Size GTP-U transport for a bearer population, including encapsulation overhead and packet-per-second load.
GTP-U wraps every user packet in an 8-byte GTP header, an 8-byte UDP header and a 20-byte outer IP header. Because that cost is per packet, the percentage overhead depends entirely on the average packet size — small-packet traffic such as signalling or gaming pays far more than bulk video. S1-U and N3 backhaul is dimensioned in Gbps but policed in packets per second, and forgetting 36 bytes of encapsulation is a reliable way to saturate a link at 96% of its nominal capacity.
GTP Tunnel
transport = user payload × (1 + header bytes ÷ average packet size); packet rate = payload bits ÷ (packet size × 8).
transport = user payload × (1 + header bytes ÷ average packet size); packet rate = payload bits ÷ (packet size × 8). GTP-U wraps every user packet in an 8-byte GTP header, an 8-byte UDP header and a 20-byte outer IP header. Because that cost is per packet, the percentage overhead depends entirely on the average packet size — small-packet traffic such as signalling or gaming pays far more than bulk video.
S1-U and N3 backhaul is dimensioned in Gbps but policed in packets per second, and forgetting 36 bytes of encapsulation is a reliable way to saturate a link at 96% of its nominal capacity.
This calculator takes 4 inputs: Active bearers, Average throughput per bearer, Average user packet size, GTP-U + UDP + IP header. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.