Fundamentals of Network Management In the Name of the Most High Fundamentals of Network Management by Behzad Akbari Fall 2011

Network Management Standards OSI Common Management Information Protocol (CMIP) International standard (ISO / OSI) Management of data comm. Network LAN and WAN Deals with all 7 layers Most complete Object oriented representation Well structured and layered Consumes large resources in implementation Internet Simple Network Management Protocol (SNMP) Industry standard (IETF) Originally intended for management of Internet components, currently adopted for WAN and telecom systems. Easy to implement Most widely implemented NM standard. Lacks advanced functionality (compared to CMIP)

Network Management Standards (…) Telecommunication Management Network (TMN) International standard of the ITU-T Management of telecom networks Based on the OSI network management framework Addresses both network, administrative, and business aspects of management. IEEE Addresses LAN and MAN management. Deals with the first 2 layers. Web-based Management Web-based Enterprise Management (WBEM) Java Management Application Program Interface (JMAPI)

Management Architecture This architecture is used for both OSI and SNMP-based management Consists of a number of models

OSI Models Organization Information Communication Functions Network management components Functions of components Relationships Information Structure of Management Information (SMI) Syntax and semantics Management Information Base (MIB) Organization of management information Communication Transfer syntax with bi-directional messages Transfer structure (PDU) Functions Application functions Configure components Monitor components Measure performance Secure information Usage accounting

SNMP Architecture and Models Organization Same as OSI model Information Same as OSI, but scalar Communication Messages less complex than OSI and unidirectional Transfer structure (PDU) Functions Application functions Operations Administration Security

Organizational Model Manager Agent Managed object Sends requests to agents Monitors alarms Houses applications Provides user interface Agent Gathers information from objects Configures parameters of objects Responds to managers’ requests Generates alarms and sends them to mangers Managed object Network element that is managed Houses management agent All objects are not managed / manageable

Organization Model Manage objects can be Managed object Network elements (hardware, system) hubs, bridges, routers, transmission facilities Software (non-physical) programs, algorithms Administrative information contact person, name of group of objects (IP group) Houses SNMP management agent Objects are classified into managed/unmanaged Managed object has a running management agent Manager Managed objects Unmanaged objects Two-Tier Network Management Organization Model Agent process MDB MDB Management Database

Organization Model Management Station (Manager) Interface for network managers to monitor and control the network Contains management applications (data analysis, fault recovery, etc.) Translation capabilities from manager’s requirements into actual monitoring and control of remote elements Contains DB of information extracted from MIBs of all the managed entities in the Network Manager Managed objects Unmanaged objects Two-Tier Network Management Organization Model Agent process MDB MDB Management Database

Organization Model Management Agent Gathers information from objects Configures parameters of objects (e.g., enable/disable a router port, shut down a port on a hub, etc.) Responds to requests for information and actions from managers Generates alarms and sends them to managers Manager Managed objects Unmanaged objects Two-Tier Network Management Organization Model Agent process MDB MDB Management Database

Organization Model Middle layer plays the dual role Agent to the top-level manager Manager to the managed objects collects, processes and stores data locally Performs statistical operation on the data and passes it to top level manager The intermediate system could be at a local site and passes info. to a remote site. Example of middle level: Remote monitoring agent (RMON) Agent / Manager Managed objects Agent process Manager Three-Tier Network Management Organization Model MDB MDB Management Database

Organization Model Different network domains, each managed locally MoM Agent Agent NMS Manager Managed objects MDB MoM Manager of Managers NMS Network Management System Different network domains, each managed locally Agent NMS manages the domain MoM presents integrated view of domains Domain may be geographical, administrative, vendor-specific products, etc.

Dual Role of Management Process Peer NMSs Dual Role of Management Process

Communication Model MIB MANAGER AGENT SNMP Resources are represented as objects (or data variables) Collection of objects is a MIB (more later) A manager performs monitoring by retrieving the value of MIB objects A manager causes an action to take place or changes the configuration settings by modifying values of specific variables

Communication Model MIB MANAGER AGENT SNMP Management stations and agents are linked by a network management protocol SNMP is used for the management of TCP/IP networks Get: manager or management station can retrieve the value of objects at the agent Set: set the values of objects at the agent Trap: agent notifies manager on significant events

Protocol Architecture -SNMP uses UDP port 161 - connection-less (e.g., Ethernet, X.25, ATM) Interprets SNMP messages and controls the agent’s MIB

Communication Model Management data is communicated between agent and manager as well as between managers Three aspects: Transport medium of message exchange (transport protocol) Message format (application protocol) Actual message (commands and responses) Manager Agent Operations / Requests Responses Notifications / Traps Applications Network Elements Managed Objects Management Message Communication Model

Management application Communication Model Management application Application manages object SNMP managed objects GetRequest GetNextRequest SetRequest GetResponse Trap Central MIB GetRequest GetNextRequest SetRequest GetResponse Trap Layer 1 & 2 IP SNMP Manager UDP SNMP Agent Network SNMP Messages

Trap-Directed Polling SNMP encourages the manager to use trap-directed polling A manager may be responsible for a large number agents, each maintains a large number of managed objects It is impractical to regularly poll all agents for all their readable objects (management overhead on the network may be very excessive!) managing entity agent data managing entity data managed device agent data network management protocol managed device agent data agent data managed device managed device

Trap-Directed Polling Initially a manager may poll all the agents for some key information e.g., interface characteristics (# pckts in/out, etc..) Then, each agent is responsible for notifying (through trap messages) the manager of any unusual event e.g., high pckt drop rate at some interface managing entity agent data managing entity data managed device agent data network management protocol managed device agent data agent data managed device managed device

Information Model The representation of objects and information relevant to their management This information is usually communicated between agents and management processes SMI (Structure of Management Information) defines the syntax and semantics of management information stored in MIB (Management Information Base) Example sysDescr: { system 1 } Syntax: OCTET STRING Definition: "A textual description of the entity. " Access: read-only Status: mandatory MIB Contains information about objects Organized by grouping of related objects Defines relationship between objects Agent MIB vs. Manager MIB MIB Agent: local information MIB Manager: info. on all network components

Information Model MDB physical database; e.g.. Oracle Contains measured or administratively configured values of NEs MIB virtual database; schema compiled into management software Info necessary for processes to exchange info. (e.g., #ports/hub) A NMS can automatically discover (periodic broadcast of PING messages) a managed object, such as a hub, when added to the network Once detected, its information (e.g., address, number of ports, etc.) is added to MDB MIB does not need to be updated if another hub from same vendor already exist

Management Information Tree Designation of objects: iso 1 org 1.3 dod 1.3.6 internet 1.3.6.1 Both Internet and OSI define objects uniquely by a tree structure Each managed object occupies a node in the tree underneath the root iso-itu 2 itu iso 1 org 3 dod 6 internet OSI Management Information Tree Root Level 1 Level 2 Level 3 Management Information Tree Standard organizations: define management of objects under them Managed Objects

Object Type and Instance Object ID and Descriptor circle Access: Access privilege Definition : Semantics - textual description Status Implementation requirements Syntax model of object Internet Perspective object ID unique ID and descriptor and name for the object syntax used to model the object access access privilege to a managed object (read-only, etc) status implementation requirements (e.g., optional or mandatory) definition textual description of the semantics of object type

Object Type and Instance Behavior Object Class: Circular object Elliptical Attributes: : circle, dimension Operations: Push ellipse, dimension Notifications Notify changes in attribute values OSI Perspective object class managed object attributes attributes visible at its boundary operations access operations that can be applied to it behavior behavior exhibited by it in response to an operation Notifications notifications emitted by the object

Object Type and Instance

Functional Model Configuration management Security management Set and change network configuration and component parameters Set up alarm thresholds Fault management Detection and isolation of failures in network Trouble ticket administration Performance management Monitor performance of network Security management Authentication Authorization Encryption Accounting management Functional accounting of network usage