Why Use Bridge Mode?
Routers have whatтАЩs known as NAT. When connecting a router that has NAT to a modem with built-in NAT capabilities, you might encounter issues without enabling bridge mode. Additionally, bridge mode helps by:
- Increasing your Wi-Fi coverage and allowing devices to communicate smoothly
- Preventing IP address conflicts and connecting issues
Advantages of Using Bridge Mode
Bridge mode is highly beneficial if you want to extend the range of your WiFi. While its use isnтАЩt limited to businesses, it is mainly used by large-scale offices and commercial spaces where a single router isnтАЩt a viable option.
When youтАЩre close to the ISP-provided WiFi router, you will get a good reception. However, as you move farther away, you start to lose signals to a point where the device is no longer connected to the WiFi network. Bridge mode is an effective solution for this problem, as it тАЬbridgesтАЭ the connection to the further-away network and extends the range.
By connecting multiple routers to a single ISP-provided modem/router, devices connected to the routers will not communicate with each other. Bridge mode allows you to connect numerous devices, extend the WiFi, provide faster speeds, and improve reliability.
When Should You Use Bridge Mode?
You should use bridge mode if:
- YouтАЩre connecting a second router to your network
- YouтАЩre creating a mesh Wi-Fi system for your network
- You want to avoid NAT conflicts
Bridge Mode in a Nutshell
You donтАЩt necessarily have to enable bridge mode in all instances. If your home or office WiFi works great with sound WiFi coverage and doesnтАЩt annoy you with sluggish speeds when you move farther, then thereтАЩs no reason to use bridge mode.
Bridge mode is most effective when youтАЩre moving farther away from your router and need extended WiFi coverage. Also, it helps devices connected to the private network communicate with each other without any performance issues.
Routing mode
If you apply to ISP for a routing-mode WAN link, you will obtain an individual IP network (layer 3) which is separated from any other networks of the ISP. In that case, the ATU-R at a customer premises plays the role of a gateway to route packets between your network and the Internet. In the other words, the ATU-R connects your network with the ISP central office in routing mode. The IP addresses, default gateway and netmask that the ISP provides you can tell you whether a WAN link is routing mode or not. If the number of deducting 3 (network IP, gateway IP and broadcast IP) from the IP range that the netmask determines matches the number of usable IP addresses that ISP provides you, it means you are given a separate network, a routing-mode WAN link. For example, the ISP gives you five usable IP addresses 203.69.118.10 тАУ 203.69.118.14, default gateway 203.69.118.9 and netmask 255.255.255.248. The netmask 255.255.255.248 divides eight IP addresses which contains five host addresses, one gateway address, one broadcast address and one address for the network ID. It just matches the number of the usable IP addresses the ISP provides. In that case you are strongly recommended to configure the WAN link on FortiWAN as Routing Mode.
Bridge mode
Opposite to the routing mode, the ATU-R will play the role of a bridge to combine network segments (data link layer, layer 2) of customer premises and the ISP central office, if the WAN link is in bridge-mode. In that case, ISP allocates a block of IP addresses (or a network segment) of an IP network (layer 3) for you rather than a separate IP network. It implies that you and other customers (other network segments) of the ISP that in the same IP network use the same gateway, which is located at the ISPтАЩs central office.
You can identify a bridge-mode WAN link by the IP addresses, default gateway and netmask that the ISP provides you. If the number of deducting 3 (network IP, gateway IP and broadcast IP) from the IP range that the netmask divides is larger than the number of usable IP addresses that ISP provides you, it means you are given a segment of a IP network, a bridge-mode WAN link. For example, the ISP gives you three usable IP addresses 61.88.100.1 тАУ 61.88.100.3, default gateway 61.88.100.254 and netmask 255.255.255.0. The netmask 255.255.255.0 divides 256 IP addresses which contains 253 host addresses, one gateway address, one broadcast address and one address for the network ID. The number of host addresses that the netmask divides (253) is larger than number of IP addresses the ISP provides (3). You have to configure a WAN link to FortiWAN as Bridge Mode: One Static IP if the WAN link is in bridge-mode and ISP allocates only one IP address for you, or
Bridge Mode: Multiple Static IP if the WAN link is in bridge-mode and ISP allocates multiple IP addresses for you.
Traffic going to or coming from the near WAN (see Near WAN) is treated by FortiWAN in two different ways for routing-mode WAN link and bridge-mode WAN link. Configuring WAN links to FortiWAN as mismatched WAN type results in unexpected behaviors to traffic.
See also
l Configurations for a WAN link in Routing Mode l Configurations for a WAN link in Bridge Mode: One Static IP l Configurations for a WAN link in Bridge Mode: Multiple Static IP l Configurations for a WAN link in Brideg Mode: PPPoE l Configurations for a WAN link in Bridge Mode: DHCP
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