Meaning and mechanism
Packets are units that divide data and control information for transmission. Even if a portion of the entire message arrives first, recovery is not completed if the necessary remaining parts are not present.
If packets are lost during transmission, it is possible to resend them using acknowledgment responses or time limits. Resending does help with transmission, but it requires additional time and resources.
Relationships and conditions
The number of packets at a fixed payload size is calculated as ceil(message bytes / payload bytes). The actual transmitted amount includes headers and retransmission data as well.
The experiment utilizes independent paths, simple loss, and a limited number of retries. It does not accurately simulate actual protocols’ congestion control, sequence ordering, and bandwidth sharing.
What to observe in the simulation
Retransmission can complete a message but adds delay.
This simplifies real protocols: independent parallel routes, up to 40 retries, no headers or bandwidth contention.
Key relationships and symbols
packets = ceil(bytes / payload)
| Symbol | Meaning | Unit |
|---|---|---|
| payload | Payload size carried by a packet | byte |
| Delay | From the start of transmission to the arrival of the necessary results, the time. | Time |
Worked example
What restores out-of-order packets?
Sequence numbers · Retransmission can complete a message but adds delay.
Common misconceptions
- It is not the case that if a packet is lost in one communication method, messages cannot be permanently restored in that method forever.