CLI Overview

Command-line interface (CLI) was conceived to make it easy for human operators and administrators to interact with networking equipment in particular, data-networking devices. It is reminiscent of the character-based command-line interfaces used with computer operating systems such as UNIX. This is actually not surprising at the end of the day, a router is nothing more than a special-purpose computer with a set of networking interfaces and a special-purpose operating system. In fact, the first...

Web Resources

The Web has many excellent sources of information. Readers are encouraged to conduct their own Internet searches. Just try a Google search on terms such as network management, command-line interface, SNMP, and service-level management. Searches on the various topics discussed in this book are sure to yield a wealth of information, as are the websites of vendors engaged in management technology. Here is a very short list of links that you may want to try. http www.simpleweb.org contains a wealth...

Management by Exception

Management by exception aims to relieve management applications of management tasks while things are going smoothly but involve them when something unusual occurs. This is akin to a sales clerk in a store who is allowed to ring up the register but needs to call a supervisor when an unusual scenario or unforeseen problem is encountered, such as handling a customer return, dealing with a stuck register, or completing a purchase that exceeds a certain amount. Management by exception often involves...

Management by Objectives and Policy Based Management

The idea behind management by objectives is that a management system establishes certain goals for a subordinate system, and the subordinate system translates these goals into the required lower-level actions to ensure that those goals are met. This way, the upper-layer management system can focus simply on setting overall policy for management of the network that establishes the management objectives. The subordinate system handles translating the policy into actions. The subordinate system...

Integration Scope and Complexity

As you have just seen, the scope of what needs to be integrated as part of management depends on the perspective. It can be observed that as the scope of integration grows, its complexity grows in two dimensions simultaneously horizontally and vertically. Horizontally, the number of devices and network technologies that need to be integrated increases. However, with growing network size and complexity, it is no longer sufficient to merely integrate and add more systems while still providing...

Limitations of Syntactic Information Mediation

As simple as the previous examples were, they show the limitations of syntactic mediation. We turn first to the syslog-to-SNMP gateway. Of course, the gateway does allow an SNMP manager to receive syslog messages without needing to understand and parse syslog. However, the traps produced by the mediator likely look a little different than what would have been emitted by a native SNMP agent at the device. To distinguish those traps, we use the terms mediated traps and native traps, respectively....

The Equipment Vendor

Equipment vendors are primarily in the business of selling networking equipment, not network management applications. Hence, traditionally equipment vendors have shown a tendency to limit investment in management application development. In general, they have been willing to settle for the minimum management capabilities that customers would allow them to get away with. That means that generally they would provide just the level of management capabilities needed to not inhibit equipment sales....

Of Schema and Metaschema

As mentioned in the previous section, the model that underlies the management information in a MIB is specified in a MIB definition. Some people call the model the schema, reminiscent of a database schema that constitutes the definition of the database tables. The underlying real world that is being abstracted by the model is often called the domain because it constitutes the subject domain that the model is all about. In the example of the previous section, the domain of the model is that of...

Common Platform Infrastructure

Like a computer operating system, a management platform provides a set of infrastructure that management applications commonly need and that developers of applications for the platform consequently do not have to build themselves. This infrastructure goes beyond building blocks that are incorporated into application code in the form of software libraries. Instead, it involves common services that live in their own process space during runtime. Applications that need to use those services...

Netconf Datastores

Netconf picks up on the notion that the configuration information of devices can be thought of and handled as being contained in a datastore (one word, per the Netconf spelling) that can be handled like a file. In essence, a configuration datastore corresponds to a device's config file the set of configuration statements that need to be executed to bring the device into its desired configuration state. As a protocol, Netconf provides the operations that are necessary to manage those datastores....

Structure of Management Information Overview

In SMI, MIB definitions are specified as MIB modules. A MIB module generally serves a particular purpose, such as to define management information related to a device's communication interfaces or to a voice-mail server feature that is embedded on a particular type of device. Accordingly, the MIB of any particular device instantiates multiple MIB modules, each of which represents one aspect of the managed device, as Figure 6-11 illustrates. Again, the term MIB is often used synonymously with...

Instantiation in an Actual MIB

So far, we have described how a model to represent management information is defined in SMI and how different object types are identified through their OIDs. We have also mentioned that some of the object types can be instantiated once, others multiple times. But how are those instances identified during runtime in an actual MIB This is one of the stranger aspects of SNMP and a little counterintuitive at first. Object instances in a MIB are considered to be conceptually part of the same object...

Mediation Between Management Protocols

Mediation at the management protocol level involves translating management messages of one protocol into management messages of another one specifically, mapping between the management primitives. From a naive point of view, this should be relatively straightforward if the capabilities between the protocols that are involved are equivalent. In this case, it should be sufficient to essentially perform a syntactic transformation that can occur during runtime. For example, for mediation from SNMP...

The Managed Device as a Conceptual Data Store

A MIB is best thought of as a conceptual data store. Managers can retrieve management information from the MIB by directing corresponding requests at the management agent for example, using a get operation. In many cases, they can also manipulate and modify the information that is contained in the MIB for example, using a set, a create, or a delete operation. The MIB, of course, is not the same as a database. The MIB does not store information about the real world (the actual managed device) in...

Syslog Protocol

For a long time, there was no true standard that syslog messages had to follow. As mentioned, syslog originated from messages that were logged by the UNIX operating system. However, syslog has been treated just as a loose recommendation and was never rigorously specified as a standard. Consequently, over time, different variations of syslog message formats proliferated across different vendors and device types. For example, they differed on details such as the precise format that is used to...

Anticipating Problems Before They Occur

Being able to monitor current service levels is nice, but when it is detected that service level objectives are violated, the damage is already done. Therefore, it would be nice to also anticipate a problem before it occurs. This way, it might still be possible to take countermeasures to avert service level objective violations. Accordingly, what is needed is a service level forecast, not unlike a weather forecast of course, in this case, the course of forecast events can still be influenced. A...

Netconf and XML

One of the distinctive features of Netconf is the fact that it uses XML as encoding for its management operations. XML is a cornerstone of web technology it is a language that allows for the representation of information in a structured way. Obviously, a discussion of XML goes way beyond the scope of this book there is a rich set of literature for the interested reader. We just briefly discuss some of the most fundamental aspects as far as they are relevant for the remainder of the discussion....

Management Agent

To be managed, a network element must offer a management interface through which a managing system can communicate with the network element for management purposes. For example, the management interface allows the managing system to send a request to the network element. This could be, for example, a request to configure a subinterface, to retrieve statistical data about the utilization of a port, or to obtain information about the status of a connection. Likewise, the network element can send...

The Role of Standardization and Information Models

In Chapter 4, we discussed the role of standards in network management. It should be mentioned that standardization also plays a big role in integration among different components. After all, the intent of network management standards is to facilitate interoperability between different systems, which facilitates their integration. Standardization concerns not only interfaces between managing and managed devices, but also interfaces between different management systems. We discussed this in...

The Impact of the Metaschema on the Schema

In the fine arts, the media that an artist uses has a great influence over the type of artwork that results. For instance, the character of a painting is different if the artist uses water colors, oil colors, crayons, or a pencil. The difference is even more dramatic if clay is used, resulting in a sculpture instead of a drawing or a painting. Of course, each medium can be used to model the same aspect of the real world, such as a person. The resulting model is called a portrait. In network...

Chris Network Administrator for a Medium Size Business

Together with a colleague who is currently on vacation, Chris is responsible for the computer and networking infrastructure of a retail chain, RC Stores, with a headquarters and 40 branch locations. RC Stores' network (see Figure 2-4) contains close to 100 routers typically, an access router and a wireless router in the branch locations, and additional networking infrastructure in the headquarters and at the warehouse. The company has turned to a managed service provider (MSP) to...

Use of CLI as a Management Protocol

Strictly speaking, CLI is not a management protocol at all. It is a command-line interface, intended for human users who interact with the device directly, not through a management application that abstracts away the details of how the communication with the device takes place. Therefore, it is perhaps a bit unfair to point out some challenges that are associated with CLI related to uses that it was not designed to support. However, management applications are faced with the problem of how to...

Subcontracting Management Tasks

In a management hierarchy, certain management tasks are subcontracted to different systems. In effect, the subcontracted systems constitute management proxies To the subordinate system, it appears that the proxy is the manager. However, the manager proxy is really only a conduit, acting on behalf of another management system that is invisible to the managed system in the agent role. You've already seen one example of management hierarchies the specialization of applications along the different...

Layer Example

Netconf Protocol Layers

The transport protocol layer provides for the underlying communication transport. Different transports are possible and can be used for example, Secure Shell (SSH) and Block Extensible Exchange Protocol (BEEP). Those protocols are specified elsewhere and are not specific to management. What Netconf does is specify the requirements that a protocol must meet so that it can be used. (It also specifies bindings for a few transports, including the ones mentioned.) For example, the transport must...

