The upper layer route cannot Ping the lower layer route

introduction ：
Recently, a project needs to deploy the data upload module and data management module to two servers under different network segments for simulated transmission test . Find out 192.168.1 The server of the network segment cannot ping through 192.168.0 Server of network segment , But the reverse can be , That's one-way ping through . I have tried to close the firewall or open ports , no way .
Ask the colleagues of network implementation to know , Our company's network is divided into two layers ,192.168.1 It's the upper class ,192.168.0 It's the lower level . The lower layer route can ping Connect upper layer route , Not vice versa . But if the switch is a non fool switch, it can be set , Let the upper layer route ping Through the lower layer route .

Refer to other network materials ：
In multilayer network architecture , The network connection is , Layer 1 routing Lan The interface is connected to the lower layer route Wan mouth , There is a server connected to it under the second layer route Lan On the mouth , By setting port mapping on the second layer router, the LAN server is mapped to the first layer , That is, you can access the servers in the layer 2 routing in the LAN of the layer 1 routing . But there is a strange problem , The LAN with layer 1 routing cannot ping Layer 2 router Wan Address , Later, after online search, it was found that it was due to the router Wan By default, it is forbidden Ping Of , If you want it to be able to ping Need to be in the router 【 Wireless settings 】-——【 Security Settings 】 Remove the checked “ Ignore from WAN mouth Ping“, If once checked , After enabling this function, the router will no longer respond from WAN Oral Ping testing , That's what we just said , You can't ping through wan mouth