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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:
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Link compression (also known as per-interface compression)
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Payload compression (also known as per-virtual-circuit compression)
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TCP header compression
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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.
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