Trouble shooting
“Ping: Request timed out” in DTDMA Radio Networks
This is specific to scenarios which used DEMAND BASED slot allocation in the MAC layer and having multiple emulation applications. When multiple systems trying to ping, the slot allocation methodology, causes delays that exceed the TTL of ping packet. A simple way to overcome this problem is to set the slot allocation technique as ROUNDROBIN.
It may happen that even after setting ROUNDROBIN as the slot allocation technique, a user could see the “Ping: Request timed out” error. This is due to high-rate traffic flows of non-emulation applications flowing through the emulator system. For example, consider a scenario with 4 systems A, B, C and D, such that
A is the source system. The system sending Ping Request.
B is the emulation server where NetSim is run.
C is the destination System. The system sending Ping Reply.
D is another system that is not a part of the Emulation set up under study
In this example, A pings C with traffic flowing through B. If simultaneously there is other traffic flowing from A to D (applications that are not part of Emulation set-up under study), then this traffic would also flow via emulator system due to static route setting. This will cause delays and the ping packets may then exceed the TTL. To avoid this set static route to a particular Host system instead of adding static route based on Network. In this same example, say the systems A, B, C and D are in the network 192.168.0.0/24, with IP addresses 192.168.0.2, 192.168.0.3, 192.168.0.4 and 192.168.0.5 respectively. Then user should not set
route add 192.168.0.0 MASK 255.255.255.0 192.168.0.3 METRIC 1
but instead, add the host specific static route
route add 192.168.0.4 MASK 255.255.255.255 192.168.0.3 METRIC 1
Latest FAQs
Up to date FAQs on NetSim’s Emulation library is available at https://tetcos.freshdesk.com/support/solutions/folders/14000115083