Definitions of Managed Objects for RS-232-like Hardware Devices
obsoleted by
- rfc-1659 — Definitions of Managed Objects for RS-232-like Hardware Devices using SMIv2
Extracted elements (25)
By convention and if possible, rs232PortIndex hardware port numbers map directly to external connectors, improving human operability by aligning logical identifiers with physical labeling.
Objects not applicable to all hardware types (e.g., async-only or sync-only parameters) are placed in separate table branches that are required when applicable and absent otherwise, keeping the base group minimal.
The RS-232-like MIB is positioned at the physical layer and is designed for complementary use with higher-level MIBs (Character MIB, PPP MIB); the physical-level MIB represents the lowest level regardless of which higher-level application uses it.
The rs232InSigTable and rs232OutSigTable contain entries only for signals the software can detect or assert, respectively, avoiding gaps or placeholder entries for unsupported signals in the signal tables.
The usefulness of error counters in this MIB depends on the presence of non-error character counts in higher-level MIBs, since error rates are only meaningful relative to total character counts.
The RS-232-like Hardware Port MIB covers RS-232, RS-422, RS-423, V.35, and other asynchronous or synchronous serial physical links with a similar set of control signals, not just RS-232 strictly.
The rs232AsyncPortTable maximum entry number is given by rs232Number, but entries need not exist for synchronous ports; similarly, rs232SyncPortTable entries need not exist for asynchronous ports.
When rs232AsyncPortAutobaud is enabled, a network management system may temporarily observe speed, parity, and character-size values different from what was previously set, due to the port autobauing to a detected input rate.
Implementation of the RS-232-like Hardware Device MIB is mandatory for all systems that have RS-232-like hardware ports supporting higher-level services such as character streams or network interfaces (e.g., Character MIB or PPP MIB).
Implementation of the rs232AsyncPortTable group is mandatory if the system has any asynchronous ports; otherwise the group is not present.
Implementation of the rs232SyncPortTable group is mandatory if the system has any synchronous ports; otherwise the group is not present.
The value of rs232PortIndex must remain constant at least from one re-initialization of the network management agent to the next, ensuring stable port identification across restarts.
rs232AsyncPortAutobaud controls whether a port automatically senses input speed. When enabled, the port may autobaud to values different from the administratively set speed, parity, and character size.
rs232AsyncPortTable (OID rs232 3) contains per-port asynchronous parameters: rs232AsyncPortBits (INTEGER 5..8), rs232AsyncPortStopBits (one/two/one-and-half/dynamic), rs232AsyncPortParity (none/odd/even/mark/space), and rs232AsyncPortAutobaud (enabled/disabled).
rs232InSigName and rs232OutSigName enumerate 11 RS-232-C hardware signals: rts(1), cts(2), dsr(3), dtr(4), ri(5), dcd(6), sq(7), srs(8), srts(9), scts(10), sdcd(11), referencing EIA Standard RS-232-C (August 1969).
rs232InSigTable (OID rs232 5) is indexed by (rs232InSigPortIndex, rs232InSigName) and contains entries only for signals the software can detect; each entry has rs232InSigState (none/on/off) and rs232InSigChanges (Counter of on↔off transitions).
rs232Number is a read-only INTEGER scalar (OID rs232 1) reporting the total number of RS-232-like ports regardless of their current state, which determines the size of rs232PortTable.
rs232OutSigTable (OID rs232 6) mirrors rs232InSigTable in structure, indexed by (rs232OutSigPortIndex, rs232OutSigName), but contains entries only for signals the software can assert rather than detect.
rs232PortTable (OID rs232 2) is a general port table indexed by rs232PortIndex, with entries containing: rs232PortType (other/rs232/rs422/rs423/v35), rs232PortInSigNumber, rs232PortOutSigNumber, rs232PortInSpeed (read-write, bps), and rs232PortOutSpeed (read-write, bps).
rs232PortType enumerates hardware types as INTEGER: other(1), rs232(2), rs422(3), rs423(4), v35(5), covering the range of RS-232-like serial interfaces managed by this MIB.
rs232SyncPortAbortedFrames counts frames aborted due to receiving an abort sequence since re-initialization while port state was 'up' or 'test', distinct from rs232SyncPortInterruptedFrames which counts frames lost due to modem signal loss.
rs232SyncPortClockSource specifies the bit rate clock source as internal(1), external(2), or split(3), where 'split' means the transmit clock is internal and the receive clock is external.
rs232SyncPortTable (OID rs232 4) contains per-port synchronous parameters: rs232SyncPortClockSource (internal/external/split) and five error counters for frame check errors, transmit underruns, receive overruns, interrupted frames, and aborted frames.
The asynchronous port table tracks three error counters (all Counter type, read-only): rs232AsyncPortParityErrs, rs232AsyncPortFramingErrs, and rs232AsyncPortOverrunErrs, counting errors since system re-initialization while port state was 'up' or 'test'.
Security issues are not discussed in this memo; no authentication, access control, or confidentiality considerations are specified for the RS-232-like MIB objects.