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Since it was developed in 1988, the Simple Network Management Protocol (SNMP) has become the de facto standard for internetwork management. SNMP has a number of advantages that contribute to its popularity. Because it is a simple solution, requiring relatively little code to implement, vendors can easily build SNMP agents into their products. SNMP is extensible, allowing vendors to easily add network management functions. And SNMP separates the management architecture from the architecture of the hardware devices, which broadens the base of multivendor support. Perhaps most importantly, unlike other so-called standards, SNMP is not a mere paper specification, but is an implementation that is widely available today.
This book, the sixth volume in the Network Troubleshooting Library, discusses network management in general, and SNMP in particular.
In a nutshell, a network management system contains two primary elements: a manager and agents. The manager is the console through which the (human) network administrator performs network management functions. Agents are the entities that interface to the actual devices being managed. Bridges, routers, switches, or network servers are examples of managed devices that contain managed objects. These managed objects might be hardware, configuration parameters, performance statistics, and so on, that directly relate to the current operation of the device in question. These objects are arranged in what is known as a virtual information database, called a management information base (MIB). SNMP allows managers and agents to communicate for the purpose of accessing these objects.
In order to fully understand the depth of network management, lets discuss these concepts one chapter at a time.
Chapter 1 provides an overview of the concepts of network management. Individual sections discuss the OSI, IEEE, and Internet network management standards. Other sections consider architectures from key vendors that support these standards: Asanté Technologies, Cabletron Systems, Hewlett-Packard, Novell, Sun Microsystems, and Tivoli Systems.
SNMP is only part of what is known as the Internet Network Management Framework. Chapters 2, 3, and 4 discuss individual sections of that framework. In order, these topics are the structure of management information (SMI), management information bases (MIBs), and SNMP itself.
The SMI provides a mechanism for describing and naming the objects being managed. This structure allows the values of these objects to be retrieved and manipulated, that is, managed. It accomplishes this by using a message description language, defined by ISO 8824, known as the Abstract Syntax Notation One (ASN.1). ASN.1 is used to define the syntax, or form, of a management message. Once this syntax has been specified with ASN.1, the Basic Encoding Rules (BER)from ISO 8825encode that message into a format that can be transmitted on a LAN or WAN.
The MIBs more precisely delineate the managed objects and organize these objects for ease of use. Different types of MIBs are available, including the Internet-standard MIB, defined in Request for Comments (RFC) documents 1212 and 1213; the remote monitoring MIBs, defined in RFCs 1513, 1757, and 2021; and numerous private enterprise MIBs that vendors define specifically for their products.
SNMP completes the story by providing a mechanism for the manager to communicate with the agents. This communication involves reading the values of the objects within a MIB and altering the values as appropriatein other words, managing the objects.
Enhancements, known as SNMP version 2 (SNMPv2), extend the capabilities of this popular protocol. Chapter 5 provides an overview of the management and security improvements found in SNMPv2.
Since SNMP is an Application Layer protocol, it must rely on other protocols at the lower OSI layers for other communication functions. Chapter 6 studies these protocols. For example, the User Datagram Protocol (UDP) transports the SNMP message through the internetwork. The Internet Protocol (IP) provides Network Layer functions, such as addressing, for the datagram. A third protocol, such as Ethernet or token ring, then delivers the information to the local network.
Once we have studied the protocols, we can look at examples of their use. Chapter 7 offers twelve case studies that detail the use of SNMP in managing actual networks.
With this information, youll have a full understanding of the real-world, practical applications of this popular network management standard.
Why This Book is for You
Managing Internetworks with SNMP, the sixth volume in The Network Troubleshooting Library, is a comprehensive guide and reference for network managers and administrators responsible for maintaining a complex internetwork. This book will give you a clear understanding of SNMP and SNMP version 2, the protocols developed by the Internet community to simplify the management of internetworks. It is packed with illustrations, case studies, and helpful examples that give you the techniques and know-how youll need to maintain a productive LAN or WAN using the SNMP.
Some of the topics covered in Managing Internetworks with SNMP are network-management concepts and standards from ISO, IEEE, and the Internet. There is also an analysis of network management architectures from Asanté Technologies, Cabletron Systems, Hewlett-Packard, Novell, Sun Microsystems, and Tivoli Systems. Additionally, the book provides you with a tutorial on the Structure of Management Information (SMI), including ASN.1 encoding examples. Management Information Bases (MIBs), including MIB-I and MIB-II, the Remote Monitoring MIBs, RMON, and RMON2, plus private enterprise MIBs defined by vendors, are also covered in detail.
Find out about SNMP version 2 and the enhancements it provides in areas of bulk data retrieval and multiprotocol-transport support. Other areas discussed are SNMP operation, including the Protocol Data Unit (PDU) formats and application examples, and lower-layer protocol support for SNMP, including UDP, IP, ICMP, ARP, and RARP. Real-world experience is provided in case studies taken from live internetworks demonstrating SNMP in use. Use the appendices, which are packed with vendor information and Internet network-management parameters, as a handy reference.
If you are responsible for a complex internetwork, put this book next to your network management console.
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