5.4 Given a scenario, troubleshoot common performance issues.

Question 1

If the network can only handle one gigabit per second what happens when there are multiple links that each sending traffic of one gigabit per second? What is this called?

Answer 1

• This is known as Congestion/contention
• Buffers will fill and some data may be dropped.

Question 2

Bottlenecking

Answer 2

• The problem could be related to a number of different performance metrics/parameters.
• You need to monitor all of them to find the slowest one.

Question 3

Bandwidth (throughput capacity)

Answer 3

• How much a network is being used over a certain amount of time.

Question 4

Latency

Answer 4

• the delay between the request and the response. (Waiting time)
• Some is expected and normal
• Examine the response times at every step along the way.

Question 5

Packet Loss

Answer 5

• No errors in the packet, but system could not transmit or receive the data.

Question 6

Jitter

Answer 6

• It is the time between frames
• Typically used when referencing VoIP
• Excessive amounts of this can cause you to miss information, “choppy” voice calls.

Question 7

What are 5 common wireless networking issues?

Answer 7

1. Interference (channel overlap)
2. Signal degradation (attenuation)
3. Insufficient wireless coverage
4. Client disassociation issues
5. Roaming misconfiguration

Question 8

Throughput

Answer 8

The amount of data successfully transferred through the network.

Question 9

Interference as a wireless networking issue.

Answer 9

• Limited amount of frequency (everyone can’t talk at the same time).
• Increasing number of wireless devices.
• Most AP can monitor frequency usage and automatically move to an used space.
• Disable legacy, low speed support
• Avoid overlap between access points (turn on automatic function).

Question 10

Signal degradation as a wireless networking issue.

Answer 10

• Signals get weaker as you move farther away from the antenna.
• Can be measured with a Wi-Fi analyzer.
• Control the power output on the access point.
• Use a receive antenna with a higher gain.
• Some power is lost in the antenna cable coax.

Question 11

Insufficient coverage as a wireless networking issue.

Answer 11

• Determine the existing wireless landscape.
• Identify existing access points.
• Work around existing frequencies.
• Heat maps

Question 12

Client disassociation as a wireless networking issue.

Answer 12

• An older networking issue.
• Takes advantage of older 802.11 management frame transmission.
• Your device(s) keeps dropping from the wireless network (or never connects).
• Disassociation frames can be clearly seen in a packet capture using Wireshark.

Question 13

Roaming misconfiguration as a wireless networking issue.

Answer 13

• A wireless network often has a single name (SSID)
• There might be multiple access points supporting SSID
• These access points must have identical configurations and users will be dropped if configurations differ.