Multi-WLAN port router Principle Analysis

Multi-WLAN port router Principle Analysis
At present, there are many vrouters with multiple WAN ports (WAN interfaces) on the market. Many people ask if the multi-WAN port vro is better than a single WAN port vro? In which scenarios do I need a multi-WAN router? What is the purpose of a Multi-Wan port router? How to use it? What are the benefits of using it? Below we take TP-LINK dual WAN port router TL-R480 + and multi WAN port router TL-R488 as an example to answer these questions.
Answer this question first. Is a multi-WAN port router always "faster" than a single WAN router "?

A vro with multiple WAN ports must first be built on the premise that the performance of the vro itself is strong enough, and the processing capability of the vro with respect to the egress bandwidth is sufficient. If the processing capability is limited, the multi-Wan port is purely a decoration. For example, a factory can make 10 thousand products a day, but only one freight truck can deliver only five thousand products a day. In this case, you need to add a freight truck. However, if there are only three thousand pieces of output per day, but two freight trucks are also used, it will not work, increasing costs. TP-LINK multi-Wan port router is built on the basis of the full router processing capabilities, you can choose with confidence, in the choice of Multi-Wan port router, you must be careful to evaluate its performance, one thing is for your reference: If the vro uses the ARM7 kernel or a fairly high-performance processor and the clock speed is less than 100 M, it can be basically determined that its performance is insufficient to support multiple WAN ports.

