agent -- a piece of SNMP software running on a network device which retrieves or changes network management information at the request of an SNMP client. This may involve ``get'' or ``set'' operations on MIB information maintained by SMUX peers.
ASN.1 -- Abstract Syntax Notation One, the OSI language for describing abstract syntax; ASN.1 is used in SNMP messages.
client -- a piece of SNMP software, usually run on a network management station, which requests MIB information and receives responses from an SNMP agent.
ClosePDU -- a type of Protocol Data Unit issued either by an SNMP agent to an SMUX peer, or by an SMUX peer to an SNMP agent, to terminate an SMUX association. This PDU removes all the peer's MIB module registrations and closes the TCP connection between agent and peer.
Counter -- an object syntax type representing a non-negative integer, which increases monotonically until it reaches the maximum value (2[\31] - 1), when it wraps back to zero.
decode -- to convert a string of octets into an ASN.1 instance of a data type.
encode -- to serialize an ASN.1 instance of a data type into a string of octets.
export -- to register a MIB module; the process whereby an SMUX peer informs an SNMP agent that the peer is assuming responsibility for managing a MIB module.
Gauge -- an object syntax type representing a non-negative integer, which may increase or decrease, but which latches at a maximum value (2 - 1).
get -- an SNMP operation for retrieving network management information, in which the SNMP client issues a GetRequestPDU to an SNMP agent; for each variable in a GetRequestPDU, the named instance is retrieved (either by the agent or an SMUX peer) and returned to the SNMP client in a GetResponsePDU with the each variable's value field containing the information requested. If the instance is non-existent, the GetResponsePDU contains a noSuchName error code.
get-next -- an SNMP operation for retrieving network management information, in which the SNMP client issues a GetNextRequestPDU to an SNMP agent; for each variable in the GetNextRequestPDU, the instance which lexicographically follows the named instance is retrieved (either by the agent or an SMUX peer). If the end of the lexicographic space is reached, a GetResponsePDU is returned to the SNMP client containing a noSuchName error code. Otherwise, the GetResponsePDU returned contains the filled-in name and value fields of the requested variables.
instance -- an actual occurrence of an object which is manipulated by a management protocol such as SNMP and SMUX.
ipAddress -- an object syntax type representing an IP address.
MIB -- Management Information Base; a tree-structured naming convention that is used to access network data via a network management protocol such as SNMP.
MIB module -- a subtree of the MIB.
mosy -- the Managed Object Syntax-compiler (YACC-based) that reads the ASN.1 definitions of a MIB module and produces an output file which can be used by the SMUX library functions. mosy is invoked automatically when you execute the make command.
network management station -- a host running a network management protocol (SNMP) and network mangement applications which monitor and control network devices such as routers, gateways, hosts, and terminal servers; these devices run SNMP agent and/or SMUX peer daemons which perform the actual management operations requested by the network management station.
object -- an abstract management object with an associated syntax, access, status, and name (OBJECT IDENTIFIER); a managed object is a template -- it is the instances of the object which are actually manipulated by get, get-next, and set operations.
OctetString -- an ASN.1 primitive data type, taking zero or more octets as its value. Each byte in an octet string may take any value in the range 0 to 255.
OID -- an OBJECT IDENTIFIER; an object syntax type consisting of a sequence of non-negative integer values that traverses a tree (for example, 220.127.116.11). The OID denotes an authoritatively named object regardless of the semantics (for example, a standards document, an ASN.1 module, and so on) associated with the object.
OpenPDU -- a Protocol Data Unit sent by an SMUX peer to an SNMP agent to initiate an SMUX association with that agent. An OpenPDU contains authentication information (OID-password pair) which the agent compares to data specified for that peer in the configuration file /etc/snmpd.peers.
PDU -- Protocol Data Unit; a data object exchanged by protocol machines (such as management stations, SMUX peers, and SNMP agents) and consisting of both protocol control information and user data. PDU is sometimes used as a synonym for ``packet''.
peer -- a piece of software, running on a network device, which manages a specific MIB module. A peer receives requests from, and issues responses to, an SNMP agent via the SMUX protocol.
priority -- a peer registration request parameter which allows an SNMP agent to resolve conflicting registration attempts. All peer registration requests have an associated priority, which has an integer value in the range 0 (indicating highest possible priority) to (2 - 1). Many peers may register the same MIB module, but they must do so at different priorities. The peer with the highest registration priority for a given MIB module is consulted exclusively for all operations on objects in that module. See also the ``Priority'' section.
registration -- the process whereby an SMUX peer informs an SNMP agent that the peer is assuming responsibility for servicing management station requests involving objects contained in a specific MIB module (or subtree). See also priority.
RreqPDU -- a registration request Protocol Data Unit; issued by an SMUX peer to request registration for a specific MIB module at either a specific priority or at priority -1. See also priority.
RrspPDU -- a registration response Protocol Data Unit; issued by an SNMP agent in response to a peer's registration request. This PDU contains the integer priority value that the agent has assigned to the peer's MIB module registration. See also RreqPDU, registration, and priority.
set -- an SNMP operator; for each variable contained in the SetRequestPDU, the named instance is identified. If the named instance doesn't exist, or the instance doesn't allow writing, or the value supplied in the request is syntactically incorrect or contains an out-of-range value, a GetResponsePDU is returned with an appropriate error code. Otherwise, all the variables are written simultaneously and a GetResponsePDU is issued. See also ``Agent sets peer data'' section.
SOutPDU -- a type of Protocol Data Unit sent by an SNMP agent to an SMUX peer to initiate the second phase of a set operation. An SOutPDU can be either of two types: ``commit'' or ``rollback''. A commit SOutPDU instructs the peer to proceed with writing the new pending values to the variables in the SetRequestPDU. A rollback SOutPDU instructs the peer to forget the new pending values for the variables in the SetRequestPDU and to leave the existing values intact. See also ``Agent sets peer data'' section.
Time Ticks -- an object syntax type representing a non-negative integer which counts the time in hundredths of a second (0.01 sec) since some epoch; maximum value is 2 - 1.
trap -- a type of PDU sent by an SNMP agent or an SMUX peer to alert the management station to the occurrence of a noteworthy event. Traps are unsolicited PDUs: they are not responses to request PDUs.
VarBind -- a variable binding containing a name and a value. The value portion is only meaningful in non-error response PDUs, TrapPDUs, and SetRequestPDUs; it is meaningless in Get and GetNext requests. By convention, the value field for GetRequestPDUs and GetNextRequestPDUs is always an instance of the ASN.1 data type NULL.
variable -- a specific instance of a managed object; an object instance.