Services Are Interrupted After IPSG Is Enabled on the Upstream Interface

Procedure

1. Check whether IPSG has been enabled on an upstream interface.

   Generally, IPSG is enabled on the user-side (downstream) interface. If IPSG is also enabled on the upstream interface, the return packets may be discarded. As a result, user services are interrupted.

   In Figure 1, after static binding entries are configured on the switch for Host_1 and Host_2, and IPSG is enabled on IF1, IF2, and IF3, the hosts cannot access the Internet. However, the hosts can communicate with each other. Host_1 is used as an example here to describe the fault symptom:

   • Host_1 sends a packet to the Internet. When the packet reaches IF1 of the switch, the switch detects that the packet matches a binding entry, and forwards it.
   • A packet is sent from the Internet to Host_1. When the packet reaches IF3, the switch detects that the packet does not match any binding entry, and discards the packet.
   Figure 1 Services are interrupted after IPSG is enabled on the upstream interface
   
   

2. Perform the following operations:
   1. Run the display ip source check user-bind interface interface-type interface-number command to check whether IPSG is enabled on the upstream interface IF3.
   2. If "ipv4 source check user-bind enable" or "ipv6 source check user-bind enable" is displayed, IPSG has been enabled on the upstream interface. Run the undo ip source check user-bind enable command in the interface view to disable IPSG on the upstream interface IF3.