topic Palo HA in Azure - traffic flow in VM-Series in the Public Cloud

Palo HA in Azure - traffic flow

JimMcGrady — Tue, 17 May 2022 05:58:31 GMT

I have a pair of VM300 gateways running 9.1.13 in Azure. I'm using a 'load balancer sandwich' approach to provide active active HA.

The public load balancer in front of the firewalls does a good job of delivering inbound traffic. However, routing to the internal destinations from the inside of the firewalls isnt ideal currently. I find i have to source nat the traffic to each firewall's internal interface if i want the replies to take the correct return path. This loses the original internet client's real IP. Without this source natting, even if the return traffic routes correctly to the firewall pair, it may not egress out the same gateway that it entered through. Making the traffic lose state.

Is there another way i can use two firewalls in active active HA and have the return traffic flow correctly?

Re: Palo HA in Azure - traffic flow

sthornton — Mon, 23 May 2022 17:16:22 GMT

Hi Jim. You should not need to be using source NAT to maintain session symmetry in Azure. Which load balancer are you using on the inside? Basic, Standard SKU?

Re: Palo HA in Azure - traffic flow

JimMcGrady — Tue, 24 May 2022 01:38:58 GMT

Hi Scott. Traffic initiated from internet passes through the outside load balancer (standard public SKU) to the Palo pair, and then straight to the backend servers. I am using port Natting between the outside LB and the Palo pair to allow traffic differentiation. Without a source NAT, the reply traffic uses the user defined route which sets the inside load balancer (standard sku internal) as its next hop. a traffic capture sees this delivered to either Palo, not necessarily to the one the original traffic came through.