a hardware port
           represented by an ifIndex."
       ::= { charPortEntry 1 }

   charPortName OBJECT-TYPE
       SYNTAX DisplayString (SIZE (0..32))
       MAX-ACCESS read-write
       STATUS current
       DESCRIPTION
           "An administratively assigned name for the port,
           typically with some local significance."
       ::= { charPortEntry 2 }

   charPortType OBJECT-TYPE
       SYNTAX INTEGER { physical(1), virtual(2) }
       MAX-ACCESS read-only
       STATUS current
       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
       MAX-ACCESS read-only
       STATUS current
       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) }
       MAX-ACCESS read-write
       STATUS current
       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 }

the next part picks up right where charPortReset leaves off, so the rest of the port table is coming ๐Ÿ‘€๐Ÿงš

Okay bestie, the port states are where things get spicy ๐ŸŒถ๏ธ Here's how the admin and operational status objects work, plus the flow control stuff โœจ

   charPortAdminStatus OBJECT-TYPE
       SYNTAX INTEGER { enabled(1), disabled(2), off(3),
                        maintenance(4) }
       MAX-ACCESS read-write
       STATUS current
       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.

           'enabled' corresponds to ifAdminStatus 'up'.
           'disabled' and 'off' correspond to ifAdminStatus
           'down'.  'maintenance' corresponds to ifAdminStatus
           'test'."
       ::= { charPortEntry 6 }

   charPortOperStatus OBJECT-TYPE
       SYNTAX INTEGER { up(1), down(2),
                        maintenance(3), absent(4), active(5) }
       MAX-ACCESS read-only
       STATUS current
       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).

           'up' and 'active' correspond to ifOperStatus 'up'.
           'down' and 'absent' correspond to ifOperStatus
           'down'.  'maintenance' corresponds to ifOperStatus
           'test'."
       ::= { charPortEntry 7 }

   charPortLastChange OBJECT-TYPE
       SYNTAX TimeTicks
       MAX-ACCESS read-only
       STATUS current
       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 }

So charPortAdminStatus is the port's wish list ๐Ÿ’…, and it's independent of flow control. enabled means the port can pass characters AND make new sessions, disabled lets it pass characters but no new sessions, and off means no characters and no sessions at all ๐Ÿ™…โ€โ™€๏ธ. Then maintenance is its own mode, separate from normal operation, like when you're running a test ๐Ÿงช. It lines up with ifAdminStatus like this: enabled is up, disabled and off are down, and maintenance is test ๐Ÿฆ‹

charPortOperStatus is the real vibe, the actual state, also independent of flow control โœจ up means it's able to function normally ๐ŸŒธ down means it can't, for admin or operational reasons. absent means the port hardware isn't even there ๐Ÿ‘ป and active is up with a user present, like someone's logged in ๐Ÿซถ. Mapping-wise, up and active both match ifOperStatus up, down and absent match down, and maintenance matches test ๐ŸŽ€

charPortLastChange is giving timestamp energy โฐ It's the sysUpTime from when the port entered its current operational state. If that happened before the local network management subsystem last reinitialized, the object just says zero ๐Ÿ™ˆ


   -- charPortInFlowType is deprecated in favor of
   -- charPortInFlowTypes

   charPortInFlowType OBJECT-TYPE
       SYNTAX INTEGER { none(1), xonXoff(2), hardware(3),
                        ctsRts(4), dsrDtr(5) }
       MAX-ACCESS read-write
       STATUS deprecated
       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 is deprecated in favor of
   -- charPortOutFlowTypes

   charPortOutFlowType OBJECT-TYPE
       SYNTAX INTEGER { none(1), xonXoff(2), hardware(3),
                        ctsRts(4), dsrDtr(5) }
       MAX-ACCESS read-write
       STATUS deprecated
       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 }

