Data Compression For Wan Links - HP 200 Series Services And Applications

Data Compression for WAN Links

Using data compression on wide area links has ramifications that must be
considered when implementing routed network solutions. This note will do
the following:
Describe current methods of data compression.
Briefly explain HP's compression algorithm.
Describe the performance test method used for testing compression
with HP routers.
Report compression test results.
Give some general guidelines for effectively designing networks that
utilize compression.
What is Compression?
Compression is a method of encoding data such that the resulting file or
packet is smaller than the original. Therefore, when the data is sent, say
over a wide area link, it will utilize less bandwidth than the original data
uses. At the other end of the link, the data is then uncompressed to its
original size. In this way, one can gain improved WAN throughput without
having to upgrade to higher speed lines. For example, using the HP
AdvanceStack Router 650, running compression on 64 Kbit/s links can yield
throughputs of up to 96 Kbit/s. See the "Design Guidelines" section for more
details.
Data compression is achieved by replacing repeating strings of data with a
smaller string called a "key". Compression algorithms use what is called a
"dictionary", which contains the mappings of strings to their respective keys.
The sending device removes the repeating strings within each packet and
replaces them with the key string, and the receiving device reverses the
process, restoring the original data and removing the key. Both the sending
Data Compression for WAN Links
What is Compression?
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