9300 Bug

taro75 · ‎06-26-2023

I have a Cisco 9300 switch with firmware "cat9k_iosxe.17.06.05.SPA"

I have the following configuration on port 1/0/6 which is connected to a laptop

interface GigabitEthernet1/0/6
switchport access vlan 101
switchport mode access
I am performing a continuous ping to this station from another server which works fine. Then I will disconnect the cable on 1/0/6 and connect back again, wait for 1 minutes for link to come up. Link comes up but ping is never successful. This is a strange behavior. The resolution was to add "spanning-tree portfast"

Is it a known bug on 9300 switch?

Flavio Miranda · ‎06-26-2023

Hi

Spanning-portfast is a good practice for Access port, no big deal here. Now, the interface come up and the ping never succeed this is not normal for sure.

When you say never you meant never or are you exaggerating?

taro75 · ‎06-26-2023

The laptop connected on 1/0/6 was not at all pinging, I just assigned a different IP address then it started pinging. But with spanning tree portfast this issue is not occurring.

hemmerling · ‎06-26-2023

I've seen this with printers and I usually chalk it up to the device gives up before the whole listening, learning process that can take up to 50 seconds (a lot longer it using 802.1x and waiting for it to timeout to hit the next method), adding portfast can speed this up and so the device gets the response in time.

Leo Laohoo · ‎06-26-2023

@taro75 wrote:
wait for 1 minutes for link to come up.

STP takes 55 seconds to cycle through the stages until it reaches FORWARDING. This is not a "bug" but a regular behaviour of STP.

taro75 · ‎06-28-2023

My issue is that even after 1 minutes the PC is not able to ping.

Leo Laohoo · ‎06-28-2023

@taro75 wrote:
The resolution was to add "spanning-tree portfast"

You are not making sense.

If it issue is not fixed then what do you mean "The resolution was to add "spanning-tree portfast"?

rasmus.elmholt · ‎06-28-2023

To me it seems like you have a silent host problem.

sometimes we see this as well, because the interface on the host is up, but it cannot send any packets caused by STP listening/learning mode for up to a minute, and then the host IP stack is not starting up as expected.