Multiple Port RSTP role change on switches

[Roey1984]

Hello

We have a site with Cisco Meraki equipment (MX 67 + MS120-48LP)

I see many events in the Event Log for the switch (Port RSTP role change)

*Attached picture.

Users are complaining that Download\Upload speeds are very low.

Moreover, I can see in the Event log for the security appliance many Events dropped (Pic attached)

For the switches, the "STP configuration" is Enabled (Pic attached) 

Any idea how to start the diagnosis?

[alemabrahao]

Check it out:

Spanning Tree Protocol (STP)

The MX does not run STP in any capacity, and will not exchange BPDUs with other switches or participate in the root bridge election process. If the MX received BPDUs on the LAN, these BPDUs will be re-forwarded within the broadcast domain that they were received on. If there are multiple switches connected to the LAN of the MX participating in an STP election, all BPDUs sent to the MX will be forwarded to other links with the same VLAN allowed, which can cause switches to see BPDUs from multiple other switches, causing ports to get into an unknown/unidentifiable state and impacting the root bridge election process.

Below is a diagram illustrating how the STP election process can be affected by this MX LAN forwarding behavior - when 3+ switches are connected in the same broadcast domain, each switch will receive BPDUs from 2 or more switches on their connected uplinks. In the case of switches 2 and 3, the uplink is both a root port and a designated port from the switches' perspectives, causing the ports to go into an unknown state. In practice, this can also result in rapid STP port status changes for uplinks on multiple switches.

https://documentation.meraki.com/MX/Networks_and_Routing/MX_Layer_2_Functionality

[alemabrahao]

Looks like a layer 1 problem, by the way, I suggest you check the cables or even test on another switch or MX port.

[Roey1984]

Hey @alemabrahao 

Thank you for responding!

We only have one switch in this network.

So you think it`s a matter of cables?

Should I run the Cable rest on the switch? (I`m working remotely, but can do it now, no one is working in that office now)

[alemabrahao]

Yes, there is a possibility, although I like the cable test function, I don't trust it 100%, I find it more interesting to configure another physical port and test it, in addition to testing with another cable.

Another thing I've noticed is that STP is changing on ports 3 and 13, what exactly is plugged into those ports?

[Roey1984]

I have no one who can get another switch there and test with another cable (At least not in the upcoming week)

So maybe I`ll start with the Cable Test from the Dashboard.

Regarding the STP change on those ports, Port 3 - is a PS5 (Console) - currently turned off.

Port 13- Is a Lenovo Workstation - is currently up and running, but it seems like its port speed is 10Mbps - Dont know why; maybe a local issue with this Workstation.

[alemabrahao]

It makes sense that the speed is slow if the port is negotiating at 10Mbps. So this could be a problem with the cable or the network card itself.

Do you have any traffic shaping rules applied?

[Roey1984]

I ran the Cable test on the ports.

The 10Mbps port cable seems damaged; I`ll have the user replace it!

Regarding the traffic shaping rules, we have a "Per-client limit' for 50Mbps, & "SpeedBurst " is enabled  (I was advised to keep it on, What do you think?)

Moreover, we have the following rule applied: ( VOIP traffic priority set to High) 

[alemabrahao]

I believe that by changing the cable your problem should be solved and 50Mbps seems to me to be a good number, of course it has to take into account the amount of traffic that is generated on your network, but it seems good to me.

[Roey1984]

Great!

I`ll have the user replace the cable tomorrow.

I tried to Cycle this specific port, but again it is still 10Mbps, + the Cable test is not ok.

I can see this port goes up and down all the time - Should I disable it for now? or better yet, change the RSTP to Disabled until the user replaces the cable?

[Roey1984]

BTW

I have another site, that has Two MS120 switches there. (This is the site I work at and have physical access to the equipment)

I can see there also many RSTP role change for multiple ports (One of them I see the cable is not good, and I`ll have it replaced tomorrow)

But for the rest of the ports with the RSTP role change, the cables are ok (According to the test from the dashboard).

Do you recommend replacing them either way (since U said I should count on the cable test from the Dashboard).  - it is a VOIP equipment (Logitech MeetUp).

[RaphaelL]

All these events of ports going up and down could be simply that the machine is going into a sleep/eco mode. 

Like alemabrahao said , that could also be a layer1 issue with your cabling.

[ww]

That many dropped events on your mx does not look good. What firmware are you running? What is the utilization of that mx. https://documentation.meraki.com/MX/Monitoring_and_Reporting/Device_Utilization

[Roey1984]

I agree

The Current (MX67) version is: MX 18.107.2

The utilization is as follows  (Currently, the users are not working, all are at home) - and overall it seems that it`s very low

What do you recommend?

[ww]

Summary looks fine. If your problems started after a firmware upgrade you could try downgrade.  Or create a meraki support case to figure out what the cause  of the dropped events is