The Third Party Application Vendor

Third-party management software application vendors fill the management application gap that equipment vendors leave open. For one, management application software developed by an equipment vendor tends to support only equipment of that particular vendor. Even if multivendor support is provided, preferential treatment is given to the vendor's own equipment, in terms of both available features and the timeline at which the support becomes available. At the same time, as stated previously, in...

Management Process and Organization Of Help Desks and Cookie Cutters

Management interoperability, management function, and management layers capture different technical aspects of network management. However, network management also involves a nontechnical dimension how to organize the management. This includes the processes that are required to ensure that the networks are run smoothly and reliably, as well as the structure of the support organization. Those nontechnical aspects are the topic of the management process and organization viewpoint. The management...

Alarm and Event Filtering

Let us first turn our attention to filtering, not just of alarms, but of events in general. To focus an operator's or a management application's attention on those events that really matter, it is important to block out as many irrelevant or less important events as possible. This is analogous to the way in which the human brain is able to deal with the massive flow of data that it is constantly exposed to, such as sounds, visual images, and sensory data. To focus, it filters out massive...

Basic Alarm Management Functions

We start the discussion of alarm management with the more basic functions collecting alarms, maintaining accurate and current lists of alarms, and visualizing alarms and network state. The most basic and, at the same time, most important task the task that everything else builds on consists of simply collecting alarms from the network and making sure that nothing important is missed. This includes receiving the alarms and storing them in memory so that they can be further processed by an...

Management by Delegation

Management by delegation involves an upper-layer management system delegating certain tasks to lower-layer systems in some cases, the managed systems themselves. This is a very common theme that can be found across the various management functional areas. In many cases, tasks suitable for delegating are routine tasks that do not require interaction with a management operator or administrator. They involve a relatively low level of intelligence but often require sifting through a large amount of...

Other Material Related to This Book

There Is No Such Place As America Stories. Delacorte Press, 1970. This book contains the short story A Table Is a Table, mentioned in Chapter 6. Brown, A., A. Keller, J. Hellerstein. A Model of Configuration Complexity and Its Application to a Change Management System. In Proceedings of the 2005IEEE IFIP International Symposium on Integrated Network Management, p. 631-644, 2005. This paper contains an analysis of operational complexity that is associated with configuration...

Pat A Network Operator for a Global Service Provider

Pat works as a network operator at the Network Operations Center (NOC) of a global service provider that we shall call GSP. She and her group are responsible for monitoring both the global backbone network and the access network, which, in essence, constitutes the customer on-ramp to GSP's network. This is a big responsibility. Several terabytes of data move over GSP's backbone daily, connecting several million end customers as well as a significant percentage of global Fortune 500...

Backup and Restore

If you are a PC user (and, chances are, you are), you are aware of the importance of protecting your data by performing regular backups. You never know when your hard disk will bite the dust or whether your PC will contract a virus that could destroy your PC's file system. Having a backup of your data in such cases enables you to recover. With backups in place, contracting a virus or needing to replace your hard drive is still annoying, but it beats by far simply being wiped out. Likewise, the...

Standards and Industry Recommendations

Schoenwaelder, J. Case, M. Rose, S. Waldbusser. Conformance Statements for SMIv2. IETF RFC 2580, April 1999. McCloghrie, K., D. Perkins, J. Schoenwaelder, J. Case, M. Rose, S. Waldbusser. Structure of Management Information Version 2 (SMIv2). IETF RFC 2578, April 1999. McCloghrie, K., D. Perkins, J. Schoenwaelder, J. Case, M. Rose, S. Waldbusser. Textual Conventions for SMIv2. IETF RFC 2579, April 1999. These above three references specify SMIv2. RFC 2578 is the...

Decomposing Service Level Parameters

In many cases, a service is realized by a combination of multiple pieces. We already encountered the example of a hosted application service depicted in Figure 11-4. In this example, an application service provider hosts a set of applications in a data center that is accessible over a network. Multiple pieces are involved in providing this service A networking piece is used to provide connectivity to the host from the edge of the data center, with traffic possibly traversing a content switch...

Get Next Request

A manager uses a get-next request to retrieve management information from an agent, just as with a get request. However, contrary to an ordinary get request, the OIDs in the variable bindings do not specify the objects that are to be retrieved directly. Instead, for each OID specified in the request, the agent is requested to return the object with the OID that comes in lexicographical order right after that OID. An OID supplied with a get-next request can be but does not have to be an OID of...

An Example MIB2

Let us now consider an excerpt from MIB-2. For brevity, portions of the definition are omitted. The symbol is used to indicate where information is omitted within the definition excerpts. We start by taking a look at the header of the MIB module. mib-2 OBJECT IDENTIFIER mgmt 1 This definition establishes mib-2 as a new node underneath a supernode called mgmt inside the Internet object identifier tree. (mgmt is imported from another standard it identifies the subnode that is reserved for...

Management Styles

We have now seen that management tasks can be distributed across many systems and that distributed management functionality can be deployed in different ways. The remaining question is how to best make use of these capabilities. A lot of business administration literature discusses different business management approaches. Actually, scaling the task to manage networks is not all that different from scaling the task to manage other business functions, such as managing people in an organization....

Managing Oversubscription Risk

Of course, oversubscribing network resources can be risky. At times every user might simultaneously access the service. In such cases, something will have to give. Also, sometimes the usage of service between different users might not be as statistically independent as the service provider would like. An example of such a usage pattern might be in case of digital TV subscribers at a time when the Soccer World Cup final is on. When this scenario occurs, not only is a larger percentage of users...

About the Author

Alexander Clemm, Ph.D. is a Senior Architect with Cisco Systems. He has been involved with integrated management of networked systems and services since 1990. Alex has provided technical leadership for many network management development and engineering efforts from original conception to delivery to the customer. They include management instrumentation of network devices, turnkey management solutions for packet telephony and managed services, and management systems for Voice over IP...

Stateful Mediation

Ideally, management mediation follows a simple pattern The management gateway receives a request message from a manager and translates it into an equivalent request message for the agent. When a response or event message is received, the gateway translates it into an equivalent response or event message that it sends back to the manager. The pattern is very straightforward and clean management mediation involves not much more than transforming a message that the gateway can forget about after...

Networking for Management

One way in which network elements can be connected to a management system is through the network element's management port. For most routers, this is a serial interface. It is possible to connect a terminal, such as a notebook computer, directly to that serial interface using a serial cable, as illustrated in Figure 3-10. The terminal thus connected to a network device is typically referred to as a craft terminal, in reference to the craft technician who typically uses it. The craft terminal...

Function Viewpoint What Can I Do for You Today

The function viewpoint establishes what functions are supported that is, what services a manager can expect from an agent. This includes the type of requests that a manager can make and that the agent supports. It also includes capabilities that an agent has to send event messages to notify a manager of certain event occurrences. At this point, we've covered the need to establish connectivity, as well as the need for rules for the exchange of management messages. Some additional aspects that...

Sandy Administrator and Planner in an Internet Data Center

Sandy works in the Internet Data Center for a global Fortune 500 company, F500, Inc. The data center is at the center of the company's intranet, extranet, and Internet presence It hosts the company's external website, which provides company and product information and connects customers to the online ordering system. More important, it is host to all the company's crucial business data its product documents and specifications, its customer data, and its supplier data. In addition,...

Managed Technology Manageability

Manageability refers to the collective set of properties of an entity (that is, a device or a network) that allow it to be managed. Those properties can largely be attributed to the entity's management instrumentation the management interfaces that it exposes and the capabilities that those interfaces provide. However, it involves other properties as well that make the entity easier to manage, such as capabilities that reduce the need of a device to be managed in the first place. Manageability...

Assessing Network Management Effectiveness

Now that we have reviewed the factors and management features that contribute to management's business impact, how can we actually assess how well management is working What is needed is a set of metrics by which the effectiveness of management can be measured. An understanding of such metrics, along with an understanding of the different ways in which management technology contributes to those metrics, can provide invaluable guidance for determining priorities in the development and deployment...

Information Retrieval Polling and Polling Based Management

Perhaps the most prevalent type of request response management interactions involves requests for information by a manager, in which the manager interrogates the agent. This is also referred to as polling. The basic pattern is very straightforward The manager asks the agent for a particular piece, or pieces, of management information. The agent checks the validity of the request and retrieves the requested information. The agent then responds, providing the requested information in the response...

The Pros and Cons of a Dedicated Management Network

Carrying management traffic out of band can quickly result in building a fairly sophisticated network that is dedicated just to network management. This network can exist in addition and in parallel to the network that you are trying to manage a dedicated network that allows your management systems to communicate with the network elements that they are managing. However, using out-of-band management communications does not necessarily imply the use of a dedicated management network that is...