Routed mode OSPF causes MX to loose connectivity

[Shaun1387]

Hi All,

I have a strange issue with an MX i have in my SD-WAN lab here. 

I have this MX configured in Routed/Spoke mode using a single IP on the LAN side. Looking at the documentation, in this mode it should support OSPF connectivity to a peer on its LAN ports.

I have a Cisco 2951 connected to the LAN port correctly configured for OSPF. When I switch on OSPF in the dashboard two things happen.

1. The LAN port on the MX looses connectivity. i ran up a span on the port and could see on wireshark that the MX is not responding to any traffic (unicast/multicast) being sent to it and it occasionally sends ICMP's to the 2951 along with a load of other broadcasts (LLDP for example). Its ignoring the OSPF hellos as well as ICMP's from the 2951 and other hosts, in fact everything. It does seem to have an ARP entry for the 2951 as does the 2951 for the MX but thats about all thats happening.
2. The MX drops off the dashboard completely. No idea why this should be happening.

If i then turn OSPF off on the dashboard, reset the MX and let it boot, it pulls down the updated config and works fine again.

My understanding is that this config should work but i cant understand why the LAN Port would just start ignoring traffic. Not sure whats happening on the WAN side, I havent looked at that yet but i suspect its something similar.

Has anyone seen this before or know why it may be happening ? have i misunderstood something fundamental here. ?

Cheers for any help guys !

Shaun

[ww]

Sounds like a bug on a specific firmware version. You could try another fw or create a support case

[PhilipDAth]

Is the MX running current stable firmware (or better)?

Is the MX plugged into an access mode switch port (or a trunk port with the correct native VLAN)?

[Shaun1387]

Thanks for the reply's guys,👍

Hi Philip,

the MX is running MX16.16 according to the dashboard. 

Currently, i have it connected to the router via a dedicated vlan (no SVI) and a pair of access ports on a 3750 switch, just so i could do a port mirror on the traffic. I have tried it cabled directly to a layer 3 port on the router with the same results.

it works fine with OSPF disabled, drops off the network when OSPF is enabled.

I will see if i can find any release notes for 16.16 , see if there is any mention of this as a caveat.

Im having a few other oddities happening with this particular setup, I have a vMX in azure running as a Hub and two MX devices running 16.16. The vMX site to to site vPN is showing all green, the two spokes are showing disconnected from VPN registry, a packet sniff shows there are clearly talking to each other though... one for another time perhaps, but im now wondering if its got to do with the software on the MX as you suggest. hmmmm

[Shaun1387]

quick update.. have upgraded the MX to 16.16.4. Made no difference

[Shaun1387 · Accepted solution]

further update. 

Opened a support call with Meraki, turns out the code on the MX was actually version 10 despite the dashboard reporting 16.16.x 

Meraki support did a step update first to 12.x , then 15.x then 16.16.4.

OSPF now working fine and my VPN oddities have cleared up.

bizarre !!!! 😲

[CptnCrnch]

Wow, that's an interesting one! Thanks for keeping us posted. 👍

[PhilipDAth]

Double Wow!  I wonder how it even managed to get such an archaic version of code.

[Shaun1387]

Cheers guys, beats me ! It was the last thing I had thought would be the issue but now that we know its a possibility hopefully it will help others when strange things start happening.

😁