Spanning-Tree LED light color on Nexus & Catalyst switches

[HuyDC]

Hello you all,

Please kindly help me answer my question

My system using Nexus 9508 for A building core devices and Catalyst 4500 for B building core devices

All my L2 switches is Catalyst 2960 are connecting to core devices but

All devices which connecting with Nexus 9508 have uplink LED light color is Green & Amber

Uplink configuration:

interface GigabitEthernet0/1 & 2
 switchport access vlan X
 switchport mode access

All devices which connecting with Catalyst 4500 have uplink LED light color is only Green

Uplink configuration:

interface GigabitEthernet0/1
 switchport trunk allowed vlan Y
 switchport mode trunk
 udld port aggressive

Even thought the status on all uplink are same, Gi0/1 is Root port, Gi0/2 is Alternate Blocking port

So I am wondering what make this difference, if just looking at L2 switches how can I know that Spanning-Tree is working normally without show running config.

Thank you all so much for any information

[Reza Sharifi]

Hi,

Even thought the status on all uplink are same, Gi0/1 is Root port, Gi0/2 is Alternate Blocking port

If gi0/2 is amber on all switches, that is most likely because that the STP blocking port. See this document and see table-1-6 for explanation.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/hardware/installation/guide/3750hig/HIGOVERV.html#wp1136573

HTH

[HuyDC]

Hello bro,

I know that, but my question here is why on Catalys 4500 the all Gi0/2 are blocked by STP but the LED still is Green, not Amber ?

On Nexus 9500 series all Gi0/2 port are normally, I mean the LED are Amber as usual

[HuyDC]

@Reza Sharifi Could you please answer my question. Thanks you !

[Sergiu.Daniluk]

Hi @HuyDC 

You can refer to this table for port LED color meaning:

Cat 4500: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/hardware/installation/guide/78-14409-08/4500inst/01intro.html#wpxref69261 

Nexus: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/hw/n93128_hig/guide/b_n93128_hardware_install_guide/b_n93128_hardware_install_guide_appendix_01000.html 

As you can see, on Cat 4500, there is no mention of STP for the coloring. If port is operational up, then Port LED is green, regardless of STP state.

Hope it helps,

Sergiu