福州大学：《计算机网络管理》课程PPT教学课件（英文）Chapter 4 SNMPv1-Organization and Information Models

Chapter 4 SNMPv1 Organization and Information Models SNMP management is also referred to as Internet management.Any network that uses the TCP/IP protocol suite is an ideal candidate for SNMP management.SNMP network management systems can manage even non- TCP/IP network elements through proxy agents. SNMP management is the most widely used network management system (NMS).Most of the network components used in enterprise network systems have built-in network agents that can respond to a an SNMP network management system

Chapter 4 SNMPv1 : Organization and Information Models SNMP management is also referred to as Internet management. Any network that uses the TCP/IP protocol suite is an ideal candidate for SNMP management. SNMP network management systems can manage even non￾TCP/IP network elements through proxy agents. SNMP management is the most widely used network management system (NMS). Most of the network components used in enterprise network systems have built-in network agents that can respond to an SNMP network management system

Chapter 4 SNMPv1 Organization and Information Models 4.1 Managed Network:Case Histories and Examples Let us look at some real-world experiences that demonstrate the power of network management before learning how it is accomplished.As with any good technology,the power of technology can result in both positive and negative results.Atomic energy is a great resource,but an atomic bomb is not!A network management system is a powerful tool,but it could also bring your network down if it is not "managed"properly

Chapter 4 SNMPv1 : Organization and Information Models 4.1 Managed Network: Case Histories and Examples Let us look at some real-world experiences that demonstrate the power of network management before learning how it is accomplished. As with any good technology, the power of technology can result in both positive and negative results. Atomic energy is a great resource, but an atomic bomb is not! A network management system is a powerful tool,but it could also bring your network down if it is not "managed" properly

NMS 192.168.252.1102 92,168252. Router 2 Backbone Network Router 1 Hub 1 Hub2编 172.16.46.2 172.16.46.3 ooooooooo ooooooooo Figure 4.1 shows a managed LAN that was discovered by a network management system.We show here only a subnetwork of a larger network managed by the NMS

Figure 4.1 shows a managed LAN that was discovered by a network management system. We show here only a subnetwork of a larger network managed by the NMS

4.2 The History of SNMP Management SNMP management began in the 1970s.Internet Control Message Protocol (ICMP)was developed to manage ARPANET.ICMP is a mechanism to transfer control messages between nodes.A popular example of this is Packet Internet Groper (PING),which is part of the TCP/IP suite now.PING is a very simple tool that is used to investigate the health of a node and the robustness of communication with it from the source node.The ARPANET,which started in 1969,developed into the Internet in the 1980s with the advent of UNIX and the popularization of client/server architecture. Data was transmitted in packet form using routers and gateways.TCP/IP-based networks grew rapidly,The National Science Foundation officially dropped the name ARPANET in 1984 and adopted the name Internet

4.2 The History of SNMP Management SNMP management began in the 1970s. Internet Control Message Protocol (ICMP) was developed to manage ARPANET. ICMP is a mechanism to transfer control messages between nodes. A popular example of this is Packet Internet Groper (PING), which is part of the TCP/IP suite now. PING is a very simple tool that is used to investigate the health of a node and the robustness of communication with it from the source node. The ARPANET, which started in 1969, developed into the Internet in the 1980s with the advent of UNIX and the popularization of client/server architecture. Data was transmitted in packet form using routers and gateways. TCP/IP-based networks grew rapidly, The National Science Foundation officially dropped the name ARPANET in 1984 and adopted the name Internet

4.3 Internet Organizations and Standards 4.3.2 Internet Documents RFC was just what the name implies,a Request for Comments.The early RFCs were messages between the ARPANET architects about how to resolve certain problems.Over the years,RFC has become more formal. 4.4 The SNMP Model A network management system acquires a new network element through a management agent or monitors the ones it has acquired.There is a relationship between the manager and the agent.Since one manager is responsible for managing the designated functions of many agents,it is hierarchical in structure.The infrastructure of the manager-agent and the SNMP architecture that it is based on form the organization model

4.3 Internet Organizations and Standards 4.3.2 Internet Documents RFC was just what the name implies, a Request for Comments. The early RFCs were messages between the ARPANET architects about how to resolve certain problems. Over the years, RFC has become more formal. 4.4 The SNMP Model A network management system acquires a new network element through a management agent or monitors the ones it has acquired. There is a relationship between the manager and the agent. Since one manager is responsible for managing the designated functions of many agents, it is hierarchical in structure. The infrastructure of the manager-agent and the SNMP architecture that it is based on form the organization model

The TCP/IP suite is used for the transport mechanism. The functions and services are not addressed explicitly in SNMP management.The security management is covered in the administration model as part of communication.The services are covered as part of SNMP operations. 4.5 The Organization Model The initial organization model of SNMP management is a simple two-tier model.It consists of a network agent process,which resides in the managed object, and a network manager process,which resides in the NMS and manages the managed object.This is shown in Figure 4,5(a).Both the manager and the agent are software modules.The agent responds to a any management system that communicates with it using SNMP.Thus,multiple managers can interact with one agent,as shown in Figure 4.5(b)

The TCP/IP suite is used for the transport mechanism. The functions and services are not addressed explicitly in SNMP management. The security management is covered in the administration model as part of communication. The services are covered as part of SNMP operations. 4.5 The Organization Model The initial organization model of SNMP management is a simple two-tier model. It consists of a network agent process, which resides in the managed object, and a network manager process, which resides in the NMS and manages the managed object. This is shown in Figure 4,5(a). Both the manager and the agent are software modules. The agent responds to any management system that communicates with it using SNMP. Thus, multiple managers can interact with one agent, as shown in Figure 4.5(b)

SNMP SNMP SNMP Manager Manager Manager SNMP Agent .8 and SNMP Agent Network Network Element Element (a)One Manager-One Agent (b)Multiple Managers-One Agent Figure 4.5 Two-Tier Organization Models

SNMP a Manager 白2白8小 的A可A2 howlelt Proxy inemela Server Non-SNMP SNMP Managed Managed Objects Objects Figure 4.7 Proxy Server Organization Model

SNMP Manager 园 RMON Probe mnepA 9Mie Managed Objects howtel nem图 Figure 4.6 Three-Tier Organization Model

4.6 System Overview Figure 4.9 shows SNMP network management architecture.It portrays the data path between the manager application process and the agent application process via the four transport function protocols:UDP, IP,DLC (data link control),and PHY (physical).The three application layers above the transport layer are integrated in the SNMP process.The Internet model is concerned only with the TCP/IP suite of protocols and does not address the layers above or below it.Thus, layers 1 (physical)and 2 (data link control)in the transport layers can be anything of the users'choice. In practice,SNMP interfaces to the TCP/IP with UDP as the transport layer protocol.As the name implies, the SNMP protocol has been intentionally designed to be simple and versatile;this surely has been accomplished,as indicated by its success

4.6 System Overview Figure 4.9 shows SNMP network management architecture. It portrays the data path between the manager application process and the agent application process via the four transport function protocols: UDP, IP, DLC (data link control), and PHY (physical). The three application layers above the transport layer are integrated in the SNMP process. The Internet model is concerned only with the TCP/IP suite of protocols and does not address the layers above or below it. Thus, layers 1 (physical) and 2 (data link control) in the transport layers can be anything of the users' choice. In practice, SNMP interfaces to the TCP/IP with UDP as the transport layer protocol. As the name implies, the SNMP protocol has been intentionally designed to be simple and versatile; this surely has been accomplished, as indicated by its success