Machine traceroute not going out preferred WAN interface that I set on

[GelC]

Hi Team,

Just wondering why when I do a traceroute on my machine it dont go out on preferred wan interface I set on Internet Traffic under Flow preferences. It still go out on the primary link but when i check my public ip and do a speedtest it shows my secondary link. By the way my load balancing is disable. 

[MarcP]

Can you tell/show us your settings under flow preferences - internet traffic?

[GelC]

Hi Marc, see image for the reference.

Its just weird that every time i do traceroute on my machine the traceroute still show my primary link not the wan2 even if i already set it up on the internet traffic. is there something im missing out on my configuration?

Based on the documentation "Flow preferences for internet-bound traffic can be configured to force traffic over a specific uplink based on its source and/or destination" 

[KarstenI]

Are you using Windows? Tracert is based on ICMP on that platform and ICMP is nor handled by the flow preferences. Can you try it from a linux box ans see if the route changes?

[GelC]

Hi Karsten

Yup using windows machine. I see so the internet traffic go out to wan2 then? even if the traceroute result does not show that its coming out to wan2? is this a bug? 

Tried your suggestion to use ubuntu machine same the mtr shows primary link instead of the wan2 i set on the internet traffic. 

[KarstenI]

I would not say that it's a bug, just that it is an unexpected "feature" of the Meraki implementation. At least it is a documented feature.

And MTR is again the wrong test as it also uses ICMP and the MX will ignore the flow preference for it. I think that all these tools that show the public IP are the right thing to test it. Or to do a packet-capture on the secondary WAN and see if the UDP/TCP traffic leaves this interface.

[GelC]

Noted on this Karsten, 

Correct me if im wrong on my understanding

So basically the icmp will always go out to the primary link correct? But the machine internet traffic which is set routed to will go out to wan2 right?

So if i want to check the latency on a certain destination using traceroute or mtr i'll just use the built in traceroute and mtr on meraki and disregard the traceroute and mtr on the terminal/cmd

[KarstenI · Accepted solution]

Correct!

Just the "normal" traceroute on linux should show the correct result as it is based on UDP and only optionally on ICMP.

[GelC]

Great! Thank you Karsten! Cheers