Datagram Networks
Overview/Summary:
Datagram networks are a type of packet-switched network where each packet, known as a datagram, is treated independently. Each datagram contains the destination address and is routed individually through the network. This means that packets belonging to the same message may take different paths and arrive out of order. Datagram networks are characterized by their flexibility and efficiency, but they require more complex routing and may experience higher latency variations.
Detailed Explanation:
In a datagram network, no connection is established between the sender and receiver before data transmission. Instead, each datagram carries the full destination address and is forwarded by routers based on their current routing tables. Routers make decisions on a per-packet basis, meaning that different packets of the same message can take different routes. This approach offers several advantages:
- Flexibility: Datagram networks can adapt quickly to network congestion or failures. If a particular route is congested, packets can be routed through alternative paths.
- Efficiency: Resources are only used when data is actually being transmitted. There’s no overhead of establishing and maintaining a dedicated connection.
- Robustness: If a router fails, only the packets passing through that router are affected. Other packets can continue to be transmitted through different routes.
However, datagram networks also have some drawbacks:
- Out-of-Order Delivery: Packets may arrive at the destination in a different order than they were sent. The receiving host must reassemble the message.
- Higher Latency Variation: The varying routes can lead to different delays for different packets, resulting in higher latency variation.
- More Complex Routing: Routers need to maintain up-to-date routing tables to make forwarding decisions for each packet.
- No Guaranteed Delivery: There’s no guarantee that all packets will reach the destination. Packet loss can occur due to congestion or network failures.