L2 Payload Compression

L2 payload compression reduces the size of the frame payload. Entire IP packet is compressed.

Software compression can add delay due to its complexity. Hardware compression reduces the compression delay. Serialization delay is reduced; overall latency might be reduced.

L2 payload compression reduces the size of the frame payload. Entire IP packet is compressed.

Software compression can add delay due to its complexity. Hardware compression reduces the compression delay. Serialization delay is reduced; overall latency might be reduced.

The figure shows a basic block diagram of a Layer 2 payload compression method. When a router forwards a packet, the packet is subjected to the Layer 2 compression method after it has been encapsulated at the output. The compression method squeezes the payload of the Layer 2 frame (the entire Layer 3 packet), and transmits the packet on the interface.

Layer 2 payload compression is a CPU-intensive task and can add per-packet compression delay due to the application of the compression method to each frame. The serialization delay, however, is reduced, because the resulting frame is smaller. Serialization delay is the fixed delay that is required to clock the frame onto the network interface. Depending on the complexity of the Layer 2 payload compression algorithm, overall latency might be reduced, especially on low-speed links.

Cisco routers support hardware-assisted compression to reduce the CPU load and the Layer 2 payload compression delay.

Example: L2 Payload Compression Results

The figure compares three throughput and latency scenarios on a PPP link.

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