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