fix broken link in load_balance.md

en_us/frontend_principle/load_balance/load_balance.md

@@ -39,7 +39,7 @@ The above two schemes are compared in the following table.
 
 The advantage of **the naming service+client strategy method** is that the client accesses the service directly without additional resource consumption. However, the actual effect of this method strongly depends on the cooperation of the client. To implement more complex strategies on the client, the client SDK is usually introduced, which introduces the cost of client upgrading. For many companies, there are many kinds of client software, belonging to different teams, and it is difficult to upgrade in time. In addition, the execution granularity of this method is relatively coarse. The interaction between the client and the naming service cannot be too frequent. The interaction frequency of several seconds is already very high, but even in this way, it is impossible to control the granularity of a single connection/request.
 
-In some scenarios, the load balancer cannot be used, the naming service+client strategy is the only solution. For example, in [Internet Scheduling Scenario](../../design/gslb/gslb. md), you can only use DNS.
+In some scenarios, the load balancer cannot be used, the naming service+client strategy is the only solution. For example, in [Internet Scheduling Scenario](../../design/gslb/gslb.md), you can only use DNS.
 
 | Solution                         | Control on Traffic                                           | Resource Consumption                                         | Requirements for Clients                                     | Applicable Scenarios                                         |
 | -------------------------------- | ------------------------------------------------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ | ------------------------------------------------------------ |
@@ -66,7 +66,7 @@ Some software supports both layer-4 load balancing and layer-7 load balancing, s
 
 + Layer-4 load balancing software: It requires high processing power to achieve high cost performance ratio and is used to resist DDoS attacks from the external network.
 
-  The BGW software introduced in "[Introduction to Network Front End](../introduction/introduction. md)" uses C language and is developed based on DPDK technology. It can handle 50Gbps of network traffic on a single x86 server, and can handle more than 1 million new connections per second. To achieve higher performance, the overall logic of the software needs to be simple, without the function of high resource consumption. At the same time, because of the high requirements for performance and stability, the cost of developing new features is relatively high, and the cycle of developing new features and going online is relatively long.
+  The BGW software introduced in "[Introduction to Network Front End](../introduction/introduction.md)" uses C language and is developed based on DPDK technology. It can handle 50Gbps of network traffic on a single x86 server, and can handle more than 1 million new connections per second. To achieve higher performance, the overall logic of the software needs to be simple, without the function of high resource consumption. At the same time, because of the high requirements for performance and stability, the cost of developing new features is relatively high, and the cycle of developing new features and going online is relatively long.
 
 + Layer-7 load balancing software: Its functions are relatively complex, and new features need to be added continuously.
 
@@ -99,4 +99,4 @@ The following figure illustrates the mixed use of the layer-4 load balancing sof
 
 ## links
 Previous: [Chap3 Trend of Network Front End Technology](../../../en_us/frontend_principle/trend/trend.md)  
-Next: [Chap5 Design Considerations of BFE](../../../en_us/design/ideas/ideas.md)
+Next: [Chap5 Design Considerations of BFE](../../../en_us/design/ideas/ideas.md)