| Configuring for compression is
simple: from the interface, issue the compress predictor, compress
stac, compress mppc, or ip tcp header-compression
command on both sides
of the link.
Compression Algorithm
Predictor is more memory intensive and less CPU
intensive, whereas Stacker and MPPC are more CPU intensive and less
memory intensive. Memory intensive means that an extra memory
allowance is required.
You need to consider this memory usage when
implementing compression on any specific router. If you use a Cisco
2500 series router or better, it should be acceptable to use either
of these methods if you have sufficient memory in the router.
Use caution with smaller systems that have less memory and slower
CPUs, and ensure that you are not overloading the router. The interface
command to enable compression follows:
Router(config-if)#compress
[predictor|stac|mppc]
TCP Header Compression
The TCP header compression technique is fully
described in RFC 1144. It is supported on serial lines by using HDLC,
PPP, or SLIP encapsulation. You must enable the compression on both
ends of the connections for TCP header compression to work. Only TCP
headers are compressed-UDP headers are not affected. The following
is the interface command used to activate TCP header compression:
Router(config-if)#ip tcp
header-compression
The ip tcp header-compression passive
command specifies that TCP header compression is not required,
if the router receives compressed headers from a destination, then
use header compression for that destination.
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Lab
Activity |
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The
Atlanta Bread Company is again reviewing the
costs incurred by the Macon office for dialin
access to the core router. The CTO has
recommended that Stacker compression be added
to the asynchronous link between Atlanta and
Macon to maintain compatibility with the Cisco
700 series. You will configure compression
between the Atlanta core router and the Macon
remote office. |
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