Question: Switch LEDs

certskills
By certskills April 21, 2015 09:05

The switch LEDs can tell you quite a bit of info about switch status. However, it’s sometime difficult to get the idea if you don’t have a real switch to experiment with, and press the status button on the front panel of the switch. Today’s sample question reviews some of those key points. The question is below the fold…

An engineer goes into a wiring closer to visit SW1, a Cisco 2960 switch. He notices that an LED labeled “3”, just above interface Fa0/3, has a nice, bright, green light that stays solid (it is not blinking). What current status information about this switch could the engineer learn from this LED?

A. Fa0/3 is in a connect state per the show interfaces status command

B. If the LED beside the SPEED button is green, Fa0/3 is running at 1000 Mbps (1 Gbps)

C. If the LED beside the STAT button is green, Fa0/3 is sending data at that instant in time

D. If the LED beside the STAT button is green, Fa0/3 is able to send and receive data, but is not sending data at that instant in time

.

 

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Answers to Monday's Switch LED Question
certskills
By certskills April 21, 2015 09:05
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March 18, 2011 6:47 am

[…] a link to the question. The answer is below the […]

dadash
dadash
April 21, 2015 3:03 pm

Hi Mr Odom, answer is “B” and “D”.

If the LED beside the SPEED button is flashing it’s mean port work at 100 mbps,
if green light stays solid than it’s working at 1000 mbps

If the LED beside the STAT button is green it’s mean port is not sending data at that instant time, if it’s flashing then port sending data at that instant time

OCC
OCC
April 21, 2015 11:42 pm

D only.

@dadash, B is not correct since when Speed Mode is selected, solid green above each interface Led indicates 100 mbps not 1000 mbps (flashing green).

Great material Mr. Odom. Thanks for it.

lyjo
lyjo
Admin
Reply to  OCC
April 22, 2015 6:13 am

You’re welcome, OCC.

Wagner Vieira
Wagner Vieira
April 22, 2015 12:01 am

Hi Mr. Odom,

Congratulations for your site. Really GOOD!

The correct answers if I need to choose two options is letters A and D.

Just to summarize:

B -> Incorrect, because a SPEDD port LED on 2960 switch to stay in 1Gbps MUST be in “Frashing/Blinking Green State” and not in “Solid Green State” like was referenced in the question. A “Solid Green State” for SPEED port LED on 2960 switch is a speed of 100Mbps and not 1Gbps like this letter says.

C -> Incorrect, because the LED is in “Green” but is in “Solid State” like was showed in the question, and a STAT port LED in “Solid Green State” on 2960 switch means that the port is working correctly and is already Up but there is no traffic passing over the interface.

So letters A and D is correct by theyselves according to all words in their sentences.

Regards,
Wagner Vieira.

Wagner Vieira
Wagner Vieira
April 22, 2015 12:25 am

Just to complete my explanation about letter C:

When a port is sending data traffic the “STAT port LED” MUST be in “Frashing/Blinking Green State” and not in “Solid Green State” like was showed in the question.

A port with the “STAT port LED” in “Frashing/Blinking Amber State” means that the port is blocked according to the Spanning-Tree Protocol convergence.

Best Regards,
Wagner Vieira.

lyjo
lyjo
Admin
April 22, 2015 6:12 am

Hi all,
thanks for the posts so far!
As usual, I’ll defer my own comments until the answers post, which should follow in a day or two. Thanks for playing!
Wendell

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