Bandwidth limitations

On the presumption that your test LTM is a VE instance, article K15831 states:

When calculating throughput, the BIG-IP VE system accounts for packets ingressing and egressing the system separately. However, both ingress and egress throughput values are used when enforcing the licensed throughput rate.

Ingress packets reach a buffer that is polled periodically for queued bytes. When the queued number of bytes reaches the limit, as determined by a sliding mechanism, the rate shaper begins limiting ingress traffic. Throughput for egress traffic is determined by the amount of bytes sent over predefined sliding time windows. If the number of bytes sent surpasses the limit for a given time window, the rate shaper starts limiting the egress traffic.

The rate shaper throttles throughput to the licensed rate at the packet level, rather than at the connection level. Ingress and egress packets are dropped during the limiting process and no management is done at the connection level.

Does that help?