C9300-48UXM Port LED Behaviour

[nooriik]

I have a C9300-48UXM originally running 17.6.5 now 17.9.4a (symptom present on both code versions) on the bench, is it normal for the port status LEDs to flash continuously (green) even when there is next to no traffic on the port?

A single device connected, running wireshark, default config, with only STP packets being sent out on the port  (approx 1 per second) and the LED is blinking like it's going full chat. Enabling bpdufilter to stop the STP packets, the lack of any packets at all allows the LED to stop flashing. Essentially a single packet causes the port LED to flash very fast (green) for ~4 seconds.

When devices are connected the activity LEDs make it look like it's storming even though traffic is totally normal and the LEDs on the plugged in devices behave as you would expect, appears to be no issue with network performance, and no issue at all with the cpu usage on it.

Is this normal? Having only used 48Ps in production which I haven't seen do this, I don't know if it's an issue or normal behaviour for the 48UXMs.

[marce1000]

                 - Usually in modern switches the blinking rate no longer indicates traffic rate(s)  : https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9300/hardware/install/b_c9300_hig/b_c9300_hig_chapter_01001.html
>....

Table 12. Meaning of Switch LED Colors in Different Modes

Port Mode	Port LED Color	Meaning
STAT (port status)	Off	No link, or port was administratively shut down.
	Green	Link present, no activity.
	Blinking green	Activity. Port is sending or receiving data.
	Alternating green-amber	Link fault. Error frames can affect connectivity, and errors such as excessive collisions, CRC errors, and alignment and jabber errors are monitored for a link-fault indication.
	Amber	Port is blocked by Spanning Tree Protocol (STP) and is not forwarding data. After a port is reconfigured, the port LED can be amber for up to 30 seconds as STP checks the switch for possible loops.

[gopherknee2020]

I am assisting with troubleshooting a 9300 that is used a core switch to a cisco 250 using Fiber. We are using Axiom Fiber LC/LC Transceivers on both ends. The link comes up the light starts to flash slow like its working but we cannot get to the switch config UI. if we connect ethernet switch to switch we can. The Light on the SFP port on both ends is flashing slow green twice then solid green for about 2 seconds. It repeats.  I cannot find a chart of what the blinking lights means.. We tried Fiber mall transceivers as well with the same result. Any ideas?

[Leo Laohoo]

Post the complete output to the command "sh interface <FIBRE PORT>" from both sides.

[MHM Cisco World]

Do you config any 802.1x?

MHM

[nooriik]

@marce1000 Sure, it just puzzled me as a 48P next to it manufactured the same month behaves differently that's all. It does appear to be cosmetic only but still wondered if anyone else who uses 48UXMs regularly sees this as normal behaviour.

@MHM Cisco World This was tested on a completely factory config

[MHM Cisco World]

Port is support poe

MHM

[Leo Laohoo]

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@nooriik wrote:
even when there is next to no traffic on the port?

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Regardless if the downstream client is not talking or not, there will always be outbound (switch to downstream client) traffic.  

[adventurer]

I'm observing the same port led fast blink on a 9300UN. Same observation as the first poster, I'm comparing with a 9300U and this 9300UN definitely led blink a lot faster, like having a network storm.

This is my first play with multigig switch, wondering did someone forgot to update the LED colors/blink table.