TP-LINK TL-R480 + dual-WAN router

TP-LINK TL-R488 four WAN port router
Generally, multiple WAN ports have three purposes: Increasing outbound bandwidth, backing up lines, and providing more content services.
Increasing the egress bandwidth is the easiest way to understand. In most regions, only 1-2 M bandwidth is enabled, and Ethernet bandwidth is only 10 M bandwidth. No matter how fast the LAN is, how powerful the router processing capability is, and how much outbound bandwidth is, everyone is here, and heroes are useless. Using multiple WAN ports, such as dual-WAN port TL-R480 +, using two ADSL or Ethernet broadband lines, since the two WAN ports can be load balancing (the following will be explained in detail ), so it is equivalent to extending the total egress bandwidth to twice the original, the same with the four WAN port of the TL-R488 can be extended to four times the total egress bandwidth. At present, both ADSL and 10 M Ethernet bandwidth have very low monthly subscription fees, and the costs of applying for more than a few items are limited. The bandwidth has increased exponentially with limited fees, for larger networks, it is very good. Of course, you can also rent M access from the carrier, but the monthly cost of tens of thousands of packages is too expensive. In contrast, the multi-Wan port solution can achieve the same effect at a very small cost. Why not? From the perspective of total egress bandwidth, it is 1 + 1 = 2. The reason why we say that using multiple WAN ports is 1 + 1> 2 is that in addition to increasing the egress bandwidth, there are other benefits to using multiple WAN ports.
The second purpose is line backup. Network faults make everyone unable to access the network, which is the most annoying thing. One of the common network faults is access line faults, which may be ISP terminal equipment faults, cable faults, or client Modem faults, which are not hard to see. If you use a multi-Wan port router, apply for multiple lines and use multiple Modem lines, these lines can also be of different carriers, such as China Telecom's ADSL and 10 M Ethernet of China Netcom, when an ISP, cable, or Modem fails, the data traffic will be re-allocated to a non-Faulty port, and the entire network will not be interrupted. In the past, several single-WAN-Port Routers were used to distribute the big data traffic in the network at the same time. However, this solution requires people to divide the network into several groups, one vro and the other, it is equivalent to several local networks. On the one hand, it is very troublesome to configure gateway settings for all computers to correspond to different routers one by one. On the other hand, inter-group communication needs to be switched back from outside the network, it is not only slow but also takes up valuable resources for outgoing bandwidth that is already insufficient, and once a line or Modem fails, all computers in the group that belong to this line will be unable to access the network.
The third purpose is to provide more content services. Different ISPs provide different game, chat, video-on-demand, and other services. These different content services are placed on the servers of different ISPs. to enjoy these services, you must apply for access from the corresponding ISP. To provide multi-ISP content services, you must apply for multi-ISP access and use a multi-Wan port router.
The multi-Wan port router has so many functions and benefits, how can it be used to achieve results? The following describes how the multi-Wan Port Works.
Multiple WAN ports involve interworking between ports. The term "WAN Port Scheduling" is called "WAN Port Scheduling Policy ". The most important scheduling policies are Server Load balancer and backup policies.
As mentioned above, the increase of outbound bandwidth is achieved through Server Load balancer. The role of Server Load balancer is to rationally distribute network data traffic by port. For example, TL-R480 + has two WAN ports, we applied for two 10 M Ethernet broadband lines, assuming the network data traffic is exactly 20 M, a reasonable load balancing policy should be a port distribution of 50%, in this way, each port is exactly 10 M, and the total outbound traffic is 20 M. If load balancing is not doing well, one port is divided into 60%, and the other port is 40%, then 60% of the ports are allocated to 12 M, exceeding 10 M bandwidth and being overloaded. 40% of ports are allocated to only 8 M, bandwidth is rich, and the total outbound traffic is only 10 M + 8 M = 18 M. This is just the simplest example, the actual situation will be much more complicated, such as the TL-R488 has four WAN ports, may apply for four incoming lines, and the bandwidth of each incoming line may be different, the uplink and downstream bandwidths of the same inbound line may be different, and one or more failures may occur on the four lines. In these cases, more complex scheduling policies are required. The simplest strategy is to separate upstream and downstream bandwidths regardless of the bandwidth of each incoming line. If there is a line failure, the bandwidth is evenly divided by the number of ports, for example, the four WAN ports are 25% for each port, which may cause overload of ports with small bandwidth, waste of ports with large bandwidth, and constantly send invalid data to faulty lines, far less than 1 + 1 = 2,
At present, some vrouters with multiple WAN ports on the market adopt this unscientific strategy. Some products are slightly better, allowing you to specify the proportion allocated to each port by yourself, but this method requires you to understand your own policies and then manually configure them, and it cannot solve the problem of line faults, unless you know that the router is interrupted after a fault occurs, you have to reschedule the new allocation scheme, and you have to interrupt the router after the fault is restored. This is complicated and troublesome, the network may be interrupted from time to time. The load balancing policy of TP-LINK multi-Wan port router is a dynamic automatic traffic allocation policy based on the bandwidth ratio, there is no configuration option for the Server Load balancer policy on the user interface, and everything is automatically completed by the router, and when the WAN port changes (such as line failure and recovery) it will be automatically adjusted to the most reasonable status, without interrupting the work of the router or manual adjustment. The following is a simple example to help you understand the policy process.
TL-R488, WAN1 Port 2 m adsl line, WAN2, 3, 4 are 10 M Ethernet bandwidth. When configuring the WAN port, you must enter the upstream and downstream bandwidth of the line. You only need to enter the upstream and downstream bandwidth according to the parameters specified by the ISP, for the sake of simplicity, we also assume that the uplink and downlink bandwidths are the same, and the line starts to work normally. Now that the router knows how many lines are connected and how much bandwidth each line is, it automatically allocates data traffic to four ports, including WAN1 2/32, WAN2, 3, 4, and 10/32 respectively. This is based on the bandwidth ratio allocation, and all ports can be used to the maximum extent. Assuming that the WAN2 line is faulty and the vro detects the fault, the WAN2 is automatically blocked and the data traffic is re-allocated, with WAN1 2/22, WAN3, and 4 10/22, respectively, in addition, the WAN2 line fault is notified to the Network Manager via the preset email address via email for repair. After WAN2 is shielded, The vro will always detect its status. Once the connection is restored, the allocation ratio will be adjusted back to WAN1 2/32, WAN2, and 10/32, respectively. It should be noted that all these tasks are completed automatically by the vro without manual intervention, and the vro remains working, and the user in the network does not feel all the changes in the network. This is just a simple example. In fact, the internal policy process is more complicated. It is not impossible for professionals to have a deep understanding of it, and simple configuration interface options cannot accommodate all possible conditions and policies. These work should be done by the manufacturer rather than pushed to the user. What users get is an intelligent product that can work automatically in the most reasonable way, this is TP-LINK multi-Wan port router and other manufacturers of Multi-Wan port router compared to the characteristics and advantages.
Similarly, the TP-LINK multi-Wan port router is also fully automated in the backup policy. A general multi-Wan port router has a backup policy option (or backup mode) on the configuration interface. You need to specify which is the main line and which is the backup line, the backup line is enabled only when the main line is faulty. The problem with this method is: Since multiple Wan Port Routers are used, an important purpose is to increase the egress bandwidth. In the backup mode, only one port can work, and the egress bandwidth cannot be increased. In addition, it may take several seconds to several minutes from detecting a line fault to enabling a backup line, which may cause network interruption. Vrouters in this way often do not support automatic detection of fault relief and recovery of line configuration. manual adjustment is required. TP-LINK multi-Wan port router uses automatic adaptive backup policy, and combined with the load balancing policy (for details, see the example in the above section of the load balancing policy), to achieve seamless backup, this is TP-LINK multi-Wan port router and other manufacturers of Multi-Wan port router compared to the characteristics and advantages.
In addition to these intelligent load balancing and backup policies, the TP-LINK multi-Wan port router also allows users to make some special policies. There are three main aspects.
First, each WAN port can be enabled or disabled separately (all ports are enabled by default). This mainly takes into account the following two situations, did not use all WAN ports (for example, buy a TL-R488 but only need to apply for three inbound), or although each WAN port is configured with inbound, but some lines are not monthly billing, the bandwidth of other lines is enough at ordinary times. In order to save the cost, it is usually switched off and enabled only when necessary.
Second, you can specify a priority channel based on the source IP address, that is, some computers in the specified network must exit from the specified WAN port, unless this line is faulty, other WAN ports will be used. This mainly takes into account two requirements: one is the special requirements of network management, and the other is the distinction between for-profit network charging levels, such as Internet cafes, game zones and common zones, when the game zone has high requirements on network bandwidth and speed, it is allocated to high-speed lines. Charges are relatively high, and normal areas are allocated to low-speed lines, with relatively low fees. Of course, the Internet cafe owner does not want to designate the computer on the line to fail to access the network when the line is faulty, or want him to continue consumption. Therefore, the policy is to specify a priority channel and prioritize the access from here, when there is a problem, you can also exit from other ports.
Third, the channel can be specified by the target IP address, that is, the specified server (such as a certain game server) must go out of the specified WAN port. This is easy to understand, because you have to go to China Telecom's game servers to go through China Telecom's line, or you will not be able to get there. This is the ISP's method to promote its business. As mentioned above, one of the purposes of multiple WAN ports is to provide more content services. This policy is specifically designed for this purpose. With this policy, you can apply for lines of different ISPs to obtain special content services of different ISPs.
A policy that specifies a channel by source or destination IP address is also a feature of a TP-LINK multi-Wan port router.
The above describes the use of multi-Wan port router and its working principle and use method, also analyzes the characteristics and advantages of the Multi-Wan port router of TP-LINK. From the above analysis, we can see that for networks with high egress bandwidth, uninterrupted operation, and high content service requirements, multiple Wan Port Routers are required, such as Internet cafes and enterprise networks. A well-performed multi-Wan port router can achieve 1 + 1> 2.