SNMP Simple Network Management Protocol based Network Management

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

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

N/w Management arch.

Network Management Architectures 1) Management Entity job is to provide access to management data, controls, and behaviors: 1. Regular polling or sampling of management data – the management entity requests updates from managed devices to reflect recent status of the network being managed. 2. When alerts are received, responses must be generated appropriate

Network Management Architectures (contd. ) 2) Managed Device • At each managed device, a special piece of software(process) called a management agent responds to polls for collected data, • 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

Registered Tree

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 • 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 format • 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

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 • 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)

Advantages of using SNMP • • • Standardized universally supported extendible portable allows distributed management access lightweight protocol