
Configuring PPP Services
2-20 114068 Rev. A
Data compression eliminates redundancies in data streams. When you use
compression on your network, bandwidth efficiency improves, and you can
transmit more data over a given amount of network bandwidth.
Bay Networks data compression services for PPP include
• Software-based compression for all platforms and all serial interfaces
• Hardware-based data compression for PPP networks that use the octal
synchronous link module for the Backbone Node (BN
®
), using only FRE
®
-2
processors. Bay Networks provides hardware compression as an optional
daughterboard that attaches to the octal synchronous link module.
• Hardware-based data compression for PPP networks that use the octal
synchronous link module for the Access Stack Node (ASN
™
), using any link
module. Bay Networks provides hardware compression as an optional
daughterboard.
You can use data compression on all PPP circuits, including multiline, multilink,
bandwidth-on-demand, dial-on-demand, and dial backup lines. You can use
compression separately on each member of a multilink bundle. When you use
compression on a bandwidth-on-demand, dial-on-demand, or dial backup circuit,
the data compression feature automatically configures or deletes compression as
lines are added to or removed from the circuit.
For complete descriptions of hardware and software data compression,
descriptions of compression parameters, and instructions for configuring
compression over a PPP interface, see Configuring Data Compression Services.
Synchronous versus Asynchronous Connections
When you configure a dial (switched) circuit, you can specify whether you want
transmission on that circuit to be synchronous or asynchronous. Switched services
include dial-on-demand, bandwidth-on-demand, and dial backup. These function
independently of the physical modem communication method.
In synchronous transmissions, the timing of each data transfer has a specific time
relationship to the previous and next data transfer. Synchronous data transfers are
fast because of the low network overhead relative to the amount of data
transferred in each block, but they require more expensive, clock-driven data
transmission equipment. In general, you might use synchronous data transmission
for large data transfers.
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