Client shows connected to MS switch but shouldnt

[PacerX]

Hello everyone,

I have a Cisco 2960-S plugged directly into an MX100 however the Laptop I have connected to the 2960-S is showing that it is connected to one of our MS250 units. I understand that the 2960-S wouldn't show up in the switch list however I would think that at least it would show the laptop connected to the MX100. Any idea why this would be? 

Just trying to understand how this dashboard reporting would work.

Thanks in advanced.

[KarstenI]

Yes, although the Catalyst is not visible in the dashboard, the client shouldn't show up "somewhere else". Sadly, the moment a client is connected to an MX directly or through a third party device, this dashboard-feature gets completely screwed up. A couple of clients had support cases open for this but nothing turned out there. I think it's not a Meraki priority to fix this.

[PacerX]

@KarstenI Thanks for the confirmation.

[RaphaelL]

Pretty sure you have to ask Meraki support to disable  'sample clients on uplink' to fix this.

[KarstenI]

Hmm, never heard of this option … Now additional questions come up:

1. what is the drawback of this option?
2. Why is it not default?
3. Why has support never mentioned it?

[RaphaelL]

This mostly happens when the Meraki devices are splitted in 2 networks OR you have Non-Meraki devices in the mix : 

If Client A sends a ARP or any broadcast , it will reach both switches. Switch on the left 'may' sample the packets from client 'A' and update the client list with Client 'A's MAC on the uplink which 100% causes confusion because you lose track of where the client is actually coming from.

It is not by default because Meraki assumes that all devices are Meraki. The major drawback is that it is hidden and per-network and not org-wide. I'm pretty sure that you have to open a ticket to support everytime you create a new network from scratch ( a.k.a not cloned from that said network or from a template that already have that feature on ).

I'm not sure if someone from Meraki can affirm that or not , but this is what we were told this year.

Our distribution switches are Cat 6816 and this ''issue'' happens for clients that are seen on vlans that are spanned to multiple stacks on the same network. Most of our vlans are unique per stacks ( per floor ) so we don't often get that situation , but you know there is always an exception in every network 😒

EDIT : it is not often discussed but I found some post about it : https://community.meraki.com/t5/Dashboard-Administration/Clients-from-Other-Network-Showing-in-Dashb...  https://community.meraki.com/t5/Switching/Clients-on-Uplinks/m-p/31989 

[KarstenI]

Good to know about this feature!

For me, I have seen this behavior also in pure Meraki networks. Have to think about it if it would improve something.

[RaphaelL]

A completed and detailed list of ALL backend options would be soooooo nice to have !

[KarstenI]

BTW: Most of the time it is easy to spot like my AppleTV that in fact is directly connected to the MX:

Always when the uplink- and downlink-port on the L2-switch is the same, it's not shown as it's really connected.