Multiplex communications – Pathfinding or routing – Through a circuit switch
Reexamination Certificate
1999-07-09
2002-05-07
Hsu, Alpus H. (Department: 2662)
Multiplex communications
Pathfinding or routing
Through a circuit switch
C370S395430, C370S397000, C370S409000, C711S206000, C714S003000
Reexamination Certificate
active
06385197
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the management of network switches and more particularly to a mechanism for simplifying the maintenance of the ports of a network switch.
Network management is defined as the management of network devices, such as workgroup hubs, switches, routers, bridges, and so on, as well as the management of the wires interconnecting them.
FIG. 1
shows a typical network management model
100
. The underlying base consists of the network management applications
110
used to manage the network. These management applications should have a consistent end-user interface and preferably a command data repository. It goes without saying that the user interface must be intuitive, user friendly, customizable, and consistent across all the applications. A common data repository
120
is desirable to avoid duplication of data and to allow access to the stored information by all applications. In addition, network management applications
110
should snap together seamlessly with desktop and business management applications.
The first standard for network management evolved into a specification that became known as SNMP (Simple Network Management Protocol). It was based on the TCP/IP protocol stack and was given the request for comment (RFC) number
1067
by the Internet Engineering Task Force (IETF). The workhorse of the SNMP specification is the Management Information Base (MIB). The MIB is a collection of information (or objects) about the managed device. Although the term MIB can be used to mean many different things, we use it to mean the actual data stored in an SNMP device or the description of that data. These MIB objects are standardized across a class of devices, so a management station can retrieve all object information from various devices or cause an action to take place at an agent by manipulating these objects. The configuration settings of a device can also be changed by this method.
By embedding SNMP within data communication devices, multivendor management systems can manage these devices from a central site and view information graphically. The many SNMP management applications available today usually run on most of the current operating systems, such as UNIX, Windows (TM)
98
, and Windows NT (TM) 5.0. Most high-end products are designed to cope with relatively large networks and thus run on powerful machines using the scaleable UNIX operating system.
The SNMP operational model is based on four elements: the management station, the management agent, the network management protocol, and the Management Information Base (MIB). The management station serves as an interface tool to the managed elements of the network. The management station usually has a graphical user interface that is used to monitor and control the network via a network interface card (NIC).
FIG. 2
shows a network system
200
comprising a network manager
210
and a network agent
220
. In this example, the network management protocol used for intercommunication between the management station and the agents is actually called SNMP and has the following defined functions:
1. Get enables the management station to retrieve the information objects from the agent.
2. Set allows the management station to set the values of the management objects at the agent.
3. GetNext allows the management station to retrieve the next sequential information in the management objects from the agent.
4. Trap is an unsolicited message from the agent to the management station that notifies the management station of any important events.
A managed device has a management agent that responds to requests for information and requests for actions from the management station. This agent may also provide the management station with unsolicited information by means of a trap. Key network devices, such as hubs, routers, and bridges, must therefore provide this management agent (often referred to as an SNMP agent or as being SNMP-capable) for them to be manageable via the SNMP management station.
In general, there is a standard way of describing the objects contained in a MIB. But for a management station to understand and access objects on different devices, the representation of particular resources must be the same on each node in the network. The structure of management information, which is specified in RFC 1155, defines the general framework within each MIB and can be defined generically and constructed to ensure consistency. In addition, each enterprise can define its own private MIBs to provide more detailed information about its specific managed devices. The problem with a generic MIB is that the objects defined therein are sometimes not sufficient for detailed management of particularly network devices. This is especially true with the new Layer
2
/
3
switches, the private MIB is important with these devices because each vendor talks to its switch differently. This means each vendor must supply detailed information via the enterprise-specific private MIB. Management applications use private MIBs to provide detailed, expanded views of the devices, to map out topologies of networks on the management platforms, and to configure and control switched environments containing virtual LANs (VLANs) and segmentation.
As mentioned above, basic SNMP capability alone does not really give the user good enough information about the LAN as a whole, but rather information about devices on the LAN. Therefore, an essential extension to SNMP is RMON capability. It should be noted that RMON is especially useful in monitoring and managing LANs.
RMON was drafted by the IETF and became a proposed standard in 1992 as RFC number 1271. The RMON specification was developed to provide traffic statistics and analysis on many network parameters for comprehensive network fault diagnosis, planning, and performance tuning. Ethernet was the initial focus and is described in the RFC 1271, but the remote monitoring functions were also extended to Token Ring in 1993 as RFC 1513.
RMON provides a standard set of MIBs that collect rich network statistical information not available through the basic SNMP MIBs. This information is basically everything you ever wanted to know about switches, so it is crucial in the management of network systems. RMON allows proactive network diagnostics by utilization of its powerful Alarm group. The Alarm group enables thresholds to be set for critical network parameters to automatically deliver alerts to centrally located management consoles. This is especially critical when managing Gigabit Ethernet switches, because full-wire speed management at that speed is virtually impossible.
RMON is especially critical for managing switches from a remote location because a switch keeps a full MIB information on a per-port basis, not a per-device basis. If you used regular SNMP to monitor a switch, port by port, it would result in a huge amount of SNMP traffic. With RMON support internal to the switch, this can be a quick and easy task. An RMON-enabled switch is responsible for collecting and acting on its own data as well as forwarding information to a central management station.
On shared segments, the traffic on a hub is echoed on all the ports. This means that there is no problem attached an RMON probe to one of the ports: all data will be seen by this probe and analyzed. In a switch, however, there is only port-to-port traffic. When the client on switch
1
talks to the server attached to port
3
, for example, the probe connected to port
5
has no way of seeing this traffic unless one internal switch mechanism is put in place. This mechanism is often called port mirroring and is implemented by the switch itself. The user can configure different criteria for data to be steered to a monitor port.
One of the most important functions performed by network management is the configuration management of the system.
Configuration management consists of two major elements. One is the tracking of the physical and logical configuration of your network, and the second pertains to the conf
Allied Telesyn International Corp.
Cooley & Godward LLP
Hsu Alpus H.
Qureshi Afsar M.
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