What is backhaul routing and when is it necessary to do backhaul routing?
2022-12-16 13:57:35Network knowledge 2942
Many people don’t understand: What does backhaul routing mean? When do you need to set up the backhaul routing? The editor of IT Memo will share and answer this question with you below. What is backhaul routing? Network transmission is two-way, and when it goes out, it comes back. This concept couldn’t be simpler.
Many people don’t understand: What does backhaul routing mean? When do you need to set up the backhaul routing ? The editor of IT Memo will share and answer this question with you below.
What is backhaul routing?
Network transmission is bidirectional, and when it goes out, it comes back. This concept couldn't be simpler. Return routing is a relative concept. As the name suggests, it refers to the "return route." The backhaul route refers to the router, which sends the user's packets to the external network. After the external network's response packets reach the router, the router needs to send the packets to the user based on the backhaul route. Many people still don't understand why home routers don't need to be used for backhaul routing? Because ordinary home routers do NAT conversion by default, and there is only one outlet on the lan side, direct routing can be done, because you don't need to consider the operator's part.
When do I need to set up backhaul routing?
Generally speaking, at least two or more three-layer network nodes (that is, communication on different network segments and expanded network segments) are considering the issue of backhaul routing. (Refer to the picture below for an example to make it easier to understand)
When the original route is area A -> area B, A sends an access request to B, with A as the source and B as the destination. At this time, B needs to configure a static route with A as the destination address and B as the source as a referrer route.
The meaning of configuring the referrer route, as I understand it, is that data needs to be bidirectional, sending requests & responses. Static routing is one-way: Static routing is one-way, that is, it only provides data routing along the next hop and does not provide reverse routing. So if you want bidirectional communication between the source node and the destination node or network, you must also configure a backhaul static route. It is often found that a static route to a certain node is configured, but the ping still fails. One of the important reasons is that the return static route is not configured.
Regarding the significance of setting up referrer routes, I have seen several explanations on the Internet:
1. It is to ensure that the internal network port address of the router can access other addresses of the layer 3 switch (after setting the vlan, they are not in the same network segment)
2. In fact, there is no such thing as "referral routing". Don't stick to this term. What I really mean is: Routing is bidirectional. When there is only one-way routing, the network is unreachable. Usually we It can be vividly compared to "data comes in one direction, but because there is no route back, the returned data cannot arrive."