Now the old flow control types ๐Ÿ™ƒ charPortInFlowType and charPortOutFlowType are both deprecated, so the move is to use charPortInFlowTypes and charPortOutFlowTypes instead ๐Ÿ’€ The options are none, xonXoff (software flow control by recognizing XON and XOFF characters), hardware (delegated to the lower level, like a parallel port), ctsRts, and dsrDtr ๐Ÿ”Œ The last two are for RS-232-like ports. They're not architecturally pure, but they got included for simplicity's sake, which is honestly relatable ๐Ÿฅน

   charPortInFlowState OBJECT-TYPE
       SYNTAX INTEGER { none(1), unknown(2), stop(3), go(4) }
       MAX-ACCESS read-only
       STATUS current
       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) }
       MAX-ACCESS read-only
       STATUS current
       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 }

charPortInFlowState and charPortOutFlowState show what flow control is doing right now ๐Ÿšฆ none means not applicable, unknown means this level just doesn't know, stop means flow isn't allowed, and go means flow is allowed. Same vibes for both directions, so no drama there ๐Ÿ’–

   charPortInCharacters OBJECT-TYPE
       SYNTAX Counter32
       MAX-ACCESS read-only
       STATUS current
       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 Counter32
       MAX-ACCESS read-only
       STATUS current
       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 }

The character counters are the tea โ˜• charPortInCharacters counts input from the port since system re-initialization, but only while the operational state is up, active, or maintenance. It counts everything, like framing, XON and XOFF, every BREAK, locally processed input, and input sent to all sessions ๐Ÿ“Š charPortOutCharacters is the mirror image for output ๐Ÿชž Both are Counter32, so they're giving wrap-around vibes too ๐ŸŒ€

   charPortAdminOrigin OBJECT-TYPE
       SYNTAX INTEGER { dynamic(1), network(2), local(3),
                        none(4) }
       MAX-ACCESS read-write
       STATUS current
       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 (-1..2147483647)
       MAX-ACCESS read-write
       STATUS current
       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 Gauge32
       MAX-ACCESS read-only
       STATUS current
       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 (0..2147483647)
       MAX-ACCESS read-only
       STATUS current
       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 }

charPortAdminOrigin decides who's allowed to start a session on the port ๐Ÿ”‘ dynamic lets network or local sessions in, and none shuts the door completely ๐Ÿšช Then charPortSessionMaximum is the bouncer's headcount ๐Ÿ’ƒ -1 means no maximum, and if you set the max below the number of sessions that are already open, the results are unspecified, so please don't do that ๐Ÿ™

charPortSessionNumber counts open sessions in the connecting, connected, or disconnecting state ๐Ÿงฎ charPortSessionIndex points at the charSessIndex of the port's first or only active session. If there isn't one, the agent returns zero 0๏ธโƒฃ

   charPortInFlowTypes OBJECT-TYPE
       SYNTAX OCTET STRING (SIZE (1))
       MAX-ACCESS read-write
       STATUS current
       DESCRIPTION
           "The port's types of input flow control at the
           software level.  Hardware-level flow control is
           independently controlled by the appropriate
           hardware-level MIB.

           A value of zero indicates no flow control.
           Depending on the specific implementation, any or
           all combinations of flow control may be chosen by
           adding the values:

           128  xonXoff, recognizing XON and XOFF characters
           64   enqHost, ENQ/ACK to allow input to host
           32   enqTerm, ACK to allow output to port
           "
       ::= { charPortEntry 19 }

   charPortOutFlowTypes OBJECT-TYPE
       SYNTAX OCTET STRING (SIZE (1))
       MAX-ACCESS read-write
       STATUS current
       DESCRIPTION
           "The port's types of output flow control at the
           software level.  Hardware-level flow control is
           independently controlled by the appropriate
           hardware-level MIB.

