Payload Compression; Aldc Vs. Lzs Compression Comparison Table; Table D-1. Aldc Vs. Lzs Compression Comparison - Comtech EF Data CDM-570A Installation And Operation Manual

•
Header Compression Statistics will display the total bytes of the pre-compressed and
post-compressed traffic and effective compression ratio.
D.1.2.7.2.2 Payload Compression
The Packet Processor features industry-leading payload compression for IP traffic. Implemented
in the hardware for maximum throughput and efficiency, payload compression can reduce the
required satellite bandwidth by as much as 40–50%. Traffic optimization through Payload
Compression is an optional feature of the Packet Processor. Note the following:
•
Available as a FAST feature
•
Uses AHA chip
•
Compression algorithm applied to all data (HDLC header excluded)
•
Compression statistics are fed back to QoS in order to maximize WAN utilization while
maintaining priority, jitter and latency
•
1024 simultaneous compression sessions to maximize compression across multiple
distinct traffic flows
•
Compression algorithm not applied to RTP streams because this traffic is already
compressed and would only INCREASE the sat bandwidth if compressed again
•
Additional statistics have been added to the compression statistics menu in order to
provide feedback on the compression efficiency that has been achieved
•
Payload Compression is selectable on a per route basis
D.1.2.7.2.3 ALDC vs. LZS Compression Comparison Table
The numbers in Table D-1 were compiled using a test program created in-house
by Comtech EF Data. This program takes the target benchmark files and splits
the files into payload-sized chunks, then compresses each chunk in a separate
invocation of the compression algorithm. This is important to note because
most compression algorithms are applied to the entire file data set as a single
invocation of the compression algorithm, which is easier for other types of
compression algorithms (LZS, GZip specifically). This, of course, does not apply
to streamed packet data across an IP network (e.g., FTP transfer).
Payload
Algorithm
1472
1000
ALDC
1472
1000
Optional High Performance Packet Processor
CDM-570L/570AL Satellite Modem with Optional Packet Processor

Table D-1. ALDC vs. LZS Compression Comparison

File Set Ratio
size
Calgary
500
100
Canterbury
500
100
Algorithm
1.76
1.76
1.77
2.09
LZS
1.71
1.72
1.74
2.04
D–17
Payload
File Set Ratio
size
1472 1.66
1000 1.66
Calgary
500 1.68
100 1.97
1472 1.61
1000 1.62
Canterbury
500 1.63
100 1.91
MN-CDM570A
Revision 5