Introduce LAN extension mode for FortiExtender

LAN extension is a configuration mode on the FortiGate that allows the FortiExtender to provide remote thin edge connectivity back to the FortiGate over a backhaul connection. The FortiExtender deployed at a remote location will discover the FortiGate access controller (AC) and form an IPsec tunnel (or multiple tunnels when multiple links exist on the FortiExtender) back to the FortiGate. A VXLAN is established over the IPsec tunnels to create an L2 network between the FortiGate and the network behind the remote FortiExtender.

In the following example, the FortiGate 501E is the FortiExtender AC that provides secure internet access to the remote network behind the FortiExtender 200F thin edge. The FortiGate 501E has two WAN connections: one is used as an inbound backhaul connection and the other for outbound internet access. The FortiExtender 200F has two wired WAN/uplink ports connected to the internet. Once the FortiExtender discovers the FortiGate AC and is authorized by the FortiGate, the FortiGate pushes an extender profile to the FortiExtender. From the profile, the extender uses the configurations to form two IPsec tunnels back to the FortiGate. Additional VXLAN aggregate interfaces are automatically configured to create an L2 network between the FortiExtender LAN port and a virtual LAN extension interface on the FortiGate. Clients behind the FortiExtender can now connect to the internet through the FortiGate that secures the internet connection.

Authorizing the devices

To discover and authorize the FortiExtender in the GUI:

1. On the FortiGate, enable the Security Fabric connection on port3 to allow the FortiExtender to connect over CAPWAP:
   1. Go to Network > Interfaces and edit port3.
   2. In the Administrative Access section, select PING and Security Fabric Connection.
   3. Click OK.
2. On the FortiExtender, connect to the CLI via SSH and set the AC server address to the FortiGate:

   config system management
       set discovery-type fortigate
       config fortigate
           set ac-discovery-type static
           config static-ac-addr
               edit 1
                   set server 1.1.1.10
               next
           end
           set ac-ctl-port 5246
           set ac-data-port 25246
           set discovery-intf port1 port2
           set ingress-intf 
       end 
   end

   Once the FortiExtender’s discovery packet reaches port3 on the FortiGate, the FortiExtender will appear under Network > FortiExtenders as unauthorized.

   

   The FortiGate automatically creates a VPN profile for this FortiExtender, which appears on the VPN > IPsec Tunnels page.

   

   The FortiGate also creates an extender profile for that model of FortiExtender, which appears on the Network > FortiExtenders > Profiles tab.

   

   The FortiExtender profile is configured based on the FortiExtender model. It automatically selects Load Balance (as the Link load balance setting), the IPsec interface, and the pre-configured tunnel.

   

3. Authorize the FortiExtender:
   1. Go to Network > FortiExtenders, select the Managed FortiExtenders tab, and edit the discovered FortiExtender.
   2. In the Status section, enable Authorized.

      

   3. Click OK. The device now displays as authorized.

      

To discover and authorize the FortiExtender in the CLI:

1. On the FortiGate, enable the Security Fabric connection on port3 to allow the FortiExtender to connect over CAPWAP:

   config system interface
       edit "port3"
           set vdom "root"
           set ip 1.1.1.10 255.255.255.0
           set allowaccess ping fabric
        next
    end

2. On the FortiExtender, connect to the CLI via SSH and set the AC server address to the FortiGate:

   config system management
       set discovery-type fortigate
       config fortigate
           set ac-discovery-type static
           config static-ac-addr
               edit 1
                   set server 1.1.1.10
               next
           end
           set ac-ctl-port 5246
           set ac-data-port 25246
           set discovery-intf port1 port2
           set ingress-intf 
       end 
   end

3. The FortiGate discovers the FortiExtender and some basic configurations are automatically initialized in FortiOS:

   config extension-controller extender
       edit "FX0035919000000"
           set id "FX200F5919000000"
           set device-id 0
           set extension-type lan-extension
           set profile "FX200F-lanext-default"
       next
   end

4. An IPsec tunnel is automatically created for the detected FortiExtender:

   config vpn ipsec phase1-interface
       edit "fext-ipsec-ksKS"
           set type dynamic
           set interface "port3"
           set ike-version 2
           set peertype one
           set net-device disable
           set proposal aes128-sha256 aes256-sha256 aes128-sha1 aes256-sha1
           set localid "localid-5bzuqs54dGni2TT0x2NePg0HexHW2piQ44aZ4NiGe8SVxxBnFuiqZqo"
           set dpd on-idle
           set comments "[FX200F-lanext-default] Do NOT edit. Automatically generated by extender controller."
           set peerid "peerid-svxVy5bZbPxZdfoIQBNA7YrkSKBA9Ui1vZsvYcVrgp1Uy0aFMCVZzGzh"
           set psksecret ENC <secret>
           set dpd-retryinterval 60
       next
   end
   config vpn ipsec phase2-interface
       edit "fext-ipsec-ksKS"
           set phase1name "fext-ipsec-ksKS"
           set proposal aes128-sha1 aes256-sha1 aes128-sha256 aes256-sha256 aes128gcm aes256gcm chacha20poly1305
           set comments "[FX200F-lanext-default] Do NOT edit. Automatically generated by extender controller."
       next
   end

5. A FortiExtender profile is created for the model of the detected FortiExtender:

   config extension-controller extender-profile
       edit "FX200F-lanext-default"
           set id 0
           set model FX200F
           set extension lan-extension
           config lan-extension
               set link-loadbalance loadbalance
               set ipsec-tunnel "fext-ipsec-ksKS"
               set backhaul-interface "port3"
               config backhaul
                   edit "1"
                       set port port1
                   next
                   edit "2"
                       set port port2
                   next
               end
           end
       

6. Authorize the FortiExtender:

   config extension-controller extender
       edit "FX0035919000000"
           set authorized enable
       next
   end 

Backhaul tunnel and VXLAN auto-deployment

Once the FortiExtender is authorized, the FortiGate immediately pushes the IPsec tunnel configuration to the extender. This forces the FortiExtender to establish the tunnel and form the VXLAN mechanism.

