📋 LAB Configuration Guideline

1. How to configure:
- Select mode: UM (unacknowledged) or AM (acknowledged).
- Set loss probability – determines how often a PDU is lost (NACK in AM, out‑of‑order in UM).
- For AM, set retransmission delay (RTT in slots).
- Use Send Next PDU to transmit the next sequence number.
- Use Advance Slot to move time forward (for retransmission timers).

2. What will be the flow:
- UM: PDUs are transmitted with increasing SN; if a PDU is lost (or delayed), the receiver may see a gap. Once consecutive PDUs arrive, they are delivered to upper layer.
- AM: Same, but lost PDUs trigger NACK and retransmission. Retransmissions have same SN and are sent after RTT.

3. What student can expect:
- Transmitter buffer shows SN of PDUs in flight.
- Receiver buffer shows received PDUs; gaps are visible.
- Delivered PDUs appear in order below.
- In AM, retransmissions are shown in a separate queue.

4. Recommended exploration:
- Start with UM, loss 0, send several PDUs – observe immediate delivery.
- Increase loss, send PDUs – see gaps and reordering.
- Switch to AM, set RTT, and see how NACKs trigger retransmissions.