Source IP and/or VLAN mismatch, Internet connection issues

[tantony]

I noticed that we're getting Source IP and/or VLAN mismatch on the event log.  Since then, our internet connection have been going offline.

I found out that we had a switch on the wrong sub net of 192.168.0.x, but the Meraki sub nets are on 172.16.0.x.  Since changing the switch to the Meraki sub net it looks like the connection improved.  But, according to Meraki, there's still another switch on the 192.168.0.x subnet, so I'm trying to locate where that would be.

Another weird thing I noticed is that, we have cellular as backup.  When the primary internet goes offline, the cellular takes over slowly (about 5 minutes), by that time, the primary comes up.  Just like if we were unplugging the primary cable from the Comcast modem and plugging back in.  I guess when the cellular takes over, it gives the Comcast modem enough time to reset?

[Nick]

So you have an MX in play for the gateway, do you have any MS switches?

You need to isolate and check each switch one by one to confirm what is going on. Keep in mind that the dashboard can show the mismatch for a while before it clears

[tantony]

MX for the gateway.  No MX switches, but mix of Netgear / Ubiquity and couple TrendNet switches.

I figured the dashboard is not real time, so I'll have to trace each up link cables manually.

[Nick]

Unfortunately yes - it can take a while I've noticed for the mismatch errors to clear. In an extreme case we waited 2 hours before it cleared.

Localise and trace the issues down switch by switch, it shouldn't take too long. Then get on with the case for Meraki Switches, you'd have your feet up already if you had them in place!

[BrechtSchamp]

Yeah I think it will probably timeout. The error comes up when the switch receives a packet with a source IP in an unexpected subnet. But the switch will not actively reach out to that IP to see if it's still there (it can't because it doesn't have an IP in that range).

[tantony]

Can VLAN mismatch cause internet to drop?  

[Nick]

Not unless its causing a routing issue or changing the uplink on the switch

[tantony]

So far, since fixing the one switch internet is staying up for longer than before 

[tantony]

I’m still seeing the VLAN mismatch, but they’re all coming from our AXIS ip cameras. 

Any my idea why the camera is doing this?

[BrechtSchamp]

Maybe the camera's have some kind of default IP address that is there permanently. Does the error give you more details about which exact IP address is being detected?

[tantony]

The cameras have static ip on the correct subnet. It does have ipv6 on the wrong subnet, but ipv6 is disabled, so it shouldn’t be picking it up.

I’ll check the logs for more info. 

[Nick]

The camera's don't do any form of VLAN tagging do they? Long shot but they could be tagging their traffic