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Wireless LTE/CDMA products: How to debug Ping failure issue?


Suppose we initiate Upload Ping from Client PC to Application Server.



Below is how ping request goes to Application Server:
1. Prior to Ping, script adds a route on Client PC, which ensures Ping request to will go through air interface.
2. Client PC sends a ping request, identified with destination IP
3. UE forwards ping request to landslide ( via air interface.
4. Landslide forwards it to switch (, and switch finds192.168.0.125/70 is within its subnet, thus forwards the request to Application Server.

Below is how ping response goes to laptop:
1. Application Server sends ping response, identified with UE IP 192.168.7.x (CDMA) or 192.168.9.x (LTE).
2. Ping response goes to switch ( Switch is responsible for data packets within same subnet(192.168.0.x subnet), here switch figures out IP 192.168.7/9.x is not in the same subnet, thus switch will forward the data packets to the router.
3. Router checks its internal IP route table, found “ip route 192.168.7/9.0”. This means ping response to 192.168.7/9.x will go through (landslide IP). Thus router forwards the ping response to landslide.
4. Landslide forwards the ping response to 192.168.7/9.x (UE) through air interface, thus laptop gets ping response.

We can capture Wireshark logs on each node, and then investigate which node lost packets following the logic above.