Term
| What is the purpose of monitoring? |
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Definition
| Evaluate network health and application performance |
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Term
| What does a network consist of? |
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Definition
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Term
| What (in detail) is the purpose of monitoring? |
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Definition
Check remote host availability
Determine topology
Evaluation traffic levels
Identify routing problems
OBserve path loadings
Investigate transport and application issues
Access server loading |
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Term
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Definition
Download speeds
Interaction
Reliability |
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Term
| What do you look at to eval network health? |
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Definition
Remote host availability
Topology
Traffic levels
ID routing problems
Observe path loadings
Investigate transport
Assess server loadings |
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Term
| Generically speaking, what does active monitoring involve? |
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Definition
probe packet / traffic
Receive response
Calculate parameters |
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Term
| What are the three advantages of active monitoring? |
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Definition
Simplicity
No guesswork
Extended to mac complex |
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Term
| What are the disadvantages of active monitoring? |
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Definition
Simplicity (Cannot accurately reproduce reality)
Cooperation
Differences |
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Term
| What is active monitoring good for? |
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Definition
Basic monitoring
Ideal for remote host availability
Good for estimating new characteristics
Fair for generalising network characteristics
Unless using improved / complex probing techniques |
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Term
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Definition
Less simplicity
Involves level of guesswork
No cooperation required
No control |
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Term
| What are the disadvantages of passive monitoring? |
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Definition
Difficult to correlate
Plenty of guesswork
No traffic: no results |
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Term
| Advantes of passive monitoring? |
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Definition
No traffic generated
Eval conditions for actual traffic
Good generalisation
Co-operation - not required |
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Term
| What is single-point network disadvantages? |
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Definition
Isolating problems to a specific sub-segment
ID one way problems
Routing flutter |
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Term
| What three places could you place single-point monitoring? |
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Definition
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Term
| What is single point monitoring good for? |
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Definition
End point/stub network
Single-path
Aggregated traffic transiting through a single location
Single-local-point-to-multiple-remote |
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Term
| Why would you distributed networking? |
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Definition
Defining network problems
Generating 'network health' reports |
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Term
| Distributed monitoring advantages? |
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Definition
Mesh internet weather reports
Eliminate fuzziness |
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Term
| Disadvantages of distributed monitoring? |
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Definition
Synchronisation
Access to multiple monitoring point |
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Term
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Definition
| Subset of tools aiming to describe the connectivity of nodes / networks |
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Term
| Example of topology measuremenet tool |
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Definition
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Term
| What do workload capture stuff do? |
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Definition
Perform analysis/ parsing
Does both overall and per-flow analysis |
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Term
| Are there a lot of performance monitoring tools? |
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Definition
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Term
| Are there a lot of routing tools? |
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Definition
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Term
| What's simplicity (Advantage of Active monitoring) |
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Definition
- Send / receive / calculate
- No need for specific positioning of the monitor |
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Term
| There's no guesswork required for active monitoring, but... |
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Definition
| It's difficult to segregate different causes from the result |
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Term
| What two complicated tasks can active monitoring potentially be expanded to perform? |
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Definition
Modelled probe traffic
Controlled probe traffic |
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Term
| What's modelled probe traffic? |
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Definition
| Burst, equally-spaced or pattern |
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Term
| What's controlled probe traffic? |
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Definition
| Full/ empty / malformed packets and headers |
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Term
| Why can simplicity (active monitoring) be a disadvantage? |
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Definition
| The probing mechanism may not accurately reproduce the reality |
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Term
| Why is cooperation a disadvantage of active monitoring? |
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Definition
| - Router drops the packet and the remote end doesn't respond |
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Term
| Why is differences a disadvantage for active monitoring? |
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Definition
| Certain network effects may appear only for specific traffic pattern |
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Term
| How does active monitoring estimate network characteristics? |
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Definition
| "It took 100ms for a response to come back therefore the delay for that exchange was..." |
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Term
| Why is passive monitoring less simplicity? |
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Definition
| A host with a bit of software is not enough, you need to tap the wire, listen & interpret |
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Term
| Why does passive monitoring involve a level of guesswork/ |
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Definition
| 'I received this, therefore that must have happened' |
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Term
| What three things might the number of monitoring points differentiate between? |
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Definition
- IDentifying vs Localising network problems
- Evaluation local network vs collections of networks
- Monitoring locally vs wide internetworking |
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Term
| What is distributed monitoring THE choice for? |
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Definition
- Defining network problems
- Generating network health reports |
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Term
| What does distributed network monitoring allow network managers to do? |
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Definition
| Locate the source of a problem |
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Term
| How does distributed monitoring partially eliminate guesswork from passive scenarios? |
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Definition
| By correlating events at both ends |
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Term
| What are the three monitoring scope classification? |
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Definition
Infrastructure
Traffic
Applications |
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Term
| What is infrastructure within monitoring scope classification? |
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Definition
Topology
Characteristics of the network
Geolocation |
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Term
| What is topology measurement? |
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Definition
| Aiming to describe the connectivity of nodes / networks |
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Term
| What does topology measurement rely on? |
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Definition
Either
Capturing / querying routing messages exchanged between core nodes
Discovering paths |
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Term
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Definition
| Packet capturing tools that perform analysis / parsing |
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Term
| What does workload aim to do? |
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Definition
| Define / describe the network traffic |
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