           A value of zero indicates no flow control.
           Depending on the specific implementation, any or
           all combinations of flow control may be chosen by
           adding the values:

           128  xonXoff, recognizing XON and XOFF characters
           64   enqHost, ENQ/ACK to allow input to host
           32   enqTerm, ACK to allow output to port
           "
       ::= { charPortEntry 20 }

Okay, this is the software-level flow control menu ๐Ÿฑ These are the software ones only, since hardware-level flow control is handled by its own hardware MIB ๐Ÿ”ง Zero means no flow control. Otherwise you can mix and match by adding the values together โž• 128 is xonXoff, 64 is enqHost (ENQ/ACK to allow input to host), and 32 is enqTerm (ACK to allow output to port). Math, but make it cute ๐Ÿงฎ๐Ÿ’– charPortOutFlowTypes is the same thing for output ๐ŸŽ€

   charPortLowerIfIndex OBJECT-TYPE
       SYNTAX InterfaceIndex
       MAX-ACCESS read-only
       STATUS current
       DESCRIPTION
           "The ifIndex value of the lower level hardware supporting
           this character port, zero if none."
       ::= { charPortEntry 21 }


   -- the Character Session table

   charSessTable OBJECT-TYPE
       SYNTAX SEQUENCE OF CharSessEntry
       MAX-ACCESS not-accessible
       STATUS current
       DESCRIPTION
           "A list of port session entries."
       ::= { char 3 }

   charSessEntry OBJECT-TYPE
       SYNTAX CharSessEntry
       MAX-ACCESS not-accessible
       STATUS current
       DESCRIPTION
           "Status and parameter values for a character port
           session."
       INDEX { charSessPortIndex, charSessIndex }
       ::= { charSessTable 1 }

   CharSessEntry ::=
       SEQUENCE {
           charSessPortIndex
               PortIndex,
           charSessIndex

               INTEGER,
           charSessKill
               INTEGER,
           charSessState
               INTEGER,
           charSessProtocol
               AutonomousType,
           charSessOperOrigin
               INTEGER,
           charSessInCharacters
               Counter32,
           charSessOutCharacters
               Counter32,
           charSessConnectionId
               InstancePointer,
           charSessStartTime
               TimeTicks
       }

   charSessPortIndex OBJECT-TYPE
       SYNTAX PortIndex
       MAX-ACCESS read-only
       STATUS current
       DESCRIPTION
           "The value of charPortIndex for the port to which
           this session belongs."
       ::= { charSessEntry 1 }

   charSessIndex OBJECT-TYPE
       SYNTAX INTEGER (1..2147483647)
       MAX-ACCESS read-only
       STATUS current
       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) }
       MAX-ACCESS read-write
       STATUS current
       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 }

charPortLowerIfIndex is the link back down to the hardware ๐Ÿ”— It holds the ifIndex of the lower-level hardware that supports this character port, and it's zero if there isn't any ๐Ÿงฑ

Now we're in the Character Session table ๐ŸŽ€ charSessTable is just the list of port session entries ๐Ÿ“‹ Each row is a charSessEntry, which holds the status and parameters for one character port session. Rows are indexed by charSessPortIndex and charSessIndex together, which is very much a "you need both to find your person" situation ๐Ÿ’‘

charSessPortIndex is the charPortIndex of the port the session belongs to ๐Ÿ” charSessIndex is the session number within that port. It's a non-zero positive integer, and the numbers don't have to be sequential. They can get reused across different ports, so port 1 and port 3 can both have a session 2 at the same time ๐Ÿ‘ฏ The agent is free to give them any valid integer value, with whatever meaning works for its implementation ๐Ÿงš

charSessKill is the big red button ๐Ÿ”ด It's a control for terminating the session. If you ask for it with a get-request or get-next-request, you'll always get ready back. Setting it to execute is what actually causes the termination ๐Ÿ’€

Okay the MIB definitions are where it gets really spicy ๐ŸŒธ here's the rest of the module, no cap it's giving precision ๐Ÿ’…

   charSessState OBJECT-TYPE
       SYNTAX INTEGER { connecting(1), connected(2),
                        disconnecting(3) }
       MAX-ACCESS read-only
       STATUS current
       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
       MAX-ACCESS read-only
       STATUS current
       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) }
       MAX-ACCESS read-only
       STATUS current
       DESCRIPTION

           "The session's source of establishment."
       ::= { charSessEntry 6 }

   charSessInCharacters OBJECT-TYPE
       SYNTAX Counter32
       MAX-ACCESS read-only
       STATUS current
       DESCRIPTION
           "This session's subset of charPortInCharacters."
       ::= { charSessEntry 7 }

   charSessOutCharacters OBJECT-TYPE
       SYNTAX Counter32
       MAX-ACCESS read-only
       STATUS current
       DESCRIPTION
           "This session's subset of charPortOutCharacters."
       ::= { charSessEntry 8 }

   charSessConnectionId OBJECT-TYPE
       SYNTAX InstancePointer
       MAX-ACCESS read-only
       STATUS current
       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
       MAX-ACCESS read-only
       STATUS current
       DESCRIPTION
           "The value of sysUpTime in MIB-2 when the session
           entered connecting state."
       ::= { charSessEntry 10 }

   -- conformance information

   charConformance OBJECT IDENTIFIER ::= { char 5 }

   charGroups      OBJECT IDENTIFIER ::= { charConformance 1 }
   charCompliances OBJECT IDENTIFIER ::= { charConformance 2 }


   -- compliance statements

   charCompliance MODULE-COMPLIANCE
       STATUS  current
       DESCRIPTION
               "The compliance statement for SNMPv2 entities
               which have Character hardware interfaces."

       MODULE  -- this module
           MANDATORY-GROUPS { charGroup }
       ::= { charCompliances 1 }


   -- units of conformance

   charGroup    OBJECT-GROUP
       OBJECTS { charNumber, charPortIndex, charPortName,
                 charPortType, charPortHardware, charPortReset,
                 charPortAdminStatus, charPortOperStatus,
                 charPortLastChange,
                 charPortInFlowState, charPortOutFlowState,
                 charPortAdminOrigin, charPortSessionMaximum,
                 charPortInFlowTypes, charPortOutFlowTypes,
                 charPortInCharacters, charPortOutCharacters,
                 charPortSessionNumber, charPortSessionIndex,
                 charPortLowerIfIndex,
                 charSessPortIndex, charSessIndex,
                 charSessKill, charSessState,
                 charSessProtocol, charSessOperOrigin,
                 charSessInCharacters, charSessOutCharacters,
                 charSessConnectionId, charSessStartTime }
       STATUS  current
       DESCRIPTION
               "A collection of objects providing information
                applicable to all Character interfaces."
       ::= { charGroups 1 }

   END

5. Acknowledgements โœจ

Big shoutout to the IETF Character MIB Working Group ๐Ÿซถ they're the ones who produced this memo, bestie, so iconic.

6. References ๐Ÿ“š

  • [1] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Structure of Management Information for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1442, SNMP Research,Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993.
  • [2] McCloghrie, K., and M. Rose, Editors, "Management Information Base for Network Management of TCP/IP-based internets: MIB-II", STD 17, RFC 1213, Hughes LAN Systems, Performance Systems International, March 1991.
  • [3] Galvin, J., and K. McCloghrie, "Administrative Model for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1445, Trusted Information Systems, Hughes LAN Systems, April 1993.
  • [4] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol Operations for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1448, SNMP Research,Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993.
  • [5] McCloghrie, K., and F. Kastenholz, "Evolution of the Interfaces Group of MIB-II", RFC 1573, Hughes LAN Systems, FTP Software, January 1994.
  • [6] Stewart, B., "Definitions of Managed Objects for RS-232-like Hardware Devices using SMIv2", RFC 1659, Xyplex, Inc., July 1994.
  • [7] Stewart, B., "Definitions of Managed Objects for Parallel-printer-like Hardware Devices using SMIv2", RFC 1660, Xyplex, Inc., July 1994.

7. Security Considerations ๐Ÿ”’

Security issues are not discussed in this memo, so go in with your eyes open ๐Ÿ‘€

8. Author's Address ๐Ÿ’Œ

Bob Stewart from Xyplex, Inc. wrote this one, and here's how to reach him ๐Ÿฆ‹

   Bob Stewart
   Xyplex, Inc.
   295 Foster Street
   Littleton, MA 01460

   Phone: 508-952-4816
   Fax: 508-952-4887
   EMail: rlstewart@eng.xyplex.com
๐Ÿ“ฆ where this page comes from