Our previous article explained how Palo Alto Firewalls make use of Security Zones to process and enforce security policies. This article will explain the different configuration options for physical Ethernet and logical interfaces available on the Palo Alto Firewall.

It’s easy to mix and match the interface types and deployment options in real world deployments and this seems to be the strongest selling point of Palo Alto Networks Next-Generation Firewalls. Network segmentation becomes easier due to the flexibility offered by a single pair of Palo Alto appliances.

Below is a list of the configuration options available for Ethernet (physical) interfaces:

• Tap Mode
• Virtual Wire
• Layer 2
• Layer 3
• Aggregate Interfaces
• HA

Following are the Logical interface options available:

• VLAN
• Loopback
• Tunnel
• Decrypt Mirror

The various interface types offered by Palo Alto Networks Next-Generation Firewalls provide flexible deployment options.

Tap Mode Deployment Option

TAP Mode deployment allows passive monitoring of the traffic flow across a network by using the SPAN feature (also known as mirroring).

A typical deployment would involve the configuration of SPAN on Cisco Catalyst switches where the destination SPAN port is the switch port to which our Palo Alto Firewall connects, as shown in the diagram below:

 

Figure 1. Palo Alto Next Generation Firewall deployed in TAP mode

The advantage of this deployment model is that it allows organizations to closely monitor traffic to their servers or network without requiring any changes to the network infrastructure.

During the configuration of SPAN it is important to ensure the correct SPAN source and SPAN Destination ports are configured while also enabling Tap mode at the Firewall.

What makes Palo Alto Networks Next-Generation Firewall (NGFW) so different from its competitors is its Platform, Process and Architecture. Palo Alto Networks delivers all the next generation firewall features using the single platform, parallel processing and single management systems, unlike other vendors who use different modules or multiple management systems to offer NGFW features.

More technical and how-to articles covering Palo Alto's Firewalls can be found in our Palo Alto Networks Firewall Section

Palo Alto Networks Next-Generation Firewall’s main strength is its Single Pass Parallel Processing (SP3) Architecture, which comprises two key components:

1. Single Pass Software
2. Parallel Processing Hardware

Figure 1.   Palo Alto Networks Firewall Single Pass Parallel Processing Architecture

Single Pass Software

Palo Alto Networks Next-Generation Firewall is empowered with Single Pass Software, which processes the packet to perform functions like networking, user identification (User-ID), policy lookup, traffic classification with application identification (App-ID), decoding, signature matching for identifying threats and contents, which are all performed once per packet as shown in the illustration below:

Figure 2: Palo Alto Networks Firewall - Single-Pass Architecture Traffic Flow

This processing of a packet in one go or single pass by Palo Alto Networks Next-Generation Firewall enormously reduces the processing overhead, other vendor firewalls using a different type of architecture produce a significantly higher overhead when processing packets traversing the firewall. It’s been observed that the Unified Threat Management (UTM), which processes the traffic using multi-pass architecture, results in process overhead, latency introduction and throughput degradation.

The diagram below illustrates the multi-pass architecture process used by other vendors’ firewalls, clearly showing differences to the Palo Alto Networks Firewall architecture and how the processing overhead is produced: