RS-232-MIB

MIB Reference — IPNetwork Monitor

All MIBsRS-232-MIB

Organization: IETF Character MIB Working Group

Last Updated: 1994-05-26

Category: Hardware and Environment, Network Interfaces

Description:

Defines managed objects for RS-232-like hardware character port interfaces, including asynchronous and synchronous serial ports.

Imported Objects

From IF-MIB

InterfaceIndex

From RFC1213-MIB

transmission

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-SMI

Counter32
Integer32
MODULE-IDENTITY
NOTIFICATION-TYPE
OBJECT-TYPE

What Is RS-232-MIB?

RS-232-MIB is a vendor-neutral IETF standards-track MIB module defining managed objects for RS-232-like hardware character ports, covering both asynchronous and synchronous serial interfaces found on network and telecom equipment. It exposes port configuration such as baud rate, parity, and signal state, plus operational status of the physical serial connection (e.g., DTR/DCD signal states). Its monitoring value is primarily hardware status of the serial port itself: whether the port is correctly configured and whether its control signals indicate an active, connected peer device. It is commonly used alongside the RS-232-like port's associated Async/Sync port MIBs (rs232AsyncPortTable, rs232SyncPortTable conventions) that build on this base module. It is deployed on console/management ports of routers, switches, modems, and terminal servers that provide serial console or dial-up access. Engineers implementing or auditing this functionality typically reference the RS-232-MIB RFC/standard documentation for the authoritative specification.

IPNetwork Monitor allows you to monitor SNMP objects defined in RS-232-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

What Can Be Monitored

  • serial port configuration (baud rate, parity)
  • control signal states (DTR/DCD/DSR)
  • port connection status

Supported Devices

  • vendor-neutral, standards-based MIB, not tied to a specific manufacturer
  • routers/switches/terminal servers with serial console or modem ports

Monitoring Examples

Because sample_objects were not extracted for this module, specific instance names cannot be cited, but per RFC 1659 conventions an administrator would poll rs232PortTable entries for signal state objects (e.g., DTR, DCD, DSR) to confirm a console cable or modem connection is active. A serial port control signal unexpectedly dropping to 'off' would indicate a disconnected cable or a failed terminal server port, useful for diagnosing lost out-of-band management access.

