Resolving Asymmetric Routing Issue in a Network with PfSense Router

Resolving Asymmetric Routing Issue in a Network with PfSense Router

In this article, we will discuss how to resolve the asymmetric routing issue in a network that has a PfSense router, an untagged network 10.1.0.0/23, and a tagged VLAN 40 network 10.1.40.0/24. We will cover the key concepts related to asymmetric routing, its causes, and how to resolve it using PfSense router.

What is Asymmetric Routing?

Asymmetric routing is a network condition where data packets take different paths when traveling from the source to the destination and when returning from the destination to the source. This condition can cause issues in network performance, security, and troubleshooting. In some cases, asymmetric routing is intentional and can improve network performance. However, in most cases, it is unintentional and can lead to problems.

Causes of Asymmetric Routing

Asymmetric routing can be caused by several factors, including:

• Multiple paths between source and destination
• Different routing policies on different routers
• Load balancing and traffic engineering techniques
• Firewall and security devices that modify routing decisions

Resolving Asymmetric Routing Issue in PfSense Router

To resolve the asymmetric routing issue in a network that has a PfSense router, we need to ensure that all data packets take the same path when traveling from the source to the destination and when returning from the destination to the source. We can achieve this by configuring the PfSense router to use the same routing policy for both inbound and outbound traffic.

Here are the steps to configure PfSense router to resolve the asymmetric routing issue:

1. Log in to the PfSense web interface.
2. Go to the System menu and select Routing.
3. Click on the Gateways tab and make sure that the WAN gateway is set as the default gateway.
4. Go to the Firewall menu and select NAT.
5. Click on the Outbound tab and select Manual Outbound NAT rule generation.
6. Add a new outbound NAT rule for the untagged network 10.1.0.0/23 and the tagged VLAN 40 network 10.1.40.0/24.

Interface: WAN
Protocol: Any
Source: 10.1.0.0/23, 10.1.40.0/24
Destination: Any
Translation: WAN address

7. Go to the Firewall menu and select Rules.
8. Add a new firewall rule for the WAN interface to allow inbound traffic from the Internet to the PfSense router.

Interface: WAN
Protocol: Any
Source: Any
Destination: PfSense WAN address
Gateway: WAN gateway
Schedule: None
Description: Allow inbound traffic from the Internet

9. Add a new firewall rule for the LAN interface to allow outbound traffic from the LAN network to the Internet.

Interface: LAN
Protocol: Any
Source: LAN subnet
Destination: Any
Gateway: WAN gateway
Schedule: None
Description: Allow outbound traffic from the LAN network

10. Add a new firewall rule for the VLAN interface to allow outbound traffic from the VLAN network to the Internet.

Interface: VLAN
Protocol: Any
Source: VLAN subnet
Destination: Any
Gateway: WAN gateway
Schedule: None
Description: Allow outbound traffic from the VLAN network

By following these steps, we can ensure that all data packets take the same path when traveling from the source to the destination and when returning from the destination to the source. This will resolve the asymmetric routing issue in the network.

Asymmetric routing is a network condition where data packets take different paths when traveling from the source to the destination and when returning from the destination to the source. It can cause issues in network performance, security, and troubleshooting. To resolve the asymmetric routing issue in a network that has a PfSense router, we need to ensure that all data packets take the same path when traveling from the source to the destination and when returning from the destination to the source. We can achieve this by configuring the PfSense router to use the same routing policy for both inbound and outbound traffic.

References

• What is Asymmetric Routing
• Outbound NAT
• Firewall Rules