Topic 11 Network Management

SNMPv1 This information is specific to SNMPv1. When using SNMPv1, the snmpd agent uses a simple authentication scheme to determine which Simple Network Management Protocol (SNMP) manager stations can access its Management Information Base (MIB) variables.

Simple Network Management Protocol (SNMP ) is the protocol developed to manage nodes (servers, workstations, routers, switches and hubs etc.) on an IP network. SNMP is an application protocol, which is encapsulated in UDP. Currently, there are three versions of SNMP defined: SNMP v1, SNMP v2 and SNMP v3SNMP UDP SNMPSNMP v2SNMP v3

In typical SNMP uses, one or more administrative computers, called managers, have the task of monitoring or managing a group of hosts or devices on a computer network. Each managed system executes, at all times, a software component called an agent which reports information via SNMP to the manager.computer network

Essentially, SNMP agents expose management data on the managed systems as variables. The protocol also permits active management tasks, such as modifying and applying a new configuration through remote modification of these variables. The variables accessible via SNMP are organized in hierarchies. These hierarchies, and other metadata (such as type and description of the variable), are described by Management Information Bases (MIBs).Management Information Bases

An SNMP-managed network consists of three key components: Managed device Agent — software which runs on managed devices Network management system (NMS) — software which runs on the manager

A managed device is a network node that implements an SNMP interface that allows unidirectional (read-only) or bidirectional access to node-specific information. Managed devices exchange node-specific information with the NMSs. Sometimes called network elements, the managed devices can be any type of device, including, but not limited to, routers, access servers, switches, bridges, hubs, IP telephones, IP video cameras, computer hosts, and printers.routersaccess serversswitchesbridgeshubsIP telephonesIP video camerashostsprinters

An agent is a network-management software module that resides on a managed device. An agent has local knowledge of management information and translates that information to or from an SNMP specific form.

A network management system (NMS) executes applications that monitor and control managed devices. NMSs provide the bulk of the processing and memory resources required for network management. One or more NMSs may exist on any managed network.network management system

SNMP version 1 (SNMPv1) is the initial implementation of the SNMP protocol. SNMPv1 operates over protocols such as User Datagram Protocol (UDP), Internet Protocol (IP), OSI Connectionless Network Service (CLNS), AppleTalk Datagram-Delivery Protocol (DDP), and Novell Internet Packet Exchange (IPX). SNMPv1 is widely used.

SNMPv1 & SNMPv2c interoperability As presently specified, SNMPv2c is incompatible with SNMPv1 in two key areas: message formats and protocol operations. SNMPv2c messages use different header and protocol data unit (PDU) formats from SNMPv1 messages. SNMPv2c also uses two protocol operations that are not specified in SNMPv1.

Although SNMPv3 makes no changes to the protocol aside from the addition of cryptographic security, it looks much different due to new textual conventions, concepts, and terminology. SNMPv3 primarily added security and remote configuration enhancements to SNMP.

Overview of SNMP Versions SNMPv1 was the standard version of SNMP. The SNMPv2 was created as an update of SNMPv1 with several features. The key enhancements of SNMPv2 are focused on the SMI, Manager-to- manager capability, and protocol operations. The SNMPv2c combined the community-based approach of SNMPv1 with the protocol operation of SNMPv2 and omitted all SNMPv2 security features. One notable deficiency in SNMP was the difficulty in monitoring networks, as opposed to nodes on networks. A substantial functional enhancement to SNMP was achieved by the definition of a set of standardized management objects referred to as the Remote Network Monitoring MIB (RMON MIB) objects. Another major deficiency in SNMP was the complete lack of security facilities. The development of SNMPv3 was based on the security issues. SNMPv3 defines two security-related capabilities, namely USM and VACM.

Internet Engineering Task Force (IETF) publishes documents that are called Requests For Comments (RFCs). These documents specify standards, operational practices, opinions, etc. for the Internet protocol suite.

SNMPv1: This is the first version of the protocol, which is defined in RFCs 1155 and SNMPv2c: This is the revised protocol, which includes enhancements of SNMPv1 in the areas of protocol packet types, transport mappings, MIB structure elements but using the existing SNMPv1 administration structure ("community based" and hence SNMPv2c). It is defined in RFC 1901, RFC 1905, RFC 1906, RFC2578.

SNMPv3: SNMPv3 defines the secure version of the SNMP. SNMPv3 also facilitates remote configuration of the SNMP entities. It is defined by RFC 1905, RFC 1906, RFC 3411, RFC 3412, RFC 3414, RFC 3415.

RMON The Remote Network MONitoring (RMON) MIB was developed by the IETF to support monitoring and protocol analysis of LANs. The original version (sometimes referred to as RMON1) focused on OSI Layer 1 and Layer 2 information in Ethernet and Token Ring networks. MIBIETFLANsOSI Layer 1Layer 2

An RMON implementation typically operates in a client/server model. Monitoring devices (commonly called "probes" in this context) contain RMON software agents that collect information and analyze packets.

These probes act as servers and the Network Management applications that communicate with them act as clients. While both agent configuration and data collection use SNMP, RMON is designed to operate differently than other SNMP-based systems:SNMP

Probes have more responsibility for data collection and processing, which reduces SNMP traffic and the processing load of the clients. Information is only transmitted to the management application when required, instead of continuous polling.

CMIP The Common Management Information Protocol (CMIP) is the OSI specified network management protocol.network management

Common Management Information Protocol (CMIP) is a network management protocol built on the Open Systems Interconnection (OSI) communication model. The related Common Management Information Services (CMIS) defines services for accessing information about network objects or devices, controlling them, and receiving status reports from them.OSI

CMIS is a service employed by network elements to manage networks; and it defines how the service interfaces with network elements. Implementing that interface is done by the CMIP. The two terms are sometimes erroneously interchanged, e.g. CMIP used when CMIS is meant.

Common Management Information Protocol was originally designed as a replacement for SNMP, which is less sophisticated with far fewer features, but more widely adopted. For example, CMIP allows the definition of any type of action; whereas SNMP defines only a limited number of actions to alter the state of a managed device.

It has been extended by RMON2 which adds support for Network- and Application-layer monitoring and by SMON which adds support for switched networks. It is an industry standard specification that provides much of the functionality offered by proprietary network analyzers. RMON agents are built into many high-end switches and routers.Network-Application-layerSMON

Remote Monitoring (RMON) is a standard monitoring specification that enables various network monitors and console systems to exchange network-monitoring data. RMON provides network administrators with more freedom in selecting network-monitoring probes and consoles with features that meet their particular networking needs.