In the following diagram, the VXLANs are built on the IPsec tunnels between the FortiExtender and the FortiGate. The two VXLAN interfaces are aggregated to provide load balancing and redundancy. A softswitch is also used to combine the aggregate interface with the local LAN ports, which allows the LAN ports to be part of the VXLAN. This ultimately combines the local LAN ports with the virtual LAN extension interface on the FortiGate AC.

Underlying configurations that are automatically configured:

1. The FortiExtender receives the IPsec configurations from the FortiGate and creates the corresponding tunnels for each uplink:

   config vpn ipsec phase1-interface
       edit le-uplink-port1
           set ike-version 2
           set keylife 86400
           set proposal aes128-sha256 aes256-sha256 3des-sha256 aes128-sha1 aes256-sha1 3des-sha1
           set dhgrp 14 5
           set interface port1
           set type static
           set remote-gw 1.1.1.10
           set authmethod psk
           set psksecret ******
           set localid peerid-svxVy5bZbPxZdfoIQBNA7YrkSKBA9Ui1vZsvYcVrgp1Uy0aFMCVZzGzh
           set peerid localid-5bzuqs54dGni2TT0x2NePg0HexHW2piQ44aZ4NiGe8SVxxBnFuiqZqo
           set add-gw-route enable
           set dev-id-notification disable
       next
       edit le-uplink-port2
           set ike-version 2
           set keylife 86400
           set proposal aes128-sha256 aes256-sha256 3des-sha256 aes128-sha1 aes256-sha1 3des-sha1
           set dhgrp 14 5
           set interface port2
           set type static
           set remote-gw 1.1.1.10
           set authmethod psk
           set psksecret ******
           set localid peerid-svxVy5bZbPxZdfoIQBNA7YrkSKBA9Ui1vZsvYcVrgp1Uy0aFMCVZzGzh
           set peerid localid-5bzuqs54dGni2TT0x2NePg0HexHW2piQ44aZ4NiGe8SVxxBnFuiqZqo
           set add-gw-route enable
           set dev-id-notification disable
       next
   end

2. VXLAN interfaces are formed over each tunnel:

   config system vxlan
       edit le-vxlan-port1
           set vni 0
           set remote-ip 10.252.0.1
           set local-ip 10.252.0.2
           set dstport 9999
       next
       edit le-vxlan-port2
           set vni 0
           set remote-ip 10.252.0.1
           set local-ip 10.252.0.3
           set dstport 9999
       next
   end

3. An aggregate interface is configured to load balance between the two VXLAN interfaces:

   config system aggregate-interface
       edit le-agg-link
           set mode loadbalance
           set mapping-timeout 60
           config members
               edit le-vxlan-port1
                   set interface le-vxlan-port1
                   set weight 1
                   set health-check-event le-agg-port1
                   set health-check-fail-cnt 5
                   set health-check-recovery-cnt 5
               next
               edit le-vxlan-port2
                   set interface le-vxlan-port2
                   set weight 1
                   set health-check-event le-agg-port2
                   set health-check-fail-cnt 5
                   set health-check-recovery-cnt 5
               next
           end
       next
   end

4. The softswitch bridges the aggregate interface and the local LAN to connect the LAN to the VXLAN bridged L2 network, which spans across to the FortiGate LAN extension interface:

   config system switch-interface
       edit le-switch
           set members le-agg-link lan
           set stp disable
       next
   end

Configuring the LAN extension and firewall policy

Once the IPsec tunnel is set up and the VXLAN is created over the IPsec tunnel, the new LAN extension interface appears on the FortiGate.

To configure the LAN extension interface and firewall policy:

1. Edit the LAN extension interface:
   1. Go to Network > Interfaces and edit the LAN extension interface.

   2. Configure the IP/Netmask (9.9.9.99/255.255.255.0). Other devices on the remote LAN network will configure this as their gateway.

   3. Optionally, enable DHCP Server to assign IPs to the remote devices using DHCP.

   4. Click OK.

2. Configure the firewall policy to allow traffic from the LAN extension interface to the WAN (port1):
   1. Go to Policy & Objects > Firewall Policy and click Create New.
   2. Enter the following:

      Incoming Interface	FX0035919000000
      Outgoing Interface	port1
      Source	all
      Destination	all
      Schedule	always
      Service	ALL
      Action	ACCEPT
      NAT	Enable (NAT)

   3. Configure the other settings as needed, such as security profiles.
   4. Click OK.

      This policy allows the remote LAN clients to access the internet through the backhaul channel. Clients in the remote LAN behind the FortiExtender will now be able to receive an IP over DHCP and reach the internet securely through the FortiGate.