agent--A process in the device that handles SNMP requests.
alarm--A message that is triggered when defined values cross a given threshold. For instance, you can specify the number of Ethernet collisions, plus a time interval, such as 1 second, and a threshold, such as 60 collisions. Given this scenario, an alarm is generated when the number of Ethernet collisions exceeds 60 in 1 second.
event--The action that is triggered as result of an alarm. Alarms and events are logically connected. For example, when the number of collisions on an Ethernet segment exceeds 60 per second, the corresponding event can cause a trap message to be sent to one or more management stations.
An event is generated by the RMON agent, which could be triggered by a threshold crossing. An event can be signaled as a trap, a new entry in the MIB log table, both, or neither.
inform request--A message sent by an SNMP agent to a network management station, console, or terminal to indicate that a significant event occurred. SNMP inform requests are more reliable than traps because an inform request acknowledges the message with an SNMP response protocol data unit (PDU). If the manager does not receive an inform request, it does not send a response. If the sender never receives a response, the inform request can be sent again. Thus, informs are more likely to reach their intended destination.
Management Information Base--See MIB.
MIB-Management Information Base. Database of network management information that is used and maintained by a network management protocol such as SNMP. The value of a MIB object can be changed or retrieved by SNMP commands, usually through a network management system. MIB objects are organized in a tree structure that includes public (standard) and private (proprietary) branches.
MPLS--Multiprotocol label switching. MPLS is a method for forwarding packets (frames) through a network. It enables routers at the edge of a network to apply labels to packets (frames). ATM switches or existing routers in the network core can switch packets according to the labels.
Multiprotocol Label switching--See MPLS.
Simple Network Management Protocol--See SNMP.
SNMP--Simple Network Management Protocol. Management protocol used almost exclusively in TCP/IP networks. SNMP provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance, and security.
threshold--The range in which you expect your network to perform. If a performance exceeds or goes below the expected bounds, you can examine these areas for potential problems. You can create thresholds for a specific device.
trap--Message sent by an SNMP agent to a network management station, console, or terminal to indicate that a significant event occurred. Traps are less reliable than inform requests, because the receiver does not send an acknowledgment when it receives a trap. The sender cannot determine if the trap was received.
VSI--Virtual Switch Interface. A proposed common control interface to Cisco switches. The VSI can manage connections and discover configuration information about the switch.
VSI controller--A controller, such as a PNNI SVC controller, Portable AutoRoute or MPLS controller, that controls a switch using the VSI.
VSI master --A process implementing the master side of the VSI protocol in a VSI controller. Sometimes the whole VSI controller might be referred to as a "VSI Master," but this is not strictly correct. Also, the VSI master is a device that controls a VSI switch, for example, a VSI Label Switch Controller.
VSI slave --A VSI slave is either of the following:
- A switch (when one router controls one slave) or a port card (when one router controls more than one slave) that implements the VSI.
- A process implementing the slave side of the VSI protocol.