Correct IP setting when two firewalls connected to one ISP.

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Correct IP setting when two firewalls connected to one ISP.

L4 Transporter

We have two PA's connecting to one ISP. One is just being set up.


The ISP is ""

Route is ""


Is it correct to have both firewall external vlan interfaces as such


FW1 ""

FW2 ""

 Vlan 140






And for the NAT





FW1 Main Nat ""

FW2 Main Nat ""





I ask, because the new firewall is logging packets for the old firewall. I am seeing "x.x.x.99" on the firewall with VIP "x.x.x.122"







It's easy to get confused by Palo Alto's various uses of VLAN.


A "VLAN" interface is different from a "Layer 3" interface that has 802.1q vlan tags enabled.


On a PA device "VLAN" interfaces are used to create a virtual switch using ports on the firewall, and allow them to operate as layer 2 interfaces without routing abilities.  Essentially, it create a bridged interface using all the VLAN interfaces.


If you want to enabled tagged (or untagged) 802.1q vlans on interfaces, then configure them as "Layer 3" and create sub-interfaces with the vlan tag set there.


Would be nice if PA updated their UI to remove the ambiguous and confusing "VLAN" interface type.  "Bridge" would be more accurate.

I couldn't agree with you more.  This really confused me the first time I used PAN and the documentation explaining this wasn't great.

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