FortiGate
FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
hlngan
Staff
Staff
Article Id 256836
Description This article describes how VPN HA routing works against SD-WAN.
Scope FortiGate.
Solution

Backgrounds:

 

The user has two VPN tunnel setups with auto-negotiate enabled:

 

edit 1
    set dst 10.1.0.0 255.255.0.0
    set device "VPN-A"
    set comment "Main Subnet"
next

    edit 8
        set dst 10.2.0.0 255.255.0.0
        set device "VPN-B"
        set comment "Main Subnet"
    next

 

When a VPN tunnel is established with a static route and at the same time exists within the SD-WAN member.

 

1) When there is no health-check for IPsec tunnel(SDWAN member) with 'update-static-route enable' required:

- When VPN-A is down.

- System will detect VPN-A is down.

- Static route on VPN-A will be removed from the routing table.

- Traffic will flow to VPN-B using the static route on VPN-B.

- So that in this scenario the failover of the traffic is triggered by a static route updated on the VPN interface, not from SD-WAN even if the member is included in the SD-WAN.

 

2) When there is a health-check for IPsec tunnel (SD-WAN member) with 'update-static-route enable' required.

 

config system sdwan
...
    config health-check
        edit <name>
            set server x.x.x.x
        next
      end
    end

 

- When VPN-A is down.

- SDWAN health check will notice the VPN-A is down.

- Traffic will be routed to VPN-B.

- In this case the failover is triggered by SD-WAN

 

3) If the customer does not want to be involved in SD-WAN:

- Customer can set up a link-monitor to trigger the failover:

 

config system link-monitor
  edit <name>
    set srcintf <IPsec phase1-interface name>
    set server x.x.x.x
    set source-ip y.y.y.y
<-----IPsec tunnel IP or an internal interface IP address.
  next
end

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