Network Management Chapter 3

A management network is the network that allows managers and agents to communicate with each other A production network is the network that carries client traffic These two networks can be separate, or they can share the same physical network

Management
Systems provide tools to manage the network such as
• monitoring applications • service provisioning systems • craft terminals


Management systems are applications that interact with the network They are not part of a network Production networks will function normally even if the management system fails



Network elements can be connected to a management system via management ports Routers, for example can be connected to a computer terminal via a serial interface Technicians enter commands to configure and troubleshoot the network device



Management communications may use a dedicated network that is physically separate from the production network Traffic can also be carried on the production network The management network may be overlaid on top of the production network


Management communication is inherently asymmetrical Network elements play the role of ―agents‖ that support a managing application (―manager‖) by responding to manager requests and notifying it of unexpected events
a view of a devices manageable features data in the database constitutes management information The MIB resides on the agent, but a cached version may be stored on a manager

A second way to manage a network element is through its Ethernet port
◦ This allows the network element to be identified by its IP address ◦ This configuration can be managed by SNMP ◦ This is the preferred way of managing a network
◦ Management traffic carried over the production network competes with other networking traffic ◦ Although low in volume, management traffic can be bursty and of non-negligible volume ◦ The amount of management traffic can be sufficient to interfere with other applications

This minimizes network traffic caused by repeated requests for the same information
translates requests from the management interface into operations that retrieve information from a MIB The agent logic maps the names of different MIB counters to the actual registers where the information is stored agent logic can include ―embedded management intelligence‖ that can perform pre or post processing of requests



SNMP agents use UDP and port 161 for management requests Packets specifically addressed to a network element are inspected by the element The NE then passes the packet to its SNMP agent process
This relationship is a client/server relationship with one or a few clients and many servers


software that provides functionality for an agent a network element can actually contain several management agents, each with its own management interface that supports different purposes (reporting, configuring, etc)
The Basic Ingredients ofBiblioteka Network Management
After you have read this chapter, you should be able to Explain the terms manager and agent Describe Management Information Bases (MIBs) Explain how management agents, managed devices, and MIBs relate to each other Explain the difference between in-band and outof-band management communications State the pros and cons of dedicated management networks Describe the role of Network Operations Centers (NOCs)

Reliability

Avoiding Interference
◦ management traffic is separated from traffic on the production network ◦ If a segment on the production network fails, management traffic on a dedicated network can reach the problem area
◦ a dedicated management network is a separate network ◦ This comes with a huge price tag that results in significant additional cost
The three main parts of a Management Agent are a management interface a Management Information Base the core agent logic




handles management communications supports a management protocol allows managing applications to make requests to network elements and receive responses allows agents to send unsolicited messages to alert the manager of events that occur on network elements

Managed devices are called network elements
(NEs)

A management interface that can send requests to the device is a pre-requisite For example, a request for data regarding utilization of a port can be made if the port has management capabilities Network elements can also send responses to the managing system Responses can be solicited or unsolicited, such as when an unexpected event occurs