Packets and links
Queues, and who pays for them
What happens when packets arrive faster than a link can send them.
A link that is busy does not refuse the next packet; it queues it. Queueing delay is the only kind of delay in this whole model that depends on what else is going on, which is why it is the one that arrives without warning and leaves without explanation.
The queue has a finite depth, and when it is full the next packet is dropped. That is tail drop, and it is a completely different failure from a lossy link even though both show up as a missing packet: the packets before it are still in flight and still arriving.
Predict
Packets are being lost only when the service is busy, and never when it is quiet. What does that point at?
Comes after Latency and bandwidth are not the same number.