Meraki Topology Showing Switches Hanging Incorrectly

[athan1234]

Hi 

I made a CPD migration, and now my customer is asking me why, in the Meraki topology, some switches appear to be hanging over other switches. In reality, all switches hang from Bbone-Core01.
When the customer checks the CDP neighbors, everything shows correctly — each switch hangs directly from Bbone-Core01 — but in the topology view, for example from 9200L-I-I-03, it shows additional switches hanging from it.

[alemabrahao]

Meraki tries to build a visual topology using Layer 2 discovery (CDP/LLDP) and some MAC/ARP intelligence.

If there are any inconsistencies in LLDP/CDP advertising or temporary learning mismatches during bootup/reconnection, it might infer wrong parent-child switch relationships.

[athan1234]

hi @alemabrahao 

Thank you for your response. I understand that Meraki uses Layer 2 discovery (CDP/LLDP) and MAC/ARP intelligence to build the topology, and that inconsistencies can cause wrong parent-child relationships.

However, I'm not entirely clear on what specific solution you're proposing. Could you please clarify:

1. How can I identify these LLDP/CDP inconsistencies? Is there a specific place in the Meraki dashboard where I can check for these issues?
2. What steps should I take to resolve the temporary learning mismatches? Should I restart the switches, or is there a way to force a topology refresh?
3. How long should I wait for the topology to self-correct? It's been [X time] since the migration, and the issue persists.

The customer is concerned because while CDP neighbors show correctly (all switches connected directly to Bbone-Core01), the visual topology still shows incorrect hierarchical relationships.

Any specific troubleshooting steps would be greatly appreciated.

Thanks again for your help!

[alemabrahao]

There's no manual "refresh" button in Meraki for the topology map. To be honest, you can't 100% trust what's displayed in this topology.

If you're still not confident, I suggest you open a support case.

[alemabrahao]

If the upstream core/aggregation switch in the network is not a Meraki MS switch and is capable of both CDP and LLDP, topology may not display correctly. To resolve this please disable CDP on the non-Meraki switch's interfaces to the MS switch or switch stacks. Once disabled, topology will slowly correct itself as the LLDP information is updated by each node. 

https://documentation.meraki.com/MS/Monitoring_and_Reporting/Network_Topology

[athan1234]

That explains exactly what's happening in my case. My Bbone-Core01 is a Cisco 9300 M switch that supports both CDP and LLDP, which is causing the topology display issues.

Based on the Meraki documentation you referenced, I now have a clear action plan. However, I have a couple of questions before implementing the solution:

Questions:

• Should I disable CDP globally on Bbone-Core01, or only on the specific interfaces connecting to Meraki switches?
• Approximately how long should I expect for the topology to correct itself after disabling CDP?

This makes perfect sense now - the conflicting CDP/LLDP information from the core switch was causing Meraki to infer incorrect parent-child relationships.

[athan1234]

That explains exactly what's happening in my case. My Bbone-Core01 is a Cisco 9300 M switch that supports both CDP and LLDP, which is causing the topology display issues.

Based on the Meraki documentation you referenced, I now have a clear action plan. However, I have a couple of questions before implementing the solution:

Questions:

• Should I disable CDP globally on the Cisco 9300 M, or only on the specific interfaces connecting to Meraki switches?

[alemabrahao]

I would disable it globally.