OIDs
OID symbolicOID numericTypeAccessDescription
rs2321.3.6.1.2.1.10.33The MIB module for RS-232-like hardware devices.
I32 rs232Number1.3.6.1.2.1.10.33.1Integer32read-onlyThe number of ports (regardless of their current state) in the RS-232-like general port table.
rs232PortTable1.3.6.1.2.1.10.33.2not-accessibleA list of port entries. The number of entries is given by the value of rs232Number.
rs232PortEntry1.3.6.1.2.1.10.33.2.1not-accessibleStatus and parameter values for a port.
NUM rs232PortIndex1.3.6.1.2.1.10.33.2.1.1InterfaceIndexread-onlyThe value of ifIndex for the port. By convention and if possible, hardware port numbers map directly to external connectors. The value for each port must remain constant at least from one re-initialization of the network management agent to the next.
INT rs232PortType1.3.6.1.2.1.10.33.2.1.2INTEGERread-onlyThe port's hardware type.
I32 rs232PortInSigNumber1.3.6.1.2.1.10.33.2.1.3Integer32read-onlyThe number of input signals for the port in the input signal table (rs232PortInSigTable). The table contains entries only for those signals the software can detect and that are useful to observe.
I32 rs232PortOutSigNumber1.3.6.1.2.1.10.33.2.1.4Integer32read-onlyThe number of output signals for the port in the output signal table (rs232PortOutSigTable). The table contains entries only for those signals the software can assert and that are useful to observe.
I32 rs232PortInSpeed1.3.6.1.2.1.10.33.2.1.5Integer32read-writeThe port's input speed in bits per second. Note that non-standard values, such as 9612, are probably not allowed on most implementations.
I32 rs232PortOutSpeed1.3.6.1.2.1.10.33.2.1.6Integer32read-writeThe port's output speed in bits per second. Note that non-standard values, such as 9612, are probably not allowed on most implementations.
INT rs232PortInFlowType1.3.6.1.2.1.10.33.2.1.7INTEGERread-writeThe port's type of input flow control. 'none' indicates no flow control at this level. 'ctsRts' and 'dsrDtr' indicate use of the indicated hardware signals.
INT rs232PortOutFlowType1.3.6.1.2.1.10.33.2.1.8INTEGERread-writeThe port's type of output flow control. 'none' indicates no flow control at this level. 'ctsRts' and 'dsrDtr' indicate use of the indicated hardware signals.
rs232AsyncPortTable1.3.6.1.2.1.10.33.3not-accessibleA list of asynchronous port entries. Entries need not exist for synchronous ports.
rs232AsyncPortEntry1.3.6.1.2.1.10.33.3.1not-accessibleStatus and parameter values for an asynchronous port.
NUM rs232AsyncPortIndex1.3.6.1.2.1.10.33.3.1.1InterfaceIndexread-onlyA unique value for each port. Its value is the same as rs232PortIndex for the port.
INT rs232AsyncPortBits1.3.6.1.2.1.10.33.3.1.2INTEGERread-writeThe port's number of bits in a character.
INT rs232AsyncPortStopBits1.3.6.1.2.1.10.33.3.1.3INTEGERread-writeThe port's number of stop bits.
INT rs232AsyncPortParity1.3.6.1.2.1.10.33.3.1.4INTEGERread-writeThe port's sense of a character parity bit.
INT rs232AsyncPortAutobaud1.3.6.1.2.1.10.33.3.1.5INTEGERread-writeA control for the port's ability to automatically sense input speed. When rs232PortAutoBaud is 'enabled', a port may autobaud to values different from the set values for speed, parity, and character size. As a result a network management system may temporarily observe values different from what was previously set.
C32 rs232AsyncPortParityErrs1.3.6.1.2.1.10.33.3.1.6Counter32read-onlyTotal number of characters with a parity error, input from the port since system re-initialization and while the port state was 'up' or 'test'.
C32 rs232AsyncPortFramingErrs1.3.6.1.2.1.10.33.3.1.7Counter32read-onlyTotal number of characters with a framing error, input from the port since system re-initialization and while the port state was 'up' or 'test'.
C32 rs232AsyncPortOverrunErrs1.3.6.1.2.1.10.33.3.1.8Counter32read-onlyTotal number of characters with an overrun error, input from the port since system re-initialization and while the port state was 'up' or 'test'.
rs232SyncPortTable1.3.6.1.2.1.10.33.4not-accessibleA list of asynchronous port entries. Entries need not exist for synchronous ports.
rs232SyncPortEntry1.3.6.1.2.1.10.33.4.1not-accessibleStatus and parameter values for a synchronous port.
NUM rs232SyncPortIndex1.3.6.1.2.1.10.33.4.1.1InterfaceIndexread-onlyA unique value for each port. Its value is the same as rs232PortIndex for the port.
INT rs232SyncPortClockSource1.3.6.1.2.1.10.33.4.1.2INTEGERread-writeSource of the port's bit rate clock. 'split' means the tranmit clock is internal and the receive clock is external.
C32 rs232SyncPortFrameCheckErrs1.3.6.1.2.1.10.33.4.1.3Counter32read-onlyTotal number of frames with an invalid frame check sequence, input from the port since system re-initialization and while the port state was 'up' or 'test'.
C32 rs232SyncPortTransmitUnderrunErrs1.3.6.1.2.1.10.33.4.1.4Counter32read-onlyTotal number of frames that failed to be transmitted on the port since system re-initialization and while the port state was 'up' or 'test' because data was not available to the transmitter in time.
C32 rs232SyncPortReceiveOverrunErrs1.3.6.1.2.1.10.33.4.1.5Counter32read-onlyTotal number of frames that failed to be received on the port since system re-initialization and while the port state was 'up' or 'test' because the receiver did not accept the data in time.
C32 rs232SyncPortInterruptedFrames1.3.6.1.2.1.10.33.4.1.6Counter32read-onlyTotal number of frames that failed to be received or transmitted on the port due to loss of modem signals since system re-initialization and while the port state was 'up' or 'test'.
C32 rs232SyncPortAbortedFrames1.3.6.1.2.1.10.33.4.1.7Counter32read-onlyNumber of frames aborted on the port due to receiving an abort sequence since system re-initialization and while the port state was 'up' or 'test'.
INT rs232SyncPortRole1.3.6.1.2.1.10.33.4.1.8INTEGERread-writeThe role the device is playing that is using this port. dte means the device is performing the role of data terminal equipment dce means the device is performing the role of data circuit-terminating equipment.
INT rs232SyncPortEncoding1.3.6.1.2.1.10.33.4.1.9INTEGERread-writeThe bit stream encoding technique that is in effect for this port. nrz for Non-Return to Zero encoding nrzi for Non-Return to Zero Inverted encoding.
INT rs232SyncPortRTSControl1.3.6.1.2.1.10.33.4.1.10INTEGERread-writeThe method used to control the Request To Send (RTS) signal. controlled when the DTE is asserts RTS each time data needs to be transmitted and drops RTS at some point after data transmission begins. If rs232SyncPortRole is 'dte', the RTS is an output signal. The device will issue a RTS and wait for a CTS from the DCE before starting to transmit. If rs232SyncPortRole is 'dce', the RTS is an input signal. The device will issue a CTS only after having received RTS and waiting the rs232SyncPortRTSCTSDelay interval. constant when the DTE constantly asserts RTS.
I32 rs232SyncPortRTSCTSDelay1.3.6.1.2.1.10.33.4.1.11Integer32read-writeThe interval (in milliseconds) that the DCE must wait after it sees RTS asserted before asserting CTS. This object exists in support of older synchronous devices that cannot recognize CTS within a certain interval after it asserts RTS.
INT rs232SyncPortMode1.3.6.1.2.1.10.33.4.1.12INTEGERread-writeThe mode of operation of the port with respect to the direction and simultaneity of data transfer. fdx when frames on the data link can be transmitted and received at the same time hdx when frames can either be received from the data link or transmitted onto the data link but not at the same time. simplex-receive when frames can only be received on this data link. simplex-send when frames can only be sent on this data link.
INT rs232SyncPortIdlePattern1.3.6.1.2.1.10.33.4.1.13INTEGERread-writeThe bit pattern used to indicate an idle line.
I32 rs232SyncPortMinFlags1.3.6.1.2.1.10.33.4.1.14Integer32read-writeThe minimum number of flag patterns this port needs in order to recognize the end of one frame and the start of the next. Plausible values are 1 and 2.
rs232InSigTable1.3.6.1.2.1.10.33.5not-accessibleA list of port input control signal entries implemented and visible to the software on the port, and useful to monitor.
rs232InSigEntry1.3.6.1.2.1.10.33.5.1not-accessibleInput control signal status for a hardware port.
NUM rs232InSigPortIndex1.3.6.1.2.1.10.33.5.1.1InterfaceIndexread-onlyThe value of rs232PortIndex for the port to which this entry belongs.
INT rs232InSigName1.3.6.1.2.1.10.33.5.1.2INTEGERread-onlyIdentification of a hardware signal, as follows: rts Request to Send cts Clear to Send dsr Data Set Ready dtr Data Terminal Ready ri Ring Indicator dcd Received Line Signal Detector sq Signal Quality Detector srs Data Signaling Rate Selector srts Secondary Request to Send scts Secondary Clear to Send sdcd Secondary Received Line Signal Detector
INT rs232InSigState1.3.6.1.2.1.10.33.5.1.3INTEGERread-onlyThe current signal state.
C32 rs232InSigChanges1.3.6.1.2.1.10.33.5.1.4Counter32read-onlyThe number of times the signal has changed from 'on' to 'off' or from 'off' to 'on'.
rs232OutSigTable1.3.6.1.2.1.10.33.6not-accessibleA list of port output control signal entries implemented and visible to the software on the port, and useful to monitor.
rs232OutSigEntry1.3.6.1.2.1.10.33.6.1not-accessibleOutput control signal status for a hardware port.
NUM rs232OutSigPortIndex1.3.6.1.2.1.10.33.6.1.1InterfaceIndexread-onlyThe value of rs232PortIndex for the port to which this entry belongs.
INT rs232OutSigName1.3.6.1.2.1.10.33.6.1.2INTEGERread-onlyIdentification of a hardware signal, as follows: rts Request to Send cts Clear to Send dsr Data Set Ready dtr Data Terminal Ready ri Ring Indicator dcd Received Line Signal Detector sq Signal Quality Detector srs Data Signaling Rate Selector srts Secondary Request to Send scts Secondary Clear to Send sdcd Secondary Received Line Signal Detector
INT rs232OutSigState1.3.6.1.2.1.10.33.6.1.3INTEGERread-onlyThe current signal state.
C32 rs232OutSigChanges1.3.6.1.2.1.10.33.6.1.4Counter32read-onlyThe number of times the signal has changed from 'on' to 'off' or from 'off' to 'on'.
rs232Conformance1.3.6.1.2.1.10.33.7
rs232Groups1.3.6.1.2.1.10.33.7.1
rs232Group1.3.6.1.2.1.10.33.7.1.1A collection of objects providing information applicable to all RS-232-like interfaces.
rs232AsyncGroup1.3.6.1.2.1.10.33.7.1.2A collection of objects providing information applicable to asynchronous RS-232-like interfaces.
rs232SyncGroup1.3.6.1.2.1.10.33.7.1.3A collection of objects providing information applicable to synchronous RS-232-like interfaces.
rs232SyncSDLCGroup1.3.6.1.2.1.10.33.7.1.4A collection of objects providing information applicable to synchronous RS-232-like interfaces running SDLC.
rs232Compliances1.3.6.1.2.1.10.33.7.2
rs232Compliance1.3.6.1.2.1.10.33.7.2.1The compliance statement for SNMPv2 entities which have RS-232-like hardware interfaces.

RFC description

RS-232 serial port hardware management and monitoring.

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