10.3
Optimizing Traffic Flow with Data Compression
10.3.1 Compression overview

Many strategies and techniques exist for optimizing traffic over WAN links, including queuing and access lists. One of the more effective methods, however, is compression. This section discusses how to optimize the WAN traffic over the WAN link by compressing data on the WAN link.

Data-compression technology maximizes bandwidth and increases WAN link throughput by reducing frame size and thereby allowing more data to be transmitted over a link.

The Figure graphically displays the following various types of data compression that Cisco equipment supports:

  • Link compression (also known as per-interface compression)

  • Payload compression (also known as per-virtual-circuit compression)

  • TCP header compression

  • Microsoft Point-to-Point Compression (MPPC)

The default method of transmitting data across a serial link is the uncompressed format. This allows headers to be used in the normal switching operation but can consume more bandwidth than desired.

Cisco 3600 series routers

Cisco 3600 series routers now support a compression port module that provides high-performance, hardware-based data compression using simultaneous Stacker compression algorithms. Independent, full-duplex compression and decompression capabilities are used on PPP encapsulated packets.

The data-compression advanced integration module (AIM) provides hardware-based compression and decompression of packet data transmitted and received on the serial network interfaces of the Cisco 2600 series router without occupying the port module slot, which might otherwise be used for additional customer network ports. Supported are the industry-standard Limpel Zif Stac (LZS) and MPPC algorithms over PPP or Frame Relay. High-Level Data Link Control (HDLC) is not supported. The data compression AIM requires Cisco IOS Release 12.0(1)T or later.

The data-compression AIM provides a hardware-based compression that yields a higher level of performance than that available from the main chassis CPU running the Cisco IOS compression feature. The data-compression AIM series cards provide enhanced versatility, network peripheral integration, and performance for Cisco 2600 series routers. The data-compression AIM delivers higher levels of WAN bandwidth optimization by supporting compression ratios of up to 4:1 with 8-Mbps throughput.