Translated:
Hello,
I work for a School District. Each of our schools has at least two wiring closets (mdf & idf). The primary closet (MDF) is connected directly to a Cisco Catalyst 9500 for internet access, with the 9500 being the root switch for STP.
Each closet has several Meraki ms225, connected to each other through a stack of switches. At the same time, each closet connects to the MDF and the latter to the 9500.
On the 9500 port, towards the MDF, I have "Root Guard" configured to prevent one of the Meraki from becoming a root bridge. What would be the port configurations for each of the connections from each idf to the mdf?
I want to know if Root Guard also applies or if I have to declare it Loop Guard?
Thank you,
---
Response:
Hola Domntr05!
Hay un documento bastante completo que detalla el caso de uso para cada una de las opciones de protección STP, vinculado aquí: https://documentation.meraki.com/MS/Port_and_VLAN_Configuration/Configuring_Spanning_Tree_on_Meraki_...
Como breve explicación:
Root guard generalmente se aplica a los puertos que se encuentran frente a los conmutadores descendentes que están más cerca de los dispositivos cliente en la topología de la red. Evita que esos conmutadores inferiores se conviertan en la raíz STP al evitar que pasen mensajes BPDU superiores.
Loop Guard se utiliza para evitar que se produzcan bucles en la topología STP, cuando parte de un enlace falla y se vuelve unidireccional. Esto se aplica más comúnmente para conexiones de fibra óptica, ya que un cable se usa para transmitir datos y el otro cable para recibir datos.
En su caso, si no tiene cables de fibra óptica que conecten el IDF y el MDF, no necesitará configurar ninguna función de protección en los conmutadores descendentes. Si está utilizando cables de fibra para conectar el MDF y el IDF, entonces debe agregar Loop Guard a los puertos que se conectan desde el MS and upstream.
---
Translated response:
Hi Domntr05!
There is a quite comprehensive document that details the use-case for each of the STP guard options, linked here: https://documentation.meraki.com/MS/Port_and_VLAN_Configuration/Configuring_Spanning_Tree_on_Meraki_...
As a short explanation:
Root guard is usually applied to ports that face switches downstream who are closer to the client devices in the network topology. It stops those lower down switches from becoming the STP root by preventing them from passing any superior BPDU messages onwards.
Loop Guard is used to stop loops from occurring in the STP topology, when part of a link fails and becomes unidirectional. This is more commonly applied for fiber optic connections, as one cable is used to transmit data and one cable is used to receive data.
In your case, if you do not have fiber optic cables connecting the IDF and MDF, then you would not need to configure any guard functionality on the downstream switches. If you are using fiber cables to connect the MDF and IDF, then you should add Loop guard to the ports which connect from the MS to the upstream.
