1Network Management 1School of BusinessEastern Illinois University © Abdou Illia, Spring 2006(Week 15, Friday 4/21/2006)(Week 16, Monday 4/24/2006)2Learning Objectives Generating Useful Statistics– Availability– Reliability Centralized Network Management3Generating Useful Statistics Statistics: Data about network operation or network devices operation Example: Availability of a modem, Reliability of a Hub, transmission speed, etc. Statistics are very helpful for network management– Could help identifying problems in Network operation– Could be used to demonstrate the need to invest in technologyQ: What kind of tools, already introduced in class, can be used to generate useful statistics?24Availability Availability: probability that a particular component or system will be available during a fixed time period Availability is function of:– Mean time between failures (Given by manufacturer or generated based on past performance)– Mean time to repair (Found in studies or in our archives) Mean time between failures (MTBF) is the average time a device or system will operate before it fails. Mean time to repair (MTTR) is the average time necessary to repair a failure5 Standard equation:A(t) = a/(a+b) + b/(a+b) x e-(a+b)tin which: a = 1/MTTRb = 1/MTBFe = natural log functiont = the time interval Approximation equation:Availability% = (Total available time – Downtime)/Total available timeAvailability6Suppose we want to calculate the availability of a modem that has a MTBF of 3000 hours and a MTTR of 1 hour. The availability of this modem for an 8-hour period is:a = 1/1b = 1/3000 = 0.00033A(8 hours) =1/(1 + 0.00033) + 0.00033/(1 + 0.00033) x e-(1 + 0.00033)8= 0.9997 + 0.00033 x 0.000335= 0.9997AvailabilityQ: What will be the availability of the modem if the Approximation equation is used?A(t) = a/(a+b) + b/(a+b) x e-(a+b)t37Availability A component has been operating continuously for three months. During that time, it has failed twice, resulting in downtime of 4.5 hours. Calculate the availability of the component during that three-month period using the Approximation method.8Availability To calculate the availability of a system of components:– Calculate the availability of each component– Find the product of all availabilities Example: If a network has tree devices with availabilities of 0.992, 0.894, and 0.999, the availability of the network is:0.992 x 0.894 x 0.999 = 0.8869Reliability Reliability: probability that a component or system will be operational for the duration of a transaction time t.  Reliability is function of:– Mean time between failures– Transaction time Mean time between failures (MTBF) is the average time a device or system will operate before it fails. Transaction time is the time interval of operation to complete a given transaction.410ReliabilityReliability is defined by the equation:R(t) = e-btin which: b = 1/MTBFt = the time interval of the operation11ReliabilityWhat is the reliability of a modem if the MTBF is 3000 hours and a transaction takes 20 minutes, or 1/3 of an hour (0.333 hours):R(t) = e-btb = 1/MTBF = 1/3000t = 0.333R(0.333 hours) = e -(1/3000)(0.333)= e -0.000111= 0.99989Q: If a component has a MTBF of 500 hours and a transaction takes 4 seconds, calculate the reliability of the component 12Summary QuestionsSee slides # 6, 7, 115Network Management 2School of BusinessEastern Illinois University © Abdou Illia, Spring 200614Learning Objectives List main elements in Centralized network management Describe Centralized Network Management principles Describe Manager-Agent communications15Centralized network management ? Remotely managing a network from a central point (for example a PC) :– Gathering data about network performance– Fine-tuning network performance– Diagnosing problems– Fixing problems– Controlling security– Etc. Centralized network management is possible with:– Managed networking components, and– Communication systems based on Network management protocols616Managed networking component ? Managed Networking components– Have objects that can be managed remotely– Include software components that gather data about their operation. Managed networking components can be printers, hubs, switches, routers, application programs, etc. Managed SwitchObjectPropertyPort 1Port 2Port 3ValueStatusStatusStatusOnOnOffSoftware components inside17Centralized network managementNetwork ManagementSoftware (Manager)RMON device The Manager (an application program) is used to communicate with managed components. The RMON is a stand-alone device or a software running in a switch or a router The RMON collects data on network trafficSwitch* RMON = Remote Monitoring18Centralized network managementNetwork ManagementSoftware (Manager)NetworkManagementAgent (Agent)RMON deviceNetworkManagementAgent (Agent) The Agents (software programs) acts on behalf of managed device The Manager doesn’t communicate with the managed device, but rather with its Agent719Centralized network managementManagementInformationBase (MIB)ManagementInformationBase (MIB)ManagementInformationBase (MIB)Network ManagementSoftware (Manager)RMON device The MIB is a data base on objects and their characteristics (properties, etc.)  There is a small MIB on managed deviceThere is a complete MIB on the manager’s computer.20Centralized network managementManagementInformationBase (MIB)ManagementInformationBase (MIB)ManagementInformationBase (MIB)Network ManagementSoftware (Manager)Simple NetworkManagement Protocol (SNMP)RMON deviceCommand (Get, Set)ResponseTrap21Summary Questions (1)1) List the main elements in centralized network management 2) Does the Manager communicate directly with the managed devices? Explain.3) Explain the difference between a managed device and objects.4) Where is the MIB (database) stored?822Manager-Agent communicationsNetworkManagementAgent (Agent)Network ManagementSoftware (Manager)Simple NetworkManagement Protocol (SNMP) Communication between the Manager and Agents works through command-response cycles The Manager sends a command The Agent sends back a response23Manager-Agent communicationsNetworkManagementAgent (Agent)Network ManagementSoftware (Manager)Get commands tell the Agent to retrieve certain information and return this information to the Manager.Example: Get status of port 1 and 2 on the switchSet commands tell