"LAN" Interface Failover configuration - Primary: dedicated Line, Secondary: VPN

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"LAN" Interface Failover configuration - Primary: dedicated Line, Secondary: VPN

L2 Linker

Hi there,


maybe it's not that complicated but I didn't find a post for this scenario:


The LAN of our Clients are in Location1

(~ 200 km)

The LAN of our Servers are in Location2


Location1 and 2 are using the same firewall which is stored in Location 2 because Location 1 has a dedicated line to Location 2.

The Primary connection between Location1 and 2 is via a direct connection through the backbone from our ISP - with private IPv4 Addresses. The Firewall is not involved in the LAN traffic between the locations, just for the internet access.

Everything in this case is fine, but

the secondary connection between Location1 and 2 is via a LTE Router. I've established a Site2Site VPN between the LTE Router and our PaloAlto Firewall incl a tunnel monitor to make sure the connection is always online. In this case the Firewall is involved in the "LAN" and internet traffic.


I do not know how to configure a failover for the case that the primary connection is broken and everything is going through the LTE Site2Site VPN connection.

I´ve tested the basic functionallity of the LTE connection with routes with a lower metric than the primary but that was only to make sure that the LTE is basically working -> has nothing to to with autmatic failover.


My Problem is that the environment is already productive and I only have a 60 minutes maintenance window per week and that's not that easy to find the perfect solution in this short time ( it's a PA-500 😉 could take a looot of time to commit)







Hi there,


i've tried the configuration, but looks like tunnel interfaces or zones can not be used for symmetric return. Any other idea? If you think it's useful I can post the screnshots of my configuration


Error: pbf rule 'LTE-LAN': Source cannot be zone if nexthop list is specified.
Error: pbf rule 'LTE-LAN': Fail to parse symmetric return.
Error: Failed to parse pbf policy
(Module: device)
Commit failed


Error: pbf rule 'LTE-inet': Source interface cannot be tunnel interface when nexthop address list is configured.
Error: pbf rule 'LTE-inet': Fail to parse symmetric return.
Error: Failed to parse pbf policy
(Module: device)
Commit failed

hm, sorry about that, was not aware this doesn't work on tunnel interfaces


The other way you could achieve this is by reversing the routing/pbf part: set up PBF rules for all traffic from and to the regular WAN link with symmetric return, then have a static route as fallback to the LTE VPN tunnel 

Tom Piens
PANgurus - SASE and Strata specialist; (co)managed services, VAR and consultancy

I solved the problem in that way:

I've merged the primary routing configuration into PBF (withouth symmetric return) with zones as source addresses incl interface monitoring. My secondary connections - LTE - is managed via routing.

All my traffic will be sent via the PBF policy and in case that the next hop is not reachable the PBF rule will be disabled and my static routing will send the traffic through the VPN tunnel.


I still have problems with our IP telephones because they are not working when I switch the configuration to PBF like described above. I tested the basic network functionallity with a host in the telephone network and everythings is fine so it must be related to the SIP application etc. ALG is already disabled. The configuration and routing is nearly the same as for the dhcp network.


Any Idea why the network is working but the IP telephones not?

Mission impossible....I do not get it up and running with STUN....and after ~ 8 hours testing I will delay it to maybe end of the year....=/


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