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Wireless: LTE Data Throughput, which MTU Size should device choose as Verizon requirement? What's the relationship between MTU and packet size?

Environment/Versions

8100 LTE, Verizon Data Throughput tests

 

Answer

As defined in Verizon LTE 3GPP BAND 13 NETWORK ACCESS document, device shall set the MTU size to 1428 bytes for all PDN connections.

There's MTU Size parameter in UE file Spirent Data Client Tab, thus we should configure this to 1428 as required by Verizon.

Script defines test parameter UDP Packet Size (under 7- Advanced Options) for all UDP throughput tests.

It sets  IPv4 UDP Packet Size to 1400 and IPv6 UDP Packet Size to 1380. The reason being:

MTU = payload(packet size) + header
 
IPv4 header is 20, IPv6 header is 40, UDP header is 8. So we set IPv4 UDP packet size to 1400 (1428-20-8), IPv6 UDP packet size to 1380 (1428-40-8).

Sometimes we see below warning displayed on TestManager, e.g. below is warning from IPv4 UDP tests:

It means test parameter IPv4 UDP Packet Size is 1400, while MTU Size in UE file is 1432, so packet size calculated based on MTU is 1404 (1432-20-8).

To reslove this warning, just set UE file MTU size to 1428.

 


Product : Data throughput,Wireless,LTE,LTE Test System