Document page
Computer Science IGCSEPDF 11
142 pagesrevision 46930
PDF 11
Page image rendered from the stored file at 110 dpi; it sharpens as you zoom. Outlines are placed from each region’s stored position on the page (612 × 792 pt).
readable
Source of this text: embedded text layer. The better of the embedded text and OCR is kept.
●
● Hopping (packet passed node to node) prevents loss.
2. Packet Switching
● Definition: Method of transmission where data is divided into packets →
each packet is transmitted independently via different routes →
reassembled at destination.
● Routers: Devices at each node examine header information → choose next
path.
If the shortest route is busy, alternative free routes are chosen.
Advantages
1. No need for a single dedicated communication line.
2. Failed/busy routes can be avoided (fault tolerance).
3. Very scalable → easy to expand network usage.
4. High speeds possible, especially across global networks.
Disadvantages
1. Some packets may be lost in transmission.
2. Real-time streaming suffers (errors, jitter, lag).
3. Delays occur when packets are reassembled.
3. Transmission Modes