ISP failover with Path Monitoring help? Incomplete Aged-out traffic issue. PA 3020

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ISP failover with Path Monitoring help? Incomplete Aged-out traffic issue. PA 3020

L2 Linker

I am using a PA 3020.   


We have an ISP1 which is our main corp internet. 

We have an ISP2 which is also our active Guest network. 


I'm trying to configure ISP1 virtual router with Path Monitoring so that if fails pinging a group of IP's it fails over to ISP2 virtual router. 


Well I have configured Path Monitoring and can trigger it accordingly by monitoring a dead IP. 

However I cannot get to the internet after this kicks in. 

From monitor tab I check my test laptop and the From Zone is till the same, and To Zone has changed. But everything says "aged-out" in the "Session End Reason" column.


Any ideas if there is another issue I need to check? 


L7 Applicator

Why do you have 2 virtual routers?

Easier to have 1 virtual router.

Your could use PBF to route Guest network out from ISP2 link.


Check SNAT IP on outgoing traffic.

Does outgoing traffic match correct NAT rule and it is sourcing from ISP2 public IP?

Enterprise Architect, Security @ Cloud Carib Ltd



The 2 Virtual Routers existed before I inherited the management of the PA (inherited by network admin leaving, which hopefully explains my newbiness).

I am not sure I can swap out everything with 1 single Virtual Router and a PBF right now.

I was hoping to just get Path Monitoring setup with current setup to get ISP redundancy soon, and then have some cushion later to play around with 1 VR and PBF.


When I tested the ISP failover with how it is setup now, enabling Path Monitorign to ping a phantom IP (, it just disconencted my laptop and I couldn't ping or get to websites.

When I checked the traffic log, I could see my requests going to new destiation zone and interface of ISP2, and ISP2's NAT IP.

But on my laptop I just got errors in my browser when trying websites, and no reply when pinging in cmd prompt.


The "General" application log says "incomplete" though for that traffic.

PA support advised maybe it is another switch, that the PA is handing traffic back into our network but my laptop is not getting it? I am not sure what to check to troubleshoot this. we do have 2 HP switches in the MDF

If VR1 routes traffic to VR2 and VR2 to internet.

Does VR2 have route back towards VR1 for return traffic?

Enterprise Architect, Security @ Cloud Carib Ltd



Well I'm not sure. Would this be established via a Static Route within the VR? 

As far as VR2 route back to VR1, this could be setup so only when it is failed over? Because on a normal day to day basis, VR2 with ISP2 is used all day as a guest network and functions fine. 

It's just trying to leverage it as a failover for our ISP1 and corp zone when ISP1 goes down. 


Let's assume that internal network is and guest network is

In this case you need to have static route in VR2 to send traffic towards towards VR1.

It will not affect traffic from VR2 to internet because this has default route and it would not allow guest traffic to internal becvause Security Policy will take care of that part.

Enterprise Architect, Security @ Cloud Carib Ltd


Ahhh ok that makes sense. I will try that. So that would still be require if I did Policy Based forwarding too?
But if i consolidated to one VR it would make it easier ?

With 2VRs you still need routes between them.


PBF is checked before VR.

So if there is route in PBF then this will take precedence.

If no matching PBF then Palo falls back to routes in VR.


This allows you to have 1 VR and PBF that has logic "if traffic comes from Guest zone then send it towards ISP2 and monitor ISP2. If ISP2 is not available then fall back VR"

Enterprise Architect, Security @ Cloud Carib Ltd


Well I will definitely first try the route setup next. I'm excited that it makes sense and am motivated to try this at the next earliest, possible maintenance window overnight versus weekend. 

Let me give this a go, and report back. Hopefully you won't mind visiting back to see how it goes. 

Thanks very much 

Definitely let know how it went.

Enterprise Architect, Security @ Cloud Carib Ltd
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