SNMP (Simple Network Management Protocol) based Network Management
Network Management: What is it? • Network management includes deployment, integration and coordination of the hardware, software, and human elements to monitor, test, poll, configure, analyze, evaluate and control the network and element resources to meet the real-time, operational performance, and Quality of service requirements at a reasonable cost.
Network Management: Why is it needed? • Lowers costs by eliminating the need for many administrators at multiple locations performing the same function • Makes network administration and monitoring easier and more convenient • Coherent presentation of data
OSI Network Management Model • ISO/OSI network management model defines a common frame of reference for network management, and provides an excellent framework for understanding the major functions that NMSs perform. • The OSI network management model incorporates the following five layers: – – – Performance management Fault management Configuration management Accounting management Security management
Functional Areas of Network Management (According to OSI Network Management Model) Performance Management – how smoothly is the network running Fault Management - reactive and proactive network fault management (deals with problems and emergencies in the network) Configuration Management – keeping track of device settings and how they function Accounting Management - cost management and charge back assessment Security Management - SNMP (Version 1 and 2) doesn’t provide much here
In-Band Versus Out-of-Band Management • When planning a distributed management solution, consider the path that the management data must take • There are two path options for network management information—in-band out-of-band • In-band management traffic travels along the network data path • Out-of-band management traffic alerts travel on a separate non-data path. An out-of-band management solution supports communications between management agents and the manager device, regardless of the status of the data network
In band/Out band Management Out-of-Band Management In Band Management
N/w Management arch.
Network Management Architectures 1) Management Entity • On the data collection end, two kinds of activities occur within a management utility or facility, called a management entity, whose job is to provide access to management data, controls, and behaviors: 1. Regular polling or sampling of management data occurs, whereby the management entity requests updates from managed devices to reflect recent status of the network being managed. 2. When alerts are received, appropriate responses must be generated
Network Management Architectures (contd. ) 2) Managed Device • A Managed device is a piece of network equipment that resides on a managed network. • At each managed device, a special piece of software(process) called a management agent responds to polls for collected data, where the management agent itself has custody of a management database (MDB) of information that it collects and maintains over time
Network Management Architectures (contd. ) 3) N/w Management Protocol • The protocol runs between managing entity and the managed device. • Allows the managing entity to query the status of the managed devices. • Agents can use the network management protocol to inform the managing entity of exceptional events.
SNMP & The OSI Model
Versions • Two major versions SNMPv 1, SNMPv 2 • SNMPv 1 is the recommended standard • SNMPv 2 has become split into: • SNMPv 2 u - SNMPv 2 with user-based security • SNMPv 2* - SNMPv 2 with user-based security and additional features • SNMPv 2 c - SNMPv 2 without security • SNMPv 3 - Future
Client Pull & Server Push • SNMP is a “client pull” model The management system (client) “pulls” data from the agent (server). • SNMP is a “server push” model The agent (server) “pushes” out a trap message to a (client) management system
The Internet- Standard Management Framework • SNMP is a tool (protocol) that allows for remote and local management of items on the network including servers, workstations, routers, switches and other managed devices. • Comprised of agents and managers • Agent - process running on each managed node collecting information about the device it is running on. • Manager - process running on a management workstation that requests information about devices on the network.
The Internet- Standard Management Framework (contd. ) SNMP network management consists of four parts: • Management Information Base (MIB) • A map of the hierarchical order of all managed objects and how they are accessed • Structure of Management Information (SMI) • Rules specifying the format used to define objects managed on the network that the SNMP protocol accesses • SNMP Protocol • Defines format of messages exchanged by management systems and agents. • Specifies the Get, Get. Next, Set, and Trap operations • Security and administration capabilities • The addition of these capabilities represents the major enhancement in SNMPv 3 over SNMPv 2
MIB-2 MIB-II Standard Internet MIB • Definition follows structure given in SMI • MIB-II (RFC 1213) is current standard definition of the virtual file store for SNMP manageable objects • Has 10 basic groups – system – interfaces – at – ip – icmp – tcp – udp – egp – transmission – snmp • If agent implements any group then is has to implement all of the managed objects within that group
Ports & UDP • SNMP uses User Datagram Protocol (UDP) as the transport mechanism for SNMP messages Ethernet Frame IP Packet UDP Datagram SNMP Message CRC • Like FTP, SNMP uses two well-known ports to operate: • UDP Port 161 - SNMP Messages • UDP Port 162 - SNMP Trap Messages
Four Basic Operations • Get Retrieves the value of a MIB variable stored on the agent machine (integer, string, or address of another MIB variable) • Get. Next Retrieves the next value of the next lexical MIB variable • Set Changes the value of a MIB variable • Trap An unsolicited notification sent by an agent to a management application (typically a notification of something unexpected, like an error)
Basic operations contd. . get_request get_response port 161 get_next_request Manager Agent set_request get_response port 162 trap port 161
Traps • Traps are unrequested event reports that are sent to a management system by an SNMP agent process • When a trappable event occurs, a trap message is generated by the agent and is sent to a trap destination (a specific, configured network address) • Many events can be configured to signal a trap, like a network cable fault, failing NIC or Hard Drive, a “General Protection Fault”, or a power supply failure • Traps can also be throttled -- You can limit the number of traps sent per second from the agent • Traps have a priority associated with them -- Critical, Major, Minor, Warning, Marginal, Informational, Normal, Unknown
Trap Receivers • Traps are received by a management application. • Management applications can handle the trap in a few ways: • Poll the agent that sent the trap for more information about the event, and the status of the rest of the machine. • Log the reception of the trap. • Completely ignore the trap.
Languages of SNMP • Structure of Management Information (SMI) specifies the format used for defining managed objects that are accessed via the SNMP protocol • Abstract Syntax Notation One (ASN. 1) used to define the format of SNMP messages and managed objects (MIB modules) using an unambiguous data description forma • Basic Encoding Rules (BER) used to encode the SNMP messages into a format suitable for transmission across a network
SNMP MESSAGE ENCODING • THE DESCRIPTION OF MIBS AND MESSAGE FORMATS IS BASED ON THE ASN. 1 SYNTAX • THE MAPPING FROM AN ABSTRACT SYNTAX UPON A TRANSFER SYNTAX IS DEFINED BY THE BASIC ENCODING RULES (BER)
Basic Message Format Message Length Message Version Community String Message Preamble PDU Header PDU Body SNMP Protocol Data Unit
VARIABLE BINDINGS SNMP PDU SNMP MESSAGE
SNMP Agents Two basic designs of agents • Extendible Agents • Open, modular design allows for adaptations to new management data and operational requirements • Monolithic Agents • not extendible • optimized for specific hardware platform and OS
Remote Monitoring (RMON) • The RMON MIB is used to monitor and administer remote segments of a distributed network • Within an RMON network monitoring data is defined by a set of statistics and functions and exchanged between various different monitors and console systems. Resultant data is used to monitor network utilization for network planning and performance-tuning, as well as assisting in network fault diagnosis. • RMON places agents, called network probes, at various locations on the distributed network • Probes are standalone devices that contain a NIC, a processor, memory, and software
Community Names • A community string is a password that allows access to a network device. It defines what "community of people" can access the SNMP information that is on the device. • Community names are used to define where an SNMP message is destined for. • Set up your agents to belong to certain communities. • Set up your management applications to monitor and receive traps from certain community names. • There actually three community strings for SNMP-speaking devices: • The SNMP Read-only community string • The SNMP Read-Write community string • The SNMP Trap community string
PROXY MANAGEMENT • A NODE MAY NOT SUPPORT SNMP, BUT MAY BE MANAGEABLE BY SNMP THROUGH A PROXY AGENT RUNNING ON ANOTHER MACHINE • TERM HAS TRADITIONALLY BEEN USED FOR DEVICES THAT : – – • TRANSLATE BETWEEN DIFFERENT TRANSPORT DOMAINS TRANSLATE BETWEEN DIFFERENT SNMP VERSIONS TRANSLATE BETWEEN SNMP AND OTHER MANAGEMENT PROTOCOLS AGGREGATE LOW LEVEL MANAGEMENT INFO INTO HIGH LEVEL INFO ETC NOWADAYS THE TERM DENOTES A DEVICE THAT FORWARDS SNMP MESSAGES, BUT DOESN’T LOOK AT THE INDIVIDUAL OBJECTS
SNMP Consoles, Tools, Utilities, and Key Files • There are many of these available, the lion’s share of the market belongs to three products: – HP Open View’s Network Node Manager (NNM) – IBM’s Tivoli Net View – Computer Associates’ Unicenter TNG • There also many smaller utilities that are helpful when supporting a management system (Novell Manage. Wise, Sun Micro. Systems Solstice, Microsoft SMS Server, Compaq Insight Manger, Snmp. QL - ODBC Compliant, Empire Technologies, Cinco. Networks Net. Xray, SNMP Collector Win 9 X/NT, Observer)
Architecture of NSM Products NSM products are made up of three layers: • World. View Layer: repository for the graphical visualization of the enterprise. – COR – Real World Interface – Worldview Application Interface • Manager Layer: – Agent Technology: Contains the agent facilities that monitor and determine the state of enterprise – Enterprise Management: A collection of integrated managers that control and automate a variety of functions and responses within the enterprise • Agent Technology Layer: Agents gather information from enterprise through remote access monitoring and control resource. Agents reside on or near managed objects and provide information to a management application.
Following steps outline what occurs architecturally when an agent detects a threshold breach on the device it is monitoring: • Agent identifies a threshold has been crossed for a resource it is monitoring. It passes this information to the SNMP administrator by way of the Distributed Services Bus. • The SNMP administrator takes the information from the Agent, encodes an SNMP Trap Protocol Data Unit and send it to the Manager. • The SNMP Gateway receives the Trap PDU, decodes it, and sends it to the Manager by way of DSB. • The Manager determines if the alert represents a change in status for the resource and, if so, passes the status update to the World. View Gateway by way of DSB. • The World. View Gateway then updates the status of the managed object in the COR.
About NSM Products • Supports management of multiple distributed domains. Each server can import the map of one or more servers. • Provides both local and remote access using the Remote Console Component. • Polling agents perform discovery of locally attached devices.
• Supports a multi-level hierarchy map. Each hierarchy can represent cities, buildings or sub networks. • Automatically lays out each map network as a tree, ring, or snaked bus topology. • Each map object uses a device specific or user selected icon, and the object color indicates the device status • Automatically generates scheduled daily, weekly and monthly statistic reports. Report format include graph, bar chart, distribution, and summary and can be exported to a variety of destinations.
Advantages of using SNMP • • • Standardized universally supported extendible portable allows distributed management access lightweight protocol