The MIB comprises one base object and four tables. The tables contain objects for
all ports, asynchronous ports, and input and output control signals.
Character Group
The Character group 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. The DECagent 90 supports the RS-232-like MIB for the
DECserver 90L and the DECserver 90L+. Another common hardware example
is a parallel printer port, 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. 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 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 MIB treats such situations with
benign neglect. A port may indicate that it is running as a network character
stream device. If it does, this could imply the existence of an entry in the
Interfaces table.
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.
MIB Groups and Communities C–5
Содержание DECagent 90
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