1. Network Management 1 School of Business Eastern Illinois University Abdou Illia, Spring 2006 (Week 15, Friday 4/21/2006) (Week 16, Monday 4/24/2006)

2. Learning Objectives

Generating Useful Statistics

• Availability

• Reliability

Centralized Network Management

3. Generating 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 technology

Q: What kind of tools, already introduced in class, can be used to generate useful statistics? 4. Availability

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 failure

5.

Standard equation:

A( t ) = a/(a+b) + b/(a+b) x e -(a+b)t

in which: a= 1/MTTR

b= 1/MTBF

e= natural log function

t= the time interval

Approximation equation:

Availability% = (Total available time Downtime)/Total available time

Availability 6. Suppose 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 = 1/1 b = 1/3000 = 0.00033 A(8 hours) =1/(1 + 0.00033) + 0.00033/(1 + 0.00033) x e -(1 + 0.00033)8 =0.9997 + 0.00033 x 0.000335 =0.9997 Availability Q: 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)t 7. Availability

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.

8. Availability

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 = 0.886

9. Reliability

Reliability: probability that a component or system will be operational for the duration of a transaction timet .

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 timeis the time interval of operation to complete a given transaction.

10. Reliability

Reliabilityis defined by the equation:

• • R( t ) =e - bt

in which: b= 1/MTBF

t= the time interval of the operation

11. Reliability What 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 - bt b= 1/MTBF = 1/3000 t= 0.333 R(0.333 hours) = e-(1/3000)(0.333)= e-0.000111= 0.99989 Q: If a component has a MTBF of 500 hours and a transaction takes 4 seconds, calculate the reliability of the component 12. Summary Questions

See slides # 6, 7, 11

13. Network Management 2 School of Business Eastern Illinois University Abdou Illia, Spring 2006 14. Learning Objectives

List main elements in Centralized network management

Describe Centralized Network Management principles

Describe Manager-Agent communications

15. Centralized 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 protocols

16. Managed 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 Switch Object Property Port 1 Port 2 Port 3 Value Status Status Status On On Off Software components inside 17. Centralized network management Network Management Software (Manager) RMON device

The Manager (an applicationprogram) 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 traffic

Switch * RMON = Remote Monitoring 18. Centralized network management Network Management Software (Manager) Network Management Agent (Agent) RMON device Network Management Agent (Agent)

The Agents (softwareprograms) acts on behalf of managed device

The Manager doesnt communicate with the managed device, but rather with its Agent

19. Centralized network management Management Information Base (MIB) Management Information Base (MIB) Management Information Base (MIB) Network Management Software (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 managers computer.

20. Centralized network management Management Information Base (MIB) Management Information Base (MIB) Management Information Base (MIB) Network Management Software (Manager) Simple Network Management Protocol (SNMP) RMON device Command (Get, Set) Response Trap 21. Summary Questions (1)

List the main elements in centralized network management

Does the Manager communicate directly with the managed devices? Explain.

Explain the difference between a managed device and objects.

Where is the MIB (database) stored?

22. Manager-Agent communications Network Management Agent (Agent) Network Management Software (Manager) Simple Network Management Protocol (SNMP)

Communication between the Manager and Agents works through command-response cycles

The Manager sends a command

The Agent sends back a response

23. Manager-Agent communications Network Management Agent (Agent) Network Management Software (Manager)

Getcommands 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

Setcommands tell the Agent to set a parameter (a property of an object) on the managed device. Example: Set the status of Port 2 on the switch to off.

Command ( Get ,Set ) 24. Manager-Agent communications Network Management Agent (Agent) Network Management Software (Manager)

Sometimes Agents do not wait for commands to send information

If the Agent detects a condition the Manager should know about, it can send a Trap message to the Manager

Trap 25. Summary Questions (2)

In Manager-Agent communications, which device creates commands? Responses? Traps?

Explain the two types of commands.

